Sensor chip for measuring glucose and temperature of a blood sample

TECHNICAL FIELD

0001The present invention relates to a biosensor system for measuring temperature and glucose for a blood sample and the use of a sensor chip for measuring temperature and glucose for a blood sample.

BACKGROUND ART

0002A portable biosensor system provided with a measuring device having a calculating unit and a sensor chip detachable from the measuring device is used for measuring an analyte concentration, for example a blood glucose concentration (blood glucose value) in a blood sample is known in the prior art. The analyte concentration is calculated by an optical method or an electrochemical method based on an amount of a reductant or an oxidant produced by an oxygen cycling reaction mediated by an oxidoreductase that uses the analyte as a substrate. The speed of the oxygen cycling reaction depends on the temperature that promotes the reaction (reaction temperature). As a result, the concentration of the analyte is preferably corrected with reference to the reaction temperature.

0003The reaction temperature for example is measured by a temperature sensor disposed in the measuring device (Patent Literature 1). However, in the biosensor system according to Patent Literature 1, the inner portion temperature of the measuring device is measured, and therefore the measured reaction temperature does not accurately reflect the temperature of the blood sample. As a result, an error may result in the measurement of the analyte concentration.

0004Patent Literature 2 - 4 disclose a biosensor system for improving the measurement accuracy of the reaction temperature. The biosensor system in Patent Literature 2 and 3 includes a heat conduction member in proximity to the blood sample retention unit of the sensor chip, and detects the temperature of the blood sample transmitted through the heat conduction member with a temperature sensor disposed in the measuring device. Since the biosensor system in Patent Literature 2 and 3 includes a resin plate disposed between the heat conduction member and the blood sample retention unit, the heat conduction member does not come into contact with the blood sample. The biosensor system in Patent Literature 4 includes a temperature sensor and a heat conduction member disposed in a mounting unit of the measuring device for mounting of the sensor chip, and therefore transmits the temperature of the blood sample to the temperature sensor through the heat conduction member. Further, <patcit id="pcit0001" dnum="WO2005012900A"><text>WO2005/012900</text></patcit> discloses a biosensor having multiple electrical functionalities located both within and outside of the measurement zone in which a fluid sample is interrogated. Incredibly small and complex electrical patterns with high quality edges provide electrical functionalities in the biosensor and also pro-vide the electrical wiring for the various other electrical devices provided in the biosensor. In addition to a measurement zone with multiple and various electrical functionalities, biosensors as disclosed in this document may be provided with a user interface zone, a digital device zone and/or a power generation zone. The biosensors offer improved ease of use and performance, and decrease the computational burden and associated cost of the instruments that read the biosensors by adding accurate yet cost-effective functionalities to the biosensors themselves.

CITATION LIST

PATENT LITERATURE

0005<ul id="ul0001" list-style="none"><li>Patent Literature 1: <patcit id="pcit0002" dnum="JP2003156469A"><text>Japanese Patent Application Laid-Open No. 2003-156469</text></patcit></li><li>Patent Literature 2: <patcit id="pcit0003" dnum="JP2001235444A"><text>Japanese Patent Application Laid-Open No. 2001-235444</text></patcit></li><li>Patent Literature 3: <patcit id="pcit0004" dnum="JP2003042995A"><text>Japanese Patent Application Laid-Open No. 2003-42995</text></patcit></li><li>Patent Literature 4: Pamphlet of <patcit id="pcit0005" dnum="WO2003062812A"><text>PCT International Application No. 2003/062812</text></patcit></li></ul>

SUMMARY

TECHNICAL PROBLEM

0006When a user with a biosensor system moves into a location that has a large temperature difference (for example, moves from an external location in summer or winter into a building), the measuring device will be incapable of tracking the sharp variation in the environmental temperature, and for a certain period of time, will maintain a higher temperature or lower temperature than the environment of the current location. For example, when moving the measuring device from a 40°C or a 10°C environment to a 25°C environment, a period of approximately 30 minutes may be required until the temperature of the measuring device reaches 25°C (Patent Literature 1).

0007It is difficult to completely eliminate the effect of the temperature of the measuring device when measuring the reaction temperature by a temperature sensor in a measuring device. Thus when there is a sharp change in the temperature of the environment in which the sensor is used, an error will tend to be produced in the measurement of an analyte concentration when using the biosensor system disclosed in Patent Literature 2 -4.

0008Since the temperature of the blood sample in the biosensor system disclosed in Patent Literature 2 - 4 is communicated by heat transfer through the resin plate and the heat conduction member to the temperature sensor, the measured reaction temperature does not accurately reflect the temperature of the blood sample.

0009The present invention has the object of providing a biosensor system that measures a temperature of a blood sample and suppresses the production of a measurement error resulting from the temperature of a use environment.

SOLUTION TO PROBLEM

0010This object is achieved by means of a biosensor system comprising a sensor chip comprising: a glucose measurement system configured to measure glucose of a blood sample, a temperature measurement system configured to measure temperature of the blood sample, and a capillary in which the blood sample is introduced, the capillary introducing the blood sample into the temperature measurement system and the glucose measurement system in this order, wherein the capillary is formed by an insulating plate, a spacer and a cover; wherein the cover is disposed on the spacer, which is disposed on the insulating plate; wherein a notch in the spacer functions as the capillary, which communicates with the an introduction port that opens onto an outer portion of the sensor chip and a discharge port included in the cover in proximity to the opposite end to the introduction port: wherein the glucose measurement system includes a first working electrode, a first counter electrode and a reagent portion; wherein the first working and the first counter electrodes have portions disposed on the insulating plate to face the capillary and the reagent portion is formed on the insulating plate to cover the whole of the portion facing the capillary of the first working electrode and to partially cover the portion facing the capillary of the first counter electrode; wherein the reagent portion includes an oxidoreductase and an electron mediator; wherein the temperature measurement system includes a second working electrode and a second counter electrode; wherein the biosensor system further comprises a measuring device including a control circuit configured to apply a voltage to the second working and counter electrodes of the sensor chip for measuring the temperature of the blood sample.

0011In an embodiment of the invention, a predetermined direct current voltage is applied in this sensor chip to the temperature electrodes so that the effect of hematocrit is low during measurement of the biological sample temperature by the temperature electrodes.

0012In this manner, temperature measurement of a biological sample is enabled without reference to a hematocrit value in the biological sample. As a result, the temperature measurement accuracy for a biological sample can be improved, and the accuracy in relation to various types of corrections using the temperature of the biological sample can also be improved.

0013According to the first embodiment, the uptake amount of the biological sample into the capillary is 5µL or less, and the application time of the direct current voltage to the temperature electrodes is 15 seconds or less.

0014According to the first or the second aspect, and the predetermined direct current voltage is within a range in which the solvent of the biological sample is subjected to electrolysis.

0015According to any one of the first to the third aspect, the sensor chip is disposable.

0016A biosensor system according to the invention is a biosensor system for measuring the concentration of glucose in a blood sample, and includes temperature electrodes disposed to make contact with the blood sample, and having at least a working electrode and an counter electrode for measuring the temperature of the blood sample, and a concentration measuring unit configured to measure a concentration of glucose in the blood sample.

0017In this manner, direct measurement of the temperature of a blood sample is enabled in contrast to a conventional sensor chip provided with temperature electrodes that measure the heat transmitted through a resin plate, heat conduction member, or the like. As a result, the production of a measurement error caused by the temperature of the use environment can be suppressed, and an improvement in the measurement accuracy of the analyte concentration in a blood sample is enabled.

0018In a biosensor system according to the invention, the concentration measuring unit is formed from analysis electrodes including at least a working electrode and an counter electrode.

0019For a sensor chip according to an embodiment the temperature electrodes and the analysis electrodes are provided separately.

0020In this manner, accurate measurement of a concentration of an analyte in a blood sample is enabled.

0021A biosensor system according to the invention further includes a sample introduction port and a capillary configured to introduce a blood sample from the sample introduction port to the temperature electrodes and the analysis electrodes. The temperature electrodes are disposed at a position closer to the sample introduction port than the analysis electrodes.

0022For a sensor chip of an embodiment, and the temperature electrodes are disposed to not make contact with at least one of the oxidoreductase or the electron mediator.

0023In this manner, the temperature of the blood sample can be accurately measured.

0024For a sensor chip of an embodiment, the concentration measuring unit further includes a reaction reagent that induces an oxidation·reduction reaction, and the temperature electrodes are disposed to not make contact with the reaction reagent that induces the oxidation ·reduction reaction.

0025<b>In</b> this manner, contact of the reaction reagent with the temperature electrodes can be avoided, and accurate measurement of the blood sample temperature is enabled.

0026A sensor chip useful for understanding the invention is disposed to not make contact with any reagent.

0027In this manner, contact of any reagent with the temperature electrodes can be avoided, and accurate measurement of the blood sample temperature is enabled.

0028For a sensor chip of an embodiment, the working electrode of the temperature electrodes is common to at least either the working electrode or the counter electrode of the analysis electrodes.

0029For a sensor chip of an embodiment, the counter electrode of the temperature electrodes is common to at least either the working electrode or the counter electrode of the analysis electrodes.

0030(0029] For a sensor chip of an embodiment, the concentration measuring unit includes at least one electrode in addition to the working electrode and the counter electrode, and at least one of the electrodes of the concentration measuring unit other than the working electrode and the counter electrode is common to at least one of the working electrode and the counter electrode of the temperature electrodes.

0031The electrodes included in the concentration measuring unit according to embodiments may be combined with at least one of the working electrode and the counter electrode of the temperature electrodes. The sensor chip according to embodiments may include a plurality of working electrodes and/or a plurality of counter electrodes as analysis electrodes. At least one of the plurality of working electrodes and/or counter electrodes may be combined with the working electrode and/or counter electrode of the temperature electrodes.

0032An example of an electrode other than a working electrode and counter electrode according to an embodiment includes <ul id="ul0002" list-style="dash"><li>a hematocrit measuring electrode;</li><li>a measuring electrode for an amount or concentration of a reducing substance;</li><li>a detection electrode for detecting the introduction of blood; and</li><li>a measuring electrode other than a electrode for measuring an amount or concentration of a reducing substance, hematocrit, or glucose concentration.</li></ul>

0033For a sensor chip of an embodiment, the surface area of the working electrode in the temperature electrodes is either the same or smaller than the surface area of the counter electrode in the temperature electrodes.

0034For a sensor chip of an embodiment, at least hematocrit is included as a feature in relation to the concentration of the analyte.

0035For a sensor chip of an embodiment, at least a concentration or an amount of a reducing substance is included as a feature in relation to the concentration of the analyte.

0036The following methods are useful for understanding the invention. A method for measuring a temperature of a biological sample measures a temperature of a biological sample by a sensor chip including temperature electrodes formed from a working electrode and an counter electrode, and a capillary. The method includes an introduction step of introducing a biological sample by the capillary to the temperature electrodes, an application step of applying a direct current voltage to the temperature electrodes, and an adjustment step of adjusting the direct current voltage applied in the application step to a first voltage. The first voltage is set so that the effect of hematocrit on the temperature measurement result during application of the first voltage to the temperature electrodes is reduced.

0037This method enables temperature measurement of a biological sample without reference to a hematocrit value in the biological sample. As a result, the accuracy of the temperature measurement of the biological sample can be increased, and the accuracy in relation to various corrections using the temperature of the biological sample can also be increased.

0038For a method for measuring a temperature , a direct current voltage that enables a reduction of the effect of hematocrit on the temperature measurement result is measured and stored in advance, and the adjustment step adjusts to the first voltage based on the stored direct current voltage.

0039For a method for measuring a temperature of a biological, the uptake amount of the biological sample in the introduction step may be 5µL or less, and the application time of the direct current voltage in the application step may be 15 seconds or less.

0040A method for measuring a temperature of a blood sample measures a temperature of a blood sample using a sensor chip including temperature electrodes formed from a working electrode and an counter electrode. The method includes a step of applying a voltage to the temperature electrodes in contact with the blood sample, a step of acquiring data a related to the temperature of the blood sample based on a dimension of a current flowing in the blood sample by application of the voltage, and a step of calculating a temperature t of the blood sample based on the data a.

0041A temperature t of the blood sample is calculated based on data a related to the temperature of the blood sample that can be acquired by application of a voltage to the temperature electrodes in contact with the blood sample.

0042In this manner, since the temperature t of the blood sample can be calculated based on data a related to the temperature of the blood sample that can be accurately acquired, the production of a measurement error caused by the temperature of the use environment can be suppressed.

0043A method for measuring a concentration of an analyte in a blood sample includes a step of acquiring data a related to the temperature of the blood sample based on the dimension of a current flowing in the blood sample by application of a voltage to the pair of electrodes in contact with the blood sample, a step of acquiring data b related to a concentration of the analyte based on the dimension of a current flowing in the blood sample by a reaction mediated by an oxidoreductase that uses the analyte in the blood sample as a substrate, and a step of measuring a concentration that determines the analyte concentration in the blood sample based on the data a and the data b.

0044Herein, the data a is acquired by directly measurement of the temperature of the blood sample without interposing a resin plate or a heat conduction member, and the analyte concentration in the blood sample is determined based on the data a related to the temperature of the blood sample and the data b related to the concentration of the analyte In this manner, the measurement accuracy of the analyte concentration in the blood sample can be improved.

0045For a method for measuring a concentration of an analyte in a blood sample the concentration measurement step may include a step of correcting the data b based on the data a.

0046<b>In</b> this manner the measurement accuracy of the concentration of the analyte in the blood sample can be improved.

0047A method for measuring a concentration of an analyte in a blood sample may include the method for measuring a concentration of an analyte in a blood sample, the concentration measurement step may include a step of calculating a concentration x of an analyte in a blood sample based on the data b, and a step of correcting the concentration x based on the data a.

0048In this manner, the measurement accuracy of the concentration of the analyte in the blood sample can be improved.

0049In a method for measuring a concentration of an analyte in a blood sample, the concentration measurement step includes a step of calculating a temperature t of the analyte in the blood sample based on the data a, and a step of correcting the data b based on the temperature t.

0050In this manner, the measurement accuracy of the concentration of the analyte in the blood sample can be improved.

0051In a method for measuring a concentration of an analyte in a blood sample according to an embodiment, the concentration measurement step includes a step of calculating a temperature t of an analyte in a blood sample based on the data a, a step of calculating a concentration x of the analyte in a blood sample based on the data b, and a step of correcting the concentration x based on the temperature t.

0052In this manner, the measurement accuracy of the concentration of the analyte in the blood sample can be improved.

0053In a method for measuring a concentration of an analyte in a blood sample, the step of acquiring the data a is performed in advance of the step of acquiring the data b.

0054In this manner, the temperature at the time of acquiring the data b can be more accurately reflected.

0055A method for measuring a concentration of an analyte in a blood sample includes that, the concentration measurement step includes a step of acquiring data c related to the temperature of the blood sample based on the dimension of a current flowing in the blood sample by application of a predetermined voltage to the pair of electrodes in contact with the blood sample after acquisition of the data b, and a step of calculating data d related to the temperature of the blood sample based on the data a and the data c, and a step of correcting the data b based on the data d.

0056In this manner, the temperature at the time of acquiring the data b can be more accurately reflected, and the analyte concentration measurement accuracy for the blood sample can be improved.

0057In a method for measuring a concentration of an analyte in a blood sample, the concentration measurement step includes a step of calculating the temperature t of the blood sample based on the data a, a step of calculating the concentration x of the analyte in the blood sample based on the data b, the step of measuring an environmental temperature t1 on a periphery of the blood sample, a step of comparing the difference between the temperature t and the environmental temperature t1 with a temperature threshold Z, and a step of correcting the concentration x based on the temperature t when the relation | t -t1 | ≥Z is satisfied, and correcting the concentration x based on the temperature t1 when the relation | t -t1 | &lt; Z is satisfied.

0058Herein, the concentration x of the analyte in the blood sample is calculated based on the data b, and the temperature t of the blood sample is calculated based on the data a. The environmental temperature t1 in the periphery of the blood sample is measured. Then the difference between the temperature t and the environmental temperature t1 is compared with a temperature threshold Z, and correction is performed as described below.

0059(0058] <ul id="ul0003" list-style="none"><li>When | t - t1 | ≥ Z is satisfied, the concentration x is corrected based on the temperature t</li><li>When | t - t1 | &lt; Z is satisfied, the concentration x is corrected based on the temperature t1</li></ul>

0060<b>In</b> this manner, since the concentration x can be corrected using an appropriate temperature in response to an external temperature environment, a measurement accuracy for the analyte concentration in the blood sample can be improved.

0061A method for measuring a concentration of an analyte in a blood sample includes thatof a temperature is contained in the data a related to the temperature of the blood sample, and a glucose concentration is contained in the data b related to the concentration of the analyte.

0062(0060] Herein, the temperature is included as a feature of the data acquired as data a, and the glucose concentration is included as a feature of the data acquired as the data b.

0063According to a method for measuring a concentration of an analyte in a blood sample, hematocrit is included in the data b related to the concentration of the analyte.

0064Herein, hematocrit is included as a feature of the data acquired as the data b.

0065According to a method for measuring a concentration of an analyte in a blood sample, the concentration or amount of the reducing substance is contained in the data b related to the concentration of the analyte.

0066Herein, the amount or concentration of the reducing substance is included as a feature of the data acquired as the data b.

0067According to a method for measuring a concentration of an analyte in a blood sample, at least two features of the data included in the data a and the data b are measured at the same time.

0068Herein, when the data a and the data b are measured, at least two features of the data are measured at the same time. For example, the concentration or the amount of the reducing substance and the glucose concentration are measured at the same time.

0069<b>In</b> a method for measuring a concentration of an analyte in a blood sample , independent measurement of the respective data included in the data a and the data b is executed.

0070Herein, when the data a and the data b are measured, two or more features are not measured at the same time, but are measured separately. The order of measuring the features may be arbitrary.

0071In a method for measuring a concentration of an analyte in a blood sample , the measurement of the data contained in the data a and the data b is performed in order of temperature, glucose concentration, concentration or amount of the reducing substance, and hematocrit.

0072Herein, the order of measuring the data is specified. In this manner, effective results can be obtained with respect to speed, accuracy, and burden on the electrodes.

0073In a method for measuring a concentration of an analyte in a blood sample, the measurement of the data contained in the data a and the data b is performed through independent electrodes.

0074Herein, when measuring the data contained in the data a and the data b, such measurement is performed by respectively independent electrodes.

0075The biosensor system according to the invention includes a measuring device including a control circuit applying a voltage to the temperature electrodes of the sensor chip. The biosensor system measures a concentration of an analyte in a blood sample. The biosensor system includes a voltage application unit configured to apply a voltage to the temperature electrodes in accordance with the control circuit, a temperature measuring unit configured to acquire the data a related to the temperature of the blood sample based on the dimension of a current flowing in the temperature electrodes in contact with the blood sample, an analyte measuring unit acquiring data b related to the concentration of the analyte based on the dimension of a current flowing in the blood sample depending on a reaction mediated by an oxidoreductase that uses the analyte in the blood sample as a substrate, and a concentration determination unit configured to determine an analyte concentration in the blood sample based on the data a and the data b.

0076Herein, data a is acquired by direct measurement of the temperature of the blood sample and not through a resin plate or a heat conduction member. The concentration determination unit determines the analyte concentration in the blood sample based on the data a related to the temperature of the blood sample and the data b related to the analyte concentration.

0077In this manner, the production of a measurement error resulting from the temperature of the use environment can be suppressed, and thereby the measurement accuracy of the analyte concentration in the blood sample can be improved.

0078The following biosensor systems are useful for understanding the invention.

0079In a biosensor system , the concentration determination unit includes a first analyte correction unit configured to correct the data b based on the data a.

0080Herein, the first analyte correction unit corrects the data b related to the concentration of the analyte in the blood sample based on the data a acquired by direct measurement of the temperature of the blood sample and not through a resin plate or a heat conduction member.

0081In this manner, the production of a measurement error resulting from the temperature of the use environment can be suppressed, and thereby the measurement accuracy of the analyte concentration in the blood sample can be improved.

0082In a biosensor system the concentration determination unit includes a calculating unit configured to calculate the concentration x of the analyte of the blood sample based on the data b, and a second analyte correction unit configured to correct the concentration x based on the data a.

0083Herein, the analyte correction unit calculates the concentration x of the analyte in the blood sample based on the data b, and then the second analyte correction unit corrects the concentration x based on the data a. acquired by direct measurement of the temperature of the blood sample.

0084In this manner, the production of a measurement error resulting from the temperature of the use environment can be suppressed, and thereby the measurement accuracy of the analyte concentration in the blood sample can be improved.

0085In a biosensor system the concentration determination unit includes a calculating unit configured to calculate the temperature t of the blood sample based on the data a., and a third analyte correction unit configured to correct the data b based on the temperature t.

0086Herein, the calculating unit calculates the temperature t of the blood sample based on the data a. acquired by direct measurement of the temperature of the blood sample, and then the third analyte correction unit corrects the data b based on the temperature t.

0087In this manner, the production of a measurement error resulting from the temperature of the use environment can be suppressed, and thereby the measurement accuracy of the analyte concentration in the blood sample can be improved.

0088<b>In</b> a biosensor system the concentration determination unit includes a calculating unit configured to calculate the temperature t of the blood sample based on the data a, a calculating unit configured to calculate the concentration x of the blood sample based on the data b, and a fourth analyte correction unit configured to correct the concentration x based on the temperature t.

0089Herein, the calculating unit calculates the temperature t of the blood sample based on the data a acquired by direct measurement of the temperature of the blood sample, and calculates the concentration x of the analyte in the blood sample based on the data b, and then the fourth analyte correction unit corrects the concentration x based on the temperature t.

0090In this manner, the production of a measurement error resulting from the temperature of the use environment can be suppressed, and thereby the measurement accuracy of the analyte concentration in the blood sample can be improved.

0091In a biosensor system after acquisition of the data a related to the temperature of the sample by the temperature measuring unit, the data b related to the concentration of the analyte is acquired by the analyte measuring unit.

0092In this manner, the temperature when acquiring the data b can be more accurately reflected.

0093In a biosensor system the concentration determination unit includes a temperature measuring unit configured to acquire data c related to the temperature of the blood sample based on the dimension of a current flowing in the blood sample by application of a predetermined voltage to the pair of electrodes in contact with the blood sample after acquisition of the data b, a computing unit configured to calculate data d related to the temperature of the blood sample based on data a and the data c, and a calculating unit configured to calculate the concentration x of the analyte corrected in response to the temperature of the blood sample based on the data d.

0094In this manner, after acquiring the data b, data c related to the temperature of the blood sample is acquired by the same acquisition method as the data a, and the computing unit calculates the data d related to the temperature of the blood sample based on the data a and the data c. Then the calculating unit corrects the concentration x based on the data d.

0095In this manner, the temperature at the time of acquisition of the data b can be more accurately reflected, and the measurement accuracy of the analyte concentration in the blood sample can be improved.

0096In aa biosensor system, the concentration determination unit includes a temperature calculating unit configured to calculate the temperature t of the blood sample based on the data a, a concentration calculating unit configured to calculate the concentration x of the analyte in the blood sample based on the data b, an environmental temperature measuring unit configured to measure an environmental temperature t1 in a periphery of the blood sample, a comparison unit configured to compare the difference between the temperature t and the environmental temperature t1 with a temperature threshold Z, and a correction unit configured to correct the concentration x based on the temperature t when the relation It - t1 | ≥ Z is satisfied, and correcting the concentration x based on the temperature tl when the relation | t - t1 | &lt; Z is satisfied.

0097Herein, the concentration x of the analyte in the blood sample Is calculated based on the data b, and the temperature of the blood sample Is calculated based on the data a. The environmental temperature t1 in the periphery of the blood sample is measured. Then the difference between the temperature t and the environmental temperature t1 is compared with a temperature threshold Z, and correction is performed as described below.

0098<ul id="ul0004" list-style="none"><li>When | t - t1 | ≥ Z is satisfied, the concentration x is corrected based on the temperature t</li><li>When | t - t1 | &lt; Z is satisfied, the concentration x is corrected based on the temperature t1</li></ul>

0099<b>In</b> this manner, since the concentration x can be corrected using an appropriate temperature in response to an external temperature environment, a measurement accuracy for the analyte concentration in the blood sample can be improved.

0100<b>In</b> a biosensor system a temperature is contained in the data a related to the temperature of the blood sample, and a glucose concentration is contained in the data b related to the concentration of the analyte.

0101Herein, the temperature is included as a feature of the data acquired as data a, and the glucose concentration is included as a feature of the data acquired as the data b.

0102<b>In</b> a biosensor system, hematocrit is included in the data b related to the analyte concentration.

0103Herein, hematocrit is included as a feature of the data acquired as the data b.

0104In a biosensor system of the concentration or amount of the reducing substance is contained in the data b related to the concentration of the analyte.

0105Herein, the amount or concentration of the reducing substance is included as a feature of the data acquired as the data b.

0106A biosensor system further includes a sequence control unit configured to control the control circuit so that at least two features of the data included in the data a and the data b are measured at the same time.

0107Herein, when the data a and the data b are measured, the sequence control unit controls the control circuit so that at least two features of the data are measured at the same time. For example, the sequence control unit controls the control circuit so that the concentration or the amount of the reducing substance and the glucose concentration are measured at the same time.

0108A biosensor systemfurther includes a sequence control unit configured to control the control circuit so that independent measurement of the respective data included in the data a and the data b is executed.

0109Herein, when the data a and the data b are measured, the sequence control unit controls the control circuit so that two or more features of the data are not measured at the same time, but are measured separately. The order of measuring the features may be arbitrary.

0110A biosensor system further includes a sequence control unit configured to control the control circuit so that the measurement of the data contained in the data a and the data b is performed in order of temperature, glucose concentration, concentration or amount of the reducing substance, or hematocrit.

0111Herein, the order of measuring the data is specified. In this manner, effective results can be obtained with respect to speed, accuracy, and burden on the electrodes.

0112A biosensor system further includes an electrode selection unit configured to control the control circuit so that the measurement of the data contained in the data a and the data b is performed through independent electrodes.

0113Herein, when measuring the data contained in the data a and the data b, the electrode selection unit controls the control circuit so that such measurement is performed by respectively independent electrodes.

ADVANTAGEOUS EFFECTS

0114According to the biosensor system, according to the present invention, the production of a measurement error resulting from the temperature of a use environment is suppressed, and improvement of the measurement accuracy of an analyte concentration in a blood sample is enabled.

BRIEF DESCRIPTION OF DRAWINGS

0115<ul id="ul0005" list-style="none"><li><figref idref="f0001">FIG. 1</figref> is a perspective view of a biosensor system useful for understanding the concept of the invention</li><li><figref idref="f0002">FIG. 2</figref> is a partial perspective view of a biosensor chip useful for understanding the concept of the invention.</li><li><figref idref="f0003">FIG. 3</figref> is a through-view plan view of a biosensor chip useful for understanding the concept of the invention.</li><li><figref idref="f0004">FIG. 4</figref> is a circuit diagram in a biosensor system useful for understanding the concept of the invention.</li><li><figref idref="f0005">FIG. 5</figref> is a flowchart illustrating a method for measuring an analyte concentration in a blood sample in the biosensor.</li><li><figref idref="f0006">FIG. 6(a) and 6(b)</figref> is a flowchart illustrating a method for measuring an analyte concentration in a blood sample in the biosensor system and a circuit diagram in a biosensor system useful for understanding the concept of the invention</li><li><figref idref="f0007">FIG. 7(a) and 7(b)</figref> is a flowchart illustrating a method for measuring an analyte concentration in a blood sample in the biosensor system, and a circuit diagram in a biosensor system useful for understanding the concept of the invention.</li><li><figref idref="f0008">FIG. 8(a), 8(b) and 8(c)</figref> are graphs illustrating the variation characteristics of a current obtained by use of the biosensor chip useful for understanding the concept of the invention.</li><li><figref idref="f0009">FIG. 9</figref> is a partial perspective view of a sensor chip useful for understanding the concept of the invention.</li><li><figref idref="f0010">FIG. 10</figref> is a through-view plan view of a sensor useful for understanding the concept of the invention.</li><li><figref idref="f0011">FIG. 11(a), 11(b) and 11(c)</figref> are graphs illustrating the current characteristics of a current corresponding to <figref idref="f0008">FIG. 8</figref> according to Working Example 1.</li><li><figref idref="f0012">FIG. 12</figref> is a graph illustrating the current characteristics obtained in relation to a predetermined temperature according to Working Example 1.</li><li><figref idref="f0013">FIG. 13(a), 13(b), and 13(c)</figref> are graphs illustrating the current characteristics obtained in relation to a predetermined applied voltage and a predetermined hematocrit value when the temperature in Working Example 7 is 4 degrees.</li><li><figref idref="f0014">FIG. 14(a), 14(b), and 14(c)</figref> are graphs illustrating the current characteristics obtained in relation to a predetermined applied voltage and a predetermined hematocrit value when the temperature in Working Example 7 is 13 degrees.</li><li><figref idref="f0015">FIG. 15(a), 15(b), and 15(c)</figref> are graphs illustrating the current characteristics obtained in relation to a predetermined applied voltage and a predetermined hematocrit value when the temperature in Working Example 7 is 21 degrees.</li><li><figref idref="f0016">FIG. 16(a), 16(b), and 16(c)</figref> are graphs illustrating the current characteristics obtained in relation to a predetermined applied voltage and a predetermined hematocrit value when the temperature in Working Example 7 is 30 degrees.</li><li><figref idref="f0017">FIG. 17(a), 17(b), and 17(c)</figref> are graphs illustrating the current characteristics obtained in relation to a predetermined applied voltage and a predetermined hematocrit value when the temperature in Working Example 7 is 38 degrees.</li><li><figref idref="f0018">FIG. 18</figref> is a graph illustrating the relationship with a current value obtained in relation to a predetermined temperature in Working Example 10.</li><li><figref idref="f0019">FIG. 19</figref> is a perspective view illustrating the inter-electrode distance in the sensor chip according to Working Example 11.</li><li><figref idref="f0020">FIG. 20(a) - 20D</figref> are graphs illustrating a response current value by hematocrit, and by inter-electrode distance when the blood sample is 11°C in Working Example 11.</li><li><figref idref="f0021">FIG. 21(a) - 21(d)</figref> are graphs illustrating a response current value by hematocrit, and by inter-electrode distance when the blood sample is 21° C in Working Example 11.</li><li><figref idref="f0022">FIG. 22(a) - 22(d)</figref> are graphs illustrating a response current value by hematocrit, and by inter-electrode distance when the blood sample is 30 ° C in Working Example 11.</li><li><figref idref="f0023">FIG. 23(a) and 23(b)</figref> is a perspective view illustrating a sensor chip according to Working Example 12.</li><li><figref idref="f0024">FIG. 24(a) and 24(b)</figref> are graphs illustrating a response current value by hematocrit, and by electrode shape when the blood sample is 11° C in Working Example 12.</li><li><figref idref="f0025">FIG. 25(a) and 25(b)</figref> are graphs illustrating a response current value by hematocrit, and by electrode shape when the blood sample is 21° C in Working Example 12.</li><li><figref idref="f0026">FIG. 26(a) and 26(b)</figref> are graphs illustrating a response current value by hematocrit, and by electrode shape when the blood sample is 30° C in Working Example 12.</li><li><figref idref="f0027">FIG. 27(a) and 27(b)</figref> is a perspective view illustrating a sensor chip according to Working Example 13.</li><li><figref idref="f0028">FIG. 28(a) - 28(d)</figref> are graphs illustrating a response current value by hematocrit, and by lead width when the blood sample is 30 ° C in Working Example 13.</li><li><figref idref="f0029">FIG. 29</figref> is a perspective view illustrating the capillary height in the sensor chip in Working Example 14.</li><li><figref idref="f0030">FIG. 30(a) and 30(b)</figref> are graphs illustrating a response current value by hematocrit, and by capillary height when the blood sample is 11° C in Working Example 14.</li><li><figref idref="f0031">FIG. 31(a) and 31(b)</figref> are graphs illustrating a response current value by hematocrit, and by capillary height when the blood sample is 21° C in Working Example 14.</li><li><figref idref="f0032">FIG. 32(a) and 32(b)</figref> are graphs illustrating a response current value by hematocrit, and by capillary height when the blood sample is 30° C in Working Example 14.</li><li><figref idref="f0033">FIG. 33(a) and 33(b)</figref> are graphs illustrating a response current value by palladium resistance when the blood sample is 4 ° C in Working Example 15.</li><li><figref idref="f0034">FIG. 34(a) and 34(b)</figref> are graphs illustrating a response current value by palladium resistance when the blood sample is 13° C in Working Example 15.</li><li><figref idref="f0035">FIG. 35(a) and 35(b)</figref> are graphs illustrating a response current value by palladium resistance when the blood sample is 21° C in Working Example 15.</li><li><figref idref="f0036">FIG. 36(a) and 36(b)</figref> are graphs illustrating a response current value by palladium resistance when the blood sample is 30 ° C in Working Example 15.</li><li><figref idref="f0037">FIG. 37(a) and 37(b)</figref> are graphs illustrating a response current value by palladium resistance when the blood sample is 38° C in Working Example 15.</li><li><figref idref="f0038">FIG. 38</figref> is a graph illustrating response current value by glucose concentration when the blood sample is 24 ° C in Working Example 15.</li><li><figref idref="f0039">FIG. 39</figref> is a graph illustrating response current value by ascorbic acid concentration when the blood sample is 24° C in Working Example 17.</li><li><figref idref="f0040">FIG. 40</figref> is a graph illustrating response current value by temperature when the blood sample is introduced in an environment of 24 ° C in Working Example 18.</li><li><figref idref="f0041">FIG. 41</figref> is a perspective view illustrating the upward orientation and downward orientation of the sensor chip according to Working Example 19.</li><li><figref idref="f0042">FIG. 42</figref> is a graph illustrating a response current value when blood is attached in an upward orientation and a downward orientation in an environment of 24 °C according to Working Example 19.</li><li><figref idref="f0043">FIG. 43</figref> is a graph illustrating a response current value when a distal end portion of the sensor chip is held between the fingers and not held between the fingers in an environment of 24 ° C according to Working Example 20.</li><li><figref idref="f0044">FIG. 44</figref> illustrates a measurement sequence in Working Example 21.</li><li><figref idref="f0045">FIG. 45(a)</figref> is a graph illustrating a response current value for glucose measured in Working Example 21, and <figref idref="f0045">FIG. 45(b)</figref> is a graph illustrating a response current value for temperature and Hct measured in Working Example 21.</li><li><figref idref="f0046">FIG. 46(a)</figref> is a graph illustrating a response current value for temperature measurement in Working Example 21, and <figref idref="f0045">FIG. 45(b)</figref> is a graph illustrating a response current value by temperature when temperature is measured in Working Example 21.</li><li><figref idref="f0047">FIG. 47</figref> illustrates another measurement sequence in Working Example 21.</li><li><figref idref="f0048">FIG. 48(a) and FIG. 48(b)</figref> is a flowchart illustrates a measurement method for analyte concentration in a blood sample in a biosensor system according to a first modified example.</li><li><figref idref="f0049">FIG. 49(a) and FIG. 49(b)</figref> is a flowchart illustrates a measurement method for analyte concentration in a blood sample in a biosensor system according to the first modified example.</li><li><figref idref="f0050">FIG. 50(a) and FIG. 50(b)</figref> is a circuit diagram for a biosensor system according to the first modified example.</li><li><figref idref="f0051">FIG. 51(a) and FIG. 51(b)</figref> is a circuit diagram for a biosensor system according to the first modified example.</li><li><figref idref="f0052">FIG. 52</figref> is a circuit diagram for a biosensor system according to a second modified example.</li><li><figref idref="f0053">FIG. 53</figref> is a circuit diagram for a biosensor system.</li></ul>

DESCRIPTION OF EMBODIMENTS

0116A biosensor acquires the temperature of the analyte from the blood sample by a measuring unit disposed in the sensor chip.

0117<figref idref="f0001">FIG. 1</figref> illustrates an example of a biosensor system useful for understanding the concept of the invention. The biosensor system 100 includes a rectangular parallelepiped measuring device 101 and a sensor chip 200. A mounting port 102 configured as a rectangular hole is formed in a side wall surface of the measuring device 101. The sensor chip 200 is connected to the measuring device 101 that is detachably attached to the mounting port 102. The display unit 103 that displays the measurement results is disposed in a substantially central portion of one major surface of the measuring device 101.

0118<figref idref="f0002">FIG. 2</figref> is a partial perspective view of the sensor chip 200. <figref idref="f0003">FIG. 3</figref> is a plan view thereof. In the sensor chip 200, a cover 203 is disposed on an insulating plate 201 through a spacer 202 that forms a rectangular notch 204, and leaves one end portion of the insulating plate 201 (the right end in <figref idref="f0002">FIG. 2</figref>).

0119Each member 201, 202, 203 is integrated for example by adhesion or thermal welding. After integration of each of the members, the notch 204 of the spacer 202 functions as a capillary 40 that retains the blood sample. The capillary 40 has an elongated shape along the long side of the sensor chip 200, and communicates with an outer portion on one end portion of the spacer 202 (the left end portion in <figref idref="f0002">FIG. 2</figref> and <figref idref="f0003">FIG. 3</figref>). In other words, the capillary 40 communicates with the blood sample introduction port 17 that opens onto an outer portion of the sensor chip 200. The cover 203 includes a discharge port 16 in proximity to the opposite end to the side near the blood sample introduction port 17 in the capillary 40. In this manner, the blood sample is easily aspirated by capillary action from the blood sample introduction port 17 into an inner portion of the capillary 40.

0120Respective portions (portions 31, 32, 33, 34, 35) of the electrodes (voltage application portion) 11, 12, 13, 14, 15 are disposed on an insulating plate 201 to face the capillary 40. The portion 31 of the electrode 11 and the portion 32 of the electrode 12 are disposed at a position in closer proximity to the blood sample introduction port 17 than the portion 33 of the electrode 13 and the portion 34 of the electrode 14.

0121A reaction reagent layer 20 is formed on the insulating plate 201 to cover the whole of the portion 33 of the electrode 13 and to partially cover the portion 34 of the electrode 14 and the portion 35 of the electrode 15. The reaction reagent layer 20 includes an oxidoreductase that uses the analyte in the blood sample as a substrate, and an electron mediator.

0122The reaction reagent layer 20 is formed at a position separated from the portion 31 of the electrode 11 and the portion 32 of the electrode 12. It is preferred that a reagent including an oxidoreductase or an electron mediator is not disposed on the portion 31 of the electrode 11 and the portion 32 of the electrode 12, and more preferably no reagent is disposed.

0123In an opposite configuration to the above (not forming part of the invention), when the portion 33 of the electrode 13 and the portion 34 of the electrode 14 are disposed at a position in closer proximity to the blood sample introduction port 17 than the portion 31 of the electrode 11 and the portion 32 of the electrode 12, if the blood sample is introduced from the blood sample introduction port 17, the sample may reach the portion 33 of the electrode 13 and the portion 34 of the electrode 14 due to flow in the reaction reagent layer 20 on the portion 33 of the electrode 13 and the portion 34 of the electrode 14. Therefore, this configuration should be avoided.

0124The sensor chip 200 includes a measuring unit 41 (measuring unit A). The measuring unit A is configured from an electrode system (temperature electrodes) formed by the portion 31 of the electrode 11 and the portion 32 of the electrode 12, and a space in a portion of the capillary 40 that contains the portion 31 and the portion 32.

0125The sensor chip 200 includes a measuring unit 42 (measuring unit B). The measuring unit B is configured from an electrode system (analysis electrodes) formed by the portion 33 of the electrode 13 and the portion 34 of the electrode 14, and a space in a portion of the capillary 40 that contains the reaction reagent layer 20 in addition to the portion 33 and the portion 34.

0126In the temperature electrodes of the measuring unit A, the electrode 11 functions as a working electrode and the electrode 12 functions as an counter electrode. In the analysis electrodes of the measuring unit B, the electrode 13 functions as a working electrode and the electrode 14 functions as an counter electrode.

0127The measuring unit A (temperature measuring unit) acquires the data a related to the temperature of the blood sample based on the amount of current flowing in the temperature electrodes. The substance that exhibits an electrochemical reaction on the temperature electrodes is mainly a component of the blood sample, or may be water, or may be a blood-cell component such as red blood cells or white blood cells.

0128The measuring unit B (analyte measuring unit) acquires the data b related to the concentration of the analyte in the blood sample based on the amount of current flowing in the analysis electrodes. The substance that exhibits an electrochemical reaction on the analysis electrodes is mainly an electron mediator that exchanges electrons with the oxidoreductase. The data b acquired in the measuring unit B is corrected based on the temperature using the data a. The concentration of the analyte is calculated using the data b after correction.

0129One or both of the portion 33 of the electrode 13 and the portion 34 of the electrode 14 may function as one or both of the portion 31 of the electrode 11and a portion 32 of the electrode 12. However it is preferred that these electrodes are provided separately.

0130The portion 35 of the electrode 15 is disposed in proximity to the inner end portion of the capillary 40, that is to say, in proximity to the opposite end to the end that communicates with the outer portion. Application of voltage between the electrode 15 and the electrode 13 facilitates detection when the blood sample is introduced to an inner portion of the capillary 40. The voltage may be applied between the electrode 14 and the electrode 15 in substitution for the electrode 13.

0131The electrodes 11, 12, 13, 14, 15 are connected with respective leads (not illustrated). One end of the lead is exposed to an outer portion of the sensor chip 200 on the end portion of the insulating plate 201 that is not covered by the spacer 202 and the cover 203 to thereby enable application of a voltage between each electrode.

0132According to the invention, the analyte in the blood sample is glucose. The oxidoreductase may be a substance that uses the target analyte as a substrate. The oxidoreductase may be exemplified by glucose oxidase and glucose dehydrogenase. The amount of the oxidoreductase in the reaction reagent layer is 0.01 - 100 units (U), preferably 0.05 - 10 U, and more preferably 0.1- 5 U.

0133The reaction reagent layer 20 contains an electron mediator that has a function of exchanging electrons produced by an oxidation reaction with an electrode, such as potassium ferricyanide, p·benzoquinone, p·benzoquinone derivatives, oxidized phenazine methosulfate, methylene blue, ferricinium and ferricinium derivatives. The reaction reagent layer 20 may include a water soluble polymer compound to increase molding characteristics of the reaction reagent layer. The water soluble polymer compound may be exemplified from at least one selected from the group consisting of carboxymethyl cellulose and salts thereof, hydroxyethyl cellulose, hydroxypropylcellulose, methylcellulose, ethylcellulose, ethylhydroxyethyl cellulose, carboxymethyl cellulose and salts thereof, polyvinylalcohol, polyvinylpyrrolidone, polyamino acids such as polylysine, polystyrenesulfonic acid and salts thereof, gelatin and derivatives thereof, polyacrylic acid and salts thereof, polymethacrylate and salts thereof, starch and derivatives thereof, maleic anhydride polymers and salts thereof, and agarose gel and derivatives thereof.

0134The material of the insulating plate 201, the spacer 202 and the cover 203 is exemplified by polyethylene terephthalate, polycarbonate, polyimide, 10 polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyoxymethylene, monomer-cast nylon, polybutylene terephthalate, resins such as methacrylate resin and ABS resin, and glass.

0135The electrodes 11, 12, 13, 14, and 15 for example are configured from a known conductive material such as palladium, platinum, gold, silver, titanium, copper, nickel, and carbon.

0136<figref idref="f0004">FIG. 4</figref> illustrates an example of a circuit configuration for measuring an analyte concentration in a blood sample in the biosensor system 100. The measuring device 101 includes a control circuit 300 that applies a voltage between at least two electrodes of the electrodes 11, 12, 13, 14 and 15 in the sensor chip 200, and a display unit 400 that displays the measurement result.

0137The control circuit 300 includes five connectors 301a, 301b, 301c, 301d, 301e, a switching circuit 302, a current/voltage conversion circuit 303, an analog/digital (AID) conversion circuit 304, a reference voltage power source 305, and a computing unit 306. The control circuit 300 enables switching of the potential applied to the electrodes to enable use of one electrode as a cathode or as an anode through the switching circuit 302.

0138The computing unit (concentration determination unit) 306 includes a known central processing unit (CPU) and a conversion table for determining an analyte concentration in a blood sample based on the data a and the data b. The computing unit 306 uses a correction coefficient based on the environmental temperature to correct the analyte concentration by reference to the conversion table above. More specifically, after referring to the conversion table for preliminary measurement and provisionally calculating the analyte concentration, the computing unit 306 corrects the analyte concentration by reference to a conversion table for temperature correction.

0139As illustrated in <figref idref="f0005">FIG. 5</figref>, the measurement of the analyte concentration in the blood sample using the biosensor system 100 for example is executed as described below.

0140Firstly, the CPU in the computing unit 306 commands the electrode 13 to connect with the current/voltage conversion circuit 303 through the connector 301b and the electrode 15 to connect with the reference voltage power source 305 through the connector 30 le.

0141Thereafter, the CPU commands the application of a predetermined voltage to both electrodes (step SI). For example, when the voltage is denoted by the electrode 15 as the positive electrode and the electrode 13 as the negative electrode, the voltage is 0.01 - 2.0V, preferably 0.1 - 1.0V, and more preferably 0.2 - 0.5V.The voltage is applied from insertion of the sensor chip into the measuring device 101 until the introduction of the blood sample into an inner portion of the capillary 40. When the blood sample is introduced into the capillary 40 from the blood sample introduction port of the sensor chip 200, a current flows between the electrode 15 and the electrode 13. The CPU detects that the capillary 40 is filled with the blood sample by discrimination of an increase amount in the current per unit time during this period. The current value is converted to a voltage value by the current/voltage conversion circuit 303 and then is converted to a digital value by the AID conversion circuit 304 and and input to the CPU. The CPU detects that the blood sample is introduced into the inner portion of the capillary based on the digital value.

0142After introduction of the blood sample, for example, the analyte in the blood sample and oxygen, and oxygen and the electron mediator are reacted within a range of 0 - 60 seconds, preferably 0 - 15 seconds, and more preferably 0 - 5 seconds.

0143Then, the data a is acquired in the following manner (step 82).

0144Firstly, the voltage switching circuit 302 is operated by command of the CPU, the electrode 11 is connected with the current/voltage conversion circuit 303 through the connector 301a, and the electrode 12 is connected with the reference voltage power source 305 through the connector 301e. Then the CPU commands application of a predetermined voltage between the electrodes in the measuring unit A. As described below, when the voltage is denoted using the electrode 11 as the positive electrode and the electrode 12 as the negative electrode, the voltage is in the range of 0.1 - 5.0V, preferably 1.0 - 3.0V, and more preferably 1.5 - 2.5V. The voltage application time is in the range of 0.1- 30 seconds, preferably from 0.5 - 10 seconds, and more preferably 1- 5 seconds. A signal commanding acquisition of the data a is output from the control circuit to the measuring unit A, to thereby cause the current/voltage conversion circuit 303 to convert the current amount between both electrodes resulting from application of the voltage to a voltage amount. Thereafter, the voltage amount is converted to a digital value by the AID conversion circuit 304, inputted to the CPU, and stored in the memory of the computing unit 306 as the data a.

0145Thereafter, the data b is acquired as described below (step 83).

0146Firstly, the voltage switching circuit 302 is operated by command of the CPU, the electrode 13 is connected with the current/voltage conversion circuit 303 through the connector 301b, and the electrode 14 is connected with the reference voltage power source 305 through the connector 301d. Then, the CPU commands commencement of the measurement sequence in the measuring unit B. The voltage applied at this time is denoted using the electrode 13 as the positive electrode and the electrode 14 as the negative electrode, and is in the range of 0.05 - 1.0V, preferably 0.1 - 0.8V, and more preferably 0.2 - 0.6V. The voltage application time is from 0.1 - 30 seconds, preferably from 0.1 - 15 seconds, and more preferably 0.1 - 5 seconds. A signal commanding acquisition of the data b is output from the control circuit to the measuring unit B, and thereby cause the current/voltage conversion circuit 303 to convert the current amount flowing between both electrodes as a result of the voltage application to a voltage amount. Thereafter the voltage is converted to a digital value by the AID conversion circuit 304, inputted to the CPU, and stored in the memory of the computing unit 306 as data b. From the point of view of enhancing the measurement speed of the analyte concentration, the control circuit preferably applies the signal commanding acquisition of the data b to the measuring unit B within a range of at least 0.5 seconds and less than 5 seconds from the time that the blood sample is introduced into the capillary 40 of the sensor chip.

0147The data b may be acquired prior to acquisition of the data a. However, pr10r to acquisition of the data b, since a sufficient period is required for dissolution of the sample, oxygen reaction of the electron mediator with oxygen, and the like, the data b is preferably acquired after acquisition of the data a. Furthermore, the data b and the data a may be acquired simultaneously. However, since a voltage is applied simultaneously to two groups of electrode systems in one solution system, there may be interference between the respective currents. Consequently, separate acquisition of the data a and acquisition of the data b is preferred.

0148As illustrated in <figref idref="f0006">FIG. 6(a)</figref>, the temperature when acquiring the data b is more accurately reflected in the temperature measurement results by respectively acquiring data related to temperature of the blood sample before and after the acquisition of the data b. In other words, the biosensor system 100 applies a predetermined voltage to both electrodes (step 8101), acquires the data a related to the temperature of the blood sample (step 8102), and then acquires the data b related to the concentration of the analyte in the blood sample (step 8103). Thereafter, the data c related to the temperature of the blood sample is reacquired (step 8104). Then, the computing unit 306 calculates the data d by calculation of the average of the data a and the data c (step 8105), and calculates the analyte concentration by correcting the temperature in the data b using the data d (step 8106). As illustrated in <figref idref="f0006">FIG. 6(b)</figref>, the computing unit (concentration determination unit) 306 (refer to <figref idref="f0004">FIG. 4</figref>) in the biosensor system 100 includes a temperature measuring unit 307 that acquires the data c related to the temperature of the blood sample based on the dimension of the current flowing through the temperature electrodes that is in contact with the blood sample after acquisition of the data b, a computing unit 308 that calculate the data d related to the temperature of the blood sample based on the data a and the data c, and a concentration calculating unit 309 that uses the data d to calculate the concentration x of the analyte that is corrected in response to the temperature of the blood sample.

0149Then the computing unit 306 refers to the convers10n table and determines the analyte concentration in the blood sample based on the data a the data b (step 84). The determined analyte concentration is displayed on the display unit 400. If a temperature conversion table is prepared in relation to the data a, the computing unit 306 can calculate the temperature of the blood sample, and can display the temperature on the display unit 400. A computing program used in this determination may be suitably designed in response to the data structure of the conversion table. When numerical data displaying a complete correspondence with the data a and the data b is not stated in the conversion table, the computing unit 306 may determine the analyte concentration using data stated in the conversion table and a known interpolation method using data that approximates the data a and the data b.

0150If required, use of the electrode 11 and the electrode 12 may be used as an electrode for temperature measurement applications and an electrode for other analyte applications. The other analyte application for example includes measurement of a hematocrit value in the blood sample, and measurement of a reducing substance such as ascorbic acid, uric acid, bilirubin, acetaminophen, and the like. A method of using the electrode 11 or the electrode 12 as the working electrode (positive electrode), the electrode 13 or the electrode 14 as the counter electrode (negative electrode) is known.

0151The voltage between the temperature electrodes in the measuring unit A is affected by the configuration of the sensor chip such as the electrode material or the electrode surface area, and therefore it is necessary to determine an optimal applied voltage in advance. The current amount acquired when applying a voltage that diverges from an optimal value is affected by the hematocrit value (Hct value) in the blood sample. An Hct value means a numerical value expressing the ratio of the content of blood cells in blood.

0152When the optimal voltage value is denoted as Vm, a voltage value higher than the optimal voltage value is denoted as Vh, and a voltage value lower than the optimal voltage value is denoted as VI, the change in the current amount expressed by (VI&lt;Vm&lt;Vh) is illustrated in <figref idref="f0008">FIG. 8</figref>. When a voltage value VI that is lower than the optimal voltage value is applied, as illustrated in <figref idref="f0008">FIG. 8(a)</figref>, the current amount increases as the value Hct increases. Conversely, when the voltage value Vh is higher than the optimal voltage value is applied, as illustrated in FIG. S(c), the current amount increases as the Hct value decreases. When the optimal voltage value Vm is used, as illustrated in <figref idref="f0008">FIG. 8(b)</figref>, a fixed current amount is exhibited irrespective of the Hct value. A conspicuous estrangement of the current amount resulting from the Hct value is exhibited under high temperature conditions and a high current amount. Therefore the upper limiting temperature in the temperature measurement region is preferably determined in advance. The Vm range is 0.1 - 5.0 V, preferably 1.0 - 3.0 V, and more preferably 1.5 - 2.5 V.

0153The current amount flowing between the temperature electrodes in the measuring unit A is affected by the electrode surface area. A higher current amount is obtained when either of the surface area of a portion 31 of the electrode 11 (working electrode) and the surface area of a portion 32 of the electrode 12 (counter electrode) is increased. However it is preferred to increase the surface area of the portion 32 that is on the counter electrode side. More specifically, the range of the proportion of the surface area of the working area/the surface area of the counter electrode is preferably 1 - 0.25.

0154Even when there is a rapid change in the environmental temperature of the sensor, the biosensor system according to the embodiment enables highly accurate measurement of the analyte concentration. As a result, there is no necessity to provide an environmental temperature measuring unit such as a thermistor in the measuring device.

0155However, the state or configuration of the sensor may result in a low accuracy in relation to the current amount obtained by the measuring unit A. For example, in a sensor that has a small surface-area capillary 40, although the capacity of the blood sample required for measurement may be reduced, the surface area of the temperature electrodes in the measuring unit A must be reduced. Therefore, the current amount obtained in the measurement A is decreased, and as a result, it is predicted that the accuracy of the current amount obtained in the measuring unit A will be reduced. In this case, as illustrated in the circuit configuration diagram in <figref idref="f0053">FIG. 53</figref>, the environmental temperature measuring unit 315 may be provided in the measuring device. The number of environmental temperature measuring units 315 may be only one, or may be two or more. When two or more environmental temperature measuring units 315 are provided, respective environmental temperature measuring units 315 guarantee a more accurate measurement result for the environmental temperature by mutually monitoring of accuracy.

0156Furthermore, when temperature data obtained by the measuring unit A in the sensor is compared with the temperature data obtained from a thermistor provided in the measuring device, temperature correction may be executed and the respective temperature change can be monitored, an optimal temperature can be selected, and used for temperature correct. Furthermore, a method may be used in which the temperature is corrected by reference to the difference between the temperature of the measuring unit A and the temperature of the thermistor, or a method in which a plurality of temperature differences is acquired, and an optimal temperature correction value is selected. Of course, a method of utilizing data for average values and not temperature differences may be executed.

0157In the biosensor system 100 illustrated in <figref idref="f0053">FIG. 53</figref>, the computing unit 306 compares the temperature t acquired by the measuring unit A and the temperature t1 acquired by the environmental temperature measuring unit 315 in the measuring device (step 843), and uses the temperature t acquired by the measuring unit A only when there is an error between the two. That is to say, as illustrated in <figref idref="f0007">FIG. 7(a)</figref>, the computing unit 306 calculates the temperature t based on the data a (step S41). The computing unit 306 calculates the concentration x based on the data b (step S42). The environmental temperature measuring unit 315 measures the environmental temperature t1 (step S43).

0158When there 1s no difference between the outer environmental temperature and the blood sample temperature, the computing unit 306 uses the temperature t1 (step 845) since the environmental temperature measuring unit 315 has a high measurement accuracy.

0159When there is a difference between the outer environmental temperature and the blood sample temperature as a result of a sharp variation in the temperature, the environmental temperature measuring unit 315 cannot adapt to the difference. Therefore, the temperature t acquired by the measuring unit A is adopted (step S46). More specifically, the temperature threshold Z is preset. The computing unit 306 is compares the value for |t - t1| with the temperature threshold Z (step S44). When the value for | t - t1 | is higher than or equal to the temperature threshold Z, the computing unit 306 corrects the concentration x based on the temperature t (step S45). When smaller than the temperaturethreshold Z, the concentration x is corrected based on the environmental temperature tI (step S46).

0160The range of the temperature threshold Z is determined in consideration of the accuracy of the environmental temperature measuring unit of the measuring device and the accuracy of the measuring unit A in the sensor chip, and is in the range of 0.01 - 5.0° C, preferably 0.1 - 2.0° C, and more preferably 0.2 - I.0° C.

0161As illustrated m <figref idref="f0007">FIG. 7(b)</figref>, the computing unit (concentration determination unit) 306 in the biosensor system 100 (refer to <figref idref="f0004">FIG. 4</figref> and <figref idref="f0052">FIG. 52</figref>) includes a temperature calculating unit 310 and a concentration calculating unit 311. The temperature calculating unit 310 calculates the temperature t of the blood sample based on the data a. The concentration calculating unit 311 calculates the concentration x of the analyte of the blood sample based on the data b.

0162The measuring device includes an environmental temperature measuring unit 312, a comparison unit 313, and a correction unit 314. The environmental temperature measuring unit 312 measures the peripheral environmental temperature t1 of the blood sample. The comparison unit 313 compares the difference between the temperature t and the environmental temperature t1 with the temperature threshold value Z. The correction unit 314 corrects the concentration x based on the temperature t when the expression |t - t1 | ≥ Z is satisfied, and corrects the concentration x based on the environmental temperature t1 when the expression | t - t1 | &lt; Z is satisfied.

[Working Examples]

0163The invention will be illustrated in further detail below with reference to the embodiments.

0164The following working examples and modified examples are useful for understanding the concept of the invention.

[Working Example 1]

0165A sensor chip 210 is prepared as illustrated in <figref idref="f0009">FIG. 9</figref> and <figref idref="f0010">FIG. 10</figref>. The capillary is designed with a width of 1.2 mm, a length (depth) of 4.0 mm, and a height of 0.15 mm. The insulating plate is formed from polyethylene terephthalate. After palladium is deposited by vapor deposition onto the insulating plate, the respective electrodes were formed by formation of a slit in the palladium layer with a laser so that the surface area of the portion 31 of the electrode 11 is 0.12 mm2, and the portion 32 of the electrode 12 is 0.48 mm2.

0166Three types of blood samples having Hct values respectively of 25%, 45% and 65% were prepared. The temperature of the blood sample was taken to be 23 ° C. These blood samples were introduced into the capillary of separate sensor chips. Thereafter, the electrode 11 was used as the working electrode (positive electrode) and the electrode 12 was used as the counter electrode (negative electrode), and a voltage of 2.0V, 2.2V, or 2.4V was applied between the electrodes (temperature electrodes). The current flowing between the working electrode and the counter electrode (response current) due to application of the voltage is measured.

0167The measurement results are illustrated in the graphs in <figref idref="f0011">FIG. 11(a), FIG. 11(b), and FIG. 11(c)</figref>.

0168When the applied voltage is 2.0V, as illustrated in FIG. II(a), the response current increases as the Hct value increases. These results correspond to <figref idref="f0008">FIG. 8(a)</figref>.

0169As illustrated in <figref idref="f0011">FIG. 11(b)</figref>, when the applied voltage is 2.2V, the response current is fixed irrespective of the Hct value. These results correspond to <figref idref="f0008">FIG. 8(b)</figref>.

0170As illustrated m <figref idref="f0011">FIG. 11(c)</figref>, when the applied voltage is 2.4V, the response current increases as the Hct value decreases. These results correspond to <figref idref="f0008">FIG. 8(c)</figref>.

0171Next, an experiment using a blood sample with an Hct 45% at 4 °C 38 °C was performed. At each temperature, the blood sample was introduced into the capillary of separate sensor chips. Thereafter, the electrode 11 was used as the working electrode (positive electrode) and the electrode 12 was used as the counter electrode (negative electrode), and the response current was measured when a voltage of 2.2V was applied between the electrodes (temperature electrodes). The measurement results are illustrated in the graph in <figref idref="f0012">FIG. 12</figref>. As illustrated in <figref idref="f0012">FIG. 12</figref>, the response current increases as the temperature increases.

0172The results in <figref idref="f0011">FIG. 11</figref> and <figref idref="f0012">FIG. 12</figref> demonstrate that a blood sample temperature can be detected by applying a large voltage of 2.2V between the electrode 11 and the electrode 12 and thereby measuring the response current.

[Working Example 2]

0173The sensor chip having the configuration described in Working Example 1was used, and a blood sample at a temperature of 23 ° C and an Hct value of 45% was introduced into the capillary of the sensor chip. Thereafter, the electrode 11 was used as the working electrode (positive electrode) and the electrode 12 was used as the counter electrode (negative electrode), and the response current was measured when a voltage of 2.2V was applied between the electrodes (temperature electrodes). Table 1 below illustrates the current value after three seconds from initiation of voltage applicaton. The current value in Working Example 2 was 1.88µA. <tables id="tabl0001" num="0001"><table frame="all"><title>Table 1</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="32mm" /><colspec colnum="2" colname="col2" colwidth="30mm" /><colspec colnum="3" colname="col3" colwidth="29mm" /><colspec colnum="4" colname="col4" colwidth="31mm" /><colspec colnum="5" colname="col5" colwidth="41mm" /><thead valign="top"><row><entry morerows="1" align="center" /><entry namest="col2" nameend="col3" align="center">Electrode Surface Area (mm²)</entry><entry morerows="1" align="center">Current Value (µA)</entry><entry morerows="1" align="center">Current Increase Rate (%)</entry></row><row><entry align="center">Working Electrode</entry><entry align="center">Counter electrode</entry></row></thead><tbody><row><entry align="center">Working Example 2</entry><entry align="center">0.12</entry><entry align="center">0.48</entry><entry align="center">1.88</entry><entry align="center">-</entry></row><row><entry align="center">Working Example 3</entry><entry align="center">0.24</entry><entry align="center">0.48</entry><entry align="center">2.47</entry><entry align="center">32</entry></row><row><entry align="center">Working Example 4</entry><entry align="center">0.48</entry><entry align="center">0.48</entry><entry align="center">3.13</entry><entry align="center">67</entry></row><row><entry align="center">Working Example 5</entry><entry align="center">0.12</entry><entry align="center">0.96</entry><entry align="center">3.08</entry><entry align="center">65</entry></row><row><entry align="center">Working Example 6</entry><entry align="center">0.24</entry><entry align="center">0.90</entry><entry align="center">3.65</entry><entry align="center">94</entry></row></tbody></tgroup></table></tables>

[Working Example 3]

0174An electrode was formed so that the surface area of the portion 31 of the electrode 11 of the sensor chip is 0.24 mm2, and the surface area of the portion 32 of the electrode 12 of the sensor chip is 0.48 mm2. Other conditions are the same as the sensor chip described in Working Example 2. Table 1 below illustrates the current value after three seconds from initiation of voltage application. The current value in Working Example 3 was 2.47 µA. When compared with Working Example 2, the current value exhibits a 32% increase. The surface area of the working electrode in the sensor chip in Working Example 3 is twice as large when compared with Working Example 2.

[Working Example 4]

0175An electrode was formed so that the surface area of the portion 31 of the electrode 11 of the sensor chip is 0.48 mm2, and the surface area of the portion 32 of the electrode 12 of the sensor chip is 0.48 mm2. Other conditions are the same as the sensor chip described in Working Example 2. Table 1 below illustrates the current value after three seconds from initiation of voltage application. The current value in Working Example 4 was 3.13 µA. When compared with Working Example 2, the current value exhibits a 67% increase. The surface area of the working electrode in the sensor chip in Working Example 4 is four times as large when compared with Working Example 2 and twice as large when compared with Working Example 3. In other words, it is shown that the current value increases as the surface area of the working electrode increases.

[Working Example 5]

0176An electrode is formed so that the surface area of the portion 31 of the electrode 11 of the sensor chip is 0.12 mm2, and the surface area of the portion 32 of the electrode 12 of the sensor chip is 0.96 mm2. Other conditions are the same as the sensor chip described in Working Example 2. Table 1 below illustrates the current value after three seconds from initiation of voltage application. The current value in Working Example 5 was 3.08 µA. When compared with Working Example 2, the current value exhibits a 65% increase. The surface area of the working electrode in the sensor chip in Working Example 5 is twice as large when compared with Working Example 2. In other words, it is shown that the current value increases as the surface area of the counter electrode increases. When compared with Working Example 3, the increase rate in the current value only reaches 32% under the condition that the surface area of the working electrode is two times. Therefore a higher response value is obtained by increasing the surface of the counter electrode more than the working electrode.

[Working Example 6]

0177An electrode is formed so that the surface area of the portion 31 of the electrode 11 of the sensor chip is 0.24 mm2, and the surface area of the portion 32 of the electrode 12 of the sensor chip is 0.96 mm2 .Other conditions are the same as the sensor chip described in Working Example 2. Table 1 below illustrates the current value after three seconds from initiation of voltage application. The current value in Working Example 6 was 3.65 µA. When compared with Working Example 2, the current value exhibits a 94% increase. The surface area of the working electrode and the counter electrode in the sensor chip in Working Example 6 is twice as large when compared with Working Example 2. In other words, the current value is also increased in proportion to an increase in the electrode surface area when the ratio of the electrode surface areas is the same.

[Working Example 7]

0178A sensor chip as described in Working Example 1is prepared. Fifteenth types of blood samples being combinations of three Hct values respectively of 25%, 45% and 65% and five temperatures of 4° C, 13° C, 21 ° C, 30° C, and 38° C were prepared.

0179These blood samples were introduced into the capillary of separate sensor chips. Next, the electrode 11 was used as the working electrode (positive electrode) and the electrode 12 was used as the counter electrode (negative electrode), and a voltage of 2.IV, 2.15V, or 2.2V was applied between the electrodes (temperature electrodes) to thereby measure the response current at that time.

0180<figref idref="f0013 f0014 f0015 f0016 f0017">FIG. 13 to FIG. 17</figref> are graphs illustrating the response current at respective temperature conditions and applied voltages. The temperature conditions and the applied voltage conditions in each graph are as illustrated below.

(Temperature Condition)

0181<ul id="ul0006" list-style="none" compact="compact"><li><figref idref="f0013">FIG. 13(a), 13(b), 13(c)</figref>: 4° C</li><li><figref idref="f0014">FIG. 14(a), 14(b), 14(c)</figref>: 13° C</li><li><figref idref="f0015">FIG. 15(a), 15(b), 15(c)</figref>: <figref idref="f0021">21</figref> ° C</li><li><figref idref="f0016">FIG. 16(a), 16(b), 16(c)</figref>: 30° C</li><li><figref idref="f0017">FIG. 17(a), 17(b), 17(c)</figref>: <figref idref="f0038">38</figref> ° C</li></ul>

(Applied Voltage Condition)

0182<ul id="ul0007" list-style="none" compact="compact"><li><figref idref="f0013">FIG. 13(a)</figref>, <figref idref="f0014">FIG. 14(a)</figref>, <figref idref="f0015">FIG. 15(a)</figref>, <figref idref="f0016">FIG. 16(a)</figref>, <figref idref="f0017">FIG. 17(a)</figref>: 2100mV</li><li><figref idref="f0013">FIG. 13(b)</figref>, <figref idref="f0014">FIG. 14(b)</figref>, <figref idref="f0015">FIG. 15(b)</figref>, <figref idref="f0016">FIG. 16(b)</figref>, <figref idref="f0017">FIG. 17(b)</figref>: 2150mV</li><li><figref idref="f0013">FIG. 13(c)</figref>, <figref idref="f0014">FIG. 14(c)</figref>, <figref idref="f0015">FIG. 15(c)</figref>, <figref idref="f0016">FIG. 16(c)</figref>, <figref idref="f0017">FIG. 17(c)</figref>: 2200mV</li></ul>

0183Under the low temperature conditions of 4 ° C and 13° C in which the response current is small, a response current that is not dependent in the Hct value is exhibited in the same manner under any of the applied voltage conditions.

0184Under the high temperature conditions of 30°C and 38°C that have a large response current, a trend is observed for the response current to vary in response to the Hct value. In particular, a conspicuous difference is observed in the region of 4 seconds or less under an applied voltage condition of 2.IV and the region of 3 seconds or more under an applied voltage condition of 2.2V when compared with an applied voltage of 2.15V.

0185Consequently, it is important to determine an optimal application voltage conditions with reference to the response current in the high-temperature region so that the response current is not dependent upon the Hct value under different temperature conditions. The optimal application voltage determined in the above manner in Working Example 7 is 2.15V. The current value after three seconds is 1.93 µA when the blood sample is introduced at a Hct value of 45% and a temperature of 21 ° C as shown in Table 2. <tables id="tabl0002" num="0002"><table frame="all"><title>Table 2</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="31mm" /><colspec colnum="2" colname="col2" colwidth="30mm" /><colspec colnum="3" colname="col3" colwidth="29mm" /><colspec colnum="4" colname="col4" colwidth="43mm" /><colspec colnum="5" colname="col5" colwidth="30mm" /><thead valign="top"><row><entry morerows="1" align="center" /><entry namest="col2" nameend="col3" align="center">Electrode Surface Area (mm²)</entry><entry morerows="1" align="center">Optimal Applied Voltage (V)</entry><entry morerows="1" align="center">Current Value (µA)</entry></row><row><entry align="center">Working Electrode</entry><entry align="center">Counter electrode</entry></row></thead><tbody><row><entry align="center">Working Example 7</entry><entry align="center">0.12</entry><entry align="center">0.48</entry><entry align="center">2.15</entry><entry align="center">1.93</entry></row><row><entry align="center">Working Example 8</entry><entry align="center">0.20</entry><entry align="center">0.40</entry><entry align="center">2,1</entry><entry align="center">1.69</entry></row><row><entry align="center">Working Example 9</entry><entry align="center">0.30</entry><entry align="center">0.30</entry><entry align="center">2.05</entry><entry align="center">1.48</entry></row></tbody></tgroup></table></tables>

[Working Example 8]

0186An electrode was formed so that the surface area of the portion 31 of the electrode 11 of the sensor chip is 0.20 mm2, and the surface area of the portion 32 of the electrode 12 of the sensor chip is 0.40 mm2. Other conditions are the same as the sensor chip described in Working Example 1. As described in Working Example 7, the optimal applied voltage m Working Example 8 determined with reference to the response current m the high temperature region is 2.1V. At this time, as illustrated in Table 2, the current value after three seconds is 1.69 µA when a blood sample with a Hct value of 45% and a temperature of 21 ° C is introduced.

[Working Example 9]

0187An electrode was formed so that the surface area of the portion 31 of the electrode 11 of the sensor chip is 0.30 mm2, and the surface area of the portion 32 of the electrode 12 of the sensor chip is 0.30 mm2. Other conditions are the same as the sensor chip described in Working Example 1.

0188As described in Working Example 7, the optimal applied voltage is determined with reference to the response current in the high temperature region. The optimal applied voltage in Working Example 9 is 2.05V. At this time, as illustrated in Table 2, the current value after three seconds is 1.48 µA when a blood sample with a Hct value of 45% and a temperature of 21 ° C is introduced. The results of Working Examples 7, 8 and 9 demonstrate that the dimension of the response current varied and the optimal applied current is different when the electrode surface area is different. Furthermore, under a condition in which the sum of the surface area of the working electrode is the same as that of the surface area of the counter electrode, a larger response current is obtained when the surface area of the counter electrode is large.

[Working Example 10]

0189A sensor chip is prepared as illustrated in <figref idref="f0002">FIG. 2</figref> and <figref idref="f0003">FIG. 3</figref>. The capillary is designed with a width of 1.2 mm, a length (depth) of 4.0 mm, and a height of 0.15 mm. The insulating plate is formed from polyethylene terephthalate, and palladium is deposited by vapor deposition onto the insulating plate. Thereafter, the respective electrodes are formed by formation of a slit in the palladium layer with a laser so that the surface area of the portion 31 of the electrode 11 is 0.30 mm2, and the portion 32 of the electrode 12 is 0.48 mm²

0190The reaction reagent layer is formed as follows. An aqueous solution including glucose dehydrogenase, potassium ferricyanide (Kanto Kagaku Co., Ltd.), taurine (Nakalai Tesque), glucose dehydrogenase was prepared. The concentration of glucose dehydrogenase is adjusted to a concentration of 2.0 U/sensor. A concentration of 1.7 mass% of potassium ferricyanide, and 1.0 mass% of taurine was dissolved in the aqueous solution to thereby obtain a reagent liquid. After coating of the reagent liquid onto the polyethylene terephthalate plate, drying is performed at a humidity of 45% and a temperature of 21° C.

0191The Hct value of the blood sample is 25%, 45% and 65%, and the glucose concentration is 40mg/dl, 80mg/dl, 200mg/dl, 400mg/dl, and 1,600mg/dl. The temperature of the blood sample was 4° C, I3° C, 22° C, 30° C, and 39° C.

0192The application voltage between the electrodes and the application time is set as follows. 2.075V was applied to both electrodes (temperature electrodes) being the electrode 11 (positive electrode ) and electrode 12 (negative electrode) for 3 seconds from immediately after introduction of the blood sample. From 3 seconds to five seconds, 0.25V was applied to both electrodes (analysis electrode) being the electrode 13 (positive electrode ) and electrode 14 (negative electrode), and at five seconds from introduction of the blood sample, the measurement is completed.

0193Table 3 and the graph illustrated in <figref idref="f0018">FIG. 18</figref> illustrate the response current value after three seconds between the temperature electrodes. The response current value after 3 seconds does not depend on the Hct value but rather depends on the temperature. The response current value after three seconds is converted to the temperature of the blood sample using the table illustrated in <figref idref="f0018">FIG. 18</figref>. A difference is not observed in the response current value after three seconds at different glucose concentrations. Table 4 below illustrates the response current value after 5 seconds between the analysis electrodes. The response current value after 5 seconds increases together with increases in the glucose concentration at each temperature, or increases together with increases in the temperature at each glucose concentration. When the temperature is known, the table illustrated in Table 4 below may be used as a conversion table for glucose concentration to thereby enable conversion of the response current value after 5 seconds to a glucose concentration for the blood sample. <tables id="tabl0003" num="0003"><table frame="all"><title>Table 3</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="55mm" /><colspec colnum="2" colname="col2" colwidth="31mm" /><colspec colnum="3" colname="col3" colwidth="13mm" /><colspec colnum="4" colname="col4" colwidth="13mm" /><colspec colnum="5" colname="col5" colwidth="13mm" /><thead valign="middle"><row><entry namest="col1" nameend="col2" morerows="1" align="center">Current value after 3 seconds (µA)</entry><entry namest="col3" nameend="col5" align="center">Hematocrit</entry></row><row><entry align="center">25%</entry><entry align="center">45%</entry><entry align="center">65%</entry></row></thead><tbody valign="middle"><row><entry morerows="4" align="center">Blood Temperature</entry><entry align="center">4°C</entry><entry align="center">0.83</entry><entry align="center">0.82</entry><entry align="center">0.83</entry></row><row><entry align="center">13°C</entry><entry align="center">1.16</entry><entry align="center">1,19</entry><entry align="center">1.22</entry></row><row><entry align="center">22°C</entry><entry align="center">1.66</entry><entry align="center">1.63</entry><entry align="center">1.64</entry></row><row><entry align="center">30°C</entry><entry align="center">2.13</entry><entry align="center">2.12</entry><entry align="center">2.16</entry></row><row><entry align="center">39°C</entry><entry align="center">2.76</entry><entry align="center">2.81</entry><entry align="center">2.80</entry></row></tbody></tgroup></table></tables><tables id="tabl0004" num="0004"><table frame="all"><title>Table 4</title><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="55mm" /><colspec colnum="2" colname="col2" colwidth="31mm" /><colspec colnum="3" colname="col3" colwidth="15mm" /><colspec colnum="4" colname="col4" colwidth="15mm" /><colspec colnum="5" colname="col5" colwidth="15mm" /><colspec colnum="6" colname="col6" colwidth="15mm" /><colspec colnum="7" colname="col7" colwidth="15mm" /><thead valign="middle"><row><entry namest="col1" nameend="col2" morerows="1" align="center">Current value after 5 seconds (µA)</entry><entry namest="col3" nameend="col7" align="center">Glucose Concentration (mg/dl)</entry></row><row><entry align="center">40</entry><entry align="center">80</entry><entry align="center">200</entry><entry align="center">400</entry><entry align="center">600</entry></row></thead><tbody valign="middle"><row><entry morerows="4" align="center">Blood Temperature</entry><entry align="center">4°C</entry><entry align="center">1.46</entry><entry align="center">2.35</entry><entry align="center">4.52</entry><entry align="center">6.85</entry><entry align="center">8.31</entry></row><row><entry align="center">13°C</entry><entry align="center">1.75</entry><entry align="center">2.85</entry><entry align="center">5.60</entry><entry align="center">9.22</entry><entry align="center">11.89</entry></row><row><entry align="center">22°C</entry><entry align="center">2.15</entry><entry align="center">3.56</entry><entry align="center">6.89</entry><entry align="center">12.03</entry><entry align="center">15.81</entry></row><row><entry align="center">30°C</entry><entry align="center">2.48</entry><entry align="center">4.35</entry><entry align="center">8.44</entry><entry align="center">14.82</entry><entry align="center">20.20</entry></row><row><entry align="center">39°C</entry><entry align="center">2.93</entry><entry align="center">4.96</entry><entry align="center">10.50</entry><entry align="center">17.81</entry><entry align="center">23.85</entry></row></tbody></tgroup></table></tables>

[Working Example 11]

0194Four types of sensor chips having the configuration illustrated in <figref idref="f0009">FIG. 9</figref> and <figref idref="f0010">FIG. 10</figref> were prepared. In the first to the four types of sensor chips, the interelectrode distance illustrated in <figref idref="f0019">FIG. 19</figref> is respectively 100 µm, 300 µm, 500 µm, and 700 µm.

0195Nine types of blood samples being combinations of three Hct values respectively of 25%, 45% and 65% and three temperatures of 11° C, 21 ° C, and 30° C were prepared.

0196Next, after introduction of the blood samples above into the capillary in the sensor chips above, a 2.2V voltage was applied between the electrodes 15 (temperature electrodes), and the respective response currents were measured.

0197The measurement results are illustrated in the graphs in <figref idref="f0020">FIGs 20(a) - 20(d)</figref>, <figref idref="f0021">FIGs 21(a) - 21(d)</figref>, and <figref idref="f0022">FIGs 22(a) - 22(d)</figref>. <figref idref="f0020">FIGs 20(a) - 20(d)</figref> illustrate the response current value in an 11° C blood sample by inter-electrode distance and by hematocrit. <figref idref="f0021">FIGs. 21(a) - 21(d)</figref> illustrate the response current value in a 21° C blood sample by inter-electrode distance and by hematocrit. <figref idref="f0022">FIGs. 22(a) - 22(d)</figref> illustrate the response current value in a 30°C blood sample by interelectrode distance and by hematocrit.

0198The graphs above do not exhibit a significant difference in the response current value when the interelectrode distance is varied. The results of Working Example 11 demonstrate that the response current exhibits almost no effect due to the inter-electrode distance.

[Working Example 12]

0199Two types of sensor chips having different electrode shapes were prepared.

0200A first type of sensor chip has the configuration illustrated in <figref idref="f0009">FIG. 9</figref>, <figref idref="f0010">FIG. 10</figref> and <figref idref="f0023">FIG. 23(a)</figref>. In the first type of sensor chip, the surface area of the portion 31 (working electrode) of the electrode 11 is 0.24 mm2, and the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.96 mm2, and the inter-electrode distance is 300 µm.

0201A second type of sensor chip has the configuration illustrated in <figref idref="f0023">FIG. 23(b)</figref>. In the second type of sensor chip, the surface area of the portion 31 (working electrode) of the electrode 11 is 0.24 mm2, and the portion 32 (counter electrode) of the electrode 12 has a shape that is formed separately at two positions in <figref idref="f0023">FIG. 23(b)</figref>. The surface area of the two portions of the portion 32 are respectively 0.48 mm2. The total value for the portion 32 of the electrode 12 is 0.96 mm2. In the second type of sensor chip, the inter-electrode distance is 300 µm.

0202Nine types of blood samples being combinations of three Hct values respectively of 25%, 45% and 65% and three temperatures of 11° C, 21 ° C, and 30°C were prepared.

0203Next, after introduction of the blood samples above into the capillary in the sensor chips above, a 2.2V voltage was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0204The measurement results are illustrated in the graphs in <figref idref="f0024">FIGs. 24(a)-24(b)</figref>, <figref idref="f0025">FIGs. 25(a)-25(b)</figref>, and <figref idref="f0026">FIGs. 26(a)- 26(b)</figref>. <figref idref="f0024">FIGs.24(a)-24(b)</figref> illustrate the response current value in an 11° C blood sample by electrode shape and by hematocrit. <figref idref="f0025">FIGs. 25(a)- 25(b)</figref> illustrate the response current value in a 21 ° C blood sample by electrode shape and by hematocrit. <figref idref="f0026">FIGs. 26(a)-26(b)</figref> illustrate the response current value in a 30° C blood sample by electrode shape and by hematocrit.

0205The graphs above do not exhibit a significant difference in the response current value when the electrode shape distance is varied. The results of Working Example 12 demonstrate that the response current exhibits almost no effect due to the electrode shape.

[Working Example 13]

0206Four types of sensor chips having different lead widths in the counter electrode 12 were prepared. The respective types of sensor chip have the configuration illustrated in <figref idref="f0002">FIG. 2</figref>, <figref idref="f0003">FIG. 3</figref> and <figref idref="f0027">FIG. 27(a)</figref>. In each type of sensor chip, the surface area of the portion 31 (working electrode) of the electrode 11 is 0.30 mm2, and the portion 32 (counter electrode) of the electrode 12 is 0.30 mm2, and the inter-electrode distance is 100 µm. In the first to the fourth types of sensor chip, the lead width in the counter electrode 12 illustrated in <figref idref="f0027">FIG. 27(b)</figref> is respectively 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm.

0207Three types of blood samples were prepared. The Hct values for a first to a third type of blood sample are respectively 25%, 45% and 65% and a temperature for each type of blood sample is 23° C (room temperature).

0208Next, after introduction of the blood samples above into the capillary in the sensor chips above, a 2.05V voltage was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0209The measurement results are illustrated in the graphs in <figref idref="f0028">FIGs 28(a)</figref>·28(d). These graphs demonstrate that the response current exhibits almost no change even at different hematocrit values. Furthermore, a significant difference is not observed in the response current value when the lead width is varied. The results of Working Example 13 demonstrate that the response current exhibits almost no effect due to the lead width (resistance).

[Working Example 14]

0210Two types of sensor chips were prepared. A first and a second type of sensor chip have the configuration illustrated in <figref idref="f0009">FIG. 9</figref> and <figref idref="f0010">FIG. 10</figref>. In the first and the second type of sensor chip, the surface area of the portion 31 (working electrode) of the electrode 11 is 0.12 mm2, and the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.48 mm 2,and the inter-electrode distance is 300 µm. In the first type and the second type of sensor chip, the thickness of the spacer 202 illustrated in <figref idref="f0029">FIG. 29</figref> (capillary height) is respectively 0.15 mm and 0.09 mm.

0211Nine types of blood samples being combinations of three Hct values respectively of 25%, 45% and 65% and three temperatures of 11° C, 21 ° C, and 30°C were prepared.

0212Next, after introduction of the blood samples above into the capillary in the sensor chips above, a 2.2V voltage was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0213The measurement results are illustrated in the graphs in <figref idref="f0030">FIGs. 30(a) - 30(b)</figref>, <figref idref="f0031">FIGs. 31(a) - 31(b)</figref>, and <figref idref="f0032">FIGs. 32(a) - 32(b)</figref>. <figref idref="f0030">FIGs. 30(a) - 30(b)</figref> illustrate the response current value in an 11° C blood sample by capillary height and by hematocrit. <figref idref="f0031">FIGs. 31(a) - 31(b)</figref> illustrate the response current value in a 21 ° C blood sample by capillary height and by hematocrit. <figref idref="f0032">FIGs. 32(a) - 32(b)</figref> illustrate the response current value in a 30° C blood sample by capillary height 10 and by hematocrit.

0214The graphs above do not exhibit a significant difference in the response current value even when the capillary height is varied. The results of Working Example 14 demonstrate that the response current exhibits almost no effect due to the capillary height.

[Working Example 15]

0215Two types of sensor chips were prepared. The respective types of sensor chip have the configuration illustrated in <figref idref="f0009">FIG. 9</figref> and <figref idref="f0010">FIG. 10</figref>. In each type of sensor chip, the surface area of the portion 31 (working electrode) of the electrode 11 is 0.12 mm2, and the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.48 mm2, and the Inter-electrode distance is 100 µm. The surface resistance of the palladium vapor-deposited plate of the first type and the second type of sensor chip is respectively 115 Q/o and 60 Q/o.

0216Fifteen types of blood samples being combinations of three Hct values respectively of 25%, 45% and 65% and the temperatures of 4° C, 13° C, 21 ° C, 30 ° C, and 38° C were prepared.

0217Next, after introduction of the above blood samples above into the above capillary in the sensor chips, a 2.15V voltage was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0218The measurement results are illustrated in the graphs in figures (a) and (b) in <figref idref="f0033 f0034 f0035 f0036 f0037">FIGs. 33 - 37</figref>. <figref idref="f0033">FIG. 33(a) and 33(b)</figref> illustrate the response current value in a 4 ° C blood sample by palladium resistance. <figref idref="f0034">FIG. 34(a) and 34(b)</figref> illustrate the response current value in a 13° C blood sample by palladium resistance. <figref idref="f0035">FIG. 35(a) and 35(b)</figref> illustrate the response current value in a 21 ° C blood sample by palladium resistance. <figref idref="f0036">FIG. 36(a) and 36(b)</figref> illustrate the response current value in a 30° C blood sample by palladium resistance. <figref idref="f0037">FIG. 37(a) and 37(b)</figref> illustrate the response current value in a 38°C blood sample by palladium resistance.

0219The graphs above do not exhibit a significant difference in the response current value when palladium resistance is varied. The results of Working Example 15 demonstrate that the response current exhibits almost no effect due to the palladium resistance. There is no necessity to explain that when a known conductive material such as platinum, gold, silver, titanium, copper, nickel, and carbon is applied to the plate, the same effect is obtained.

[Working Example 16]

0220Sensor chips were prepared to have the configuration illustrated in <figref idref="f0009">FIG. 9</figref> and <figref idref="f0010">FIG. 10</figref>. In the sensor chips, the surface area of the portion 31 (working electrode) of the electrode 11 is 0.12 mm2, the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.48 mm 2, and the inter-electrode distance is 100 µm.

0221Three types of blood samples were prepared by adding a glucose concentrate to blood having a Hct value of 45% and a temperature of 24°C. The glucose concentrations of the first to the third blood sample are respectively 0mg/dL, 205 mg/dL, and 640 mg/dL.

0222Next, the above blood samples were introduced into the capillaries of the respective sensor chips above. Thereafter, a voltage of 2.15V was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0223The measurement results are illustrated in the graph in <figref idref="f0038">FIG 38. FIG. 38</figref> illustrates the response current value in a 24 ° C blood sample by glucose concentration. The graphs above do not exhibit a significant difference in the response current value when glucose concentration is varied. The results of Working Example 16 demonstrate that the response current exhibits almost no effect due to glucose concentration. When this Working example is applied to a blood glucose sensor (glucose sensor), since the measurements are not affected by the glucose concentration, it is shown that application is possible without problems.

[Working Example 17]

0224Sensor chips were prepared as in <figref idref="f0009">FIG. 9</figref> and <figref idref="f0010">FIG. 10</figref> so that the surface area of the portion 31 (working electrode) of the electrode 11 is 0.12 mm2 , the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.48 mm2, and the inter-electrode distance is 100 µm.

0225(0210] Three types of blood samples with different ascorbic acid concentrations were prepared by adding an ascorbic acid concentrate to blood having a Hct value of 45% and a temperature of 24°C. The glucose concentrations of the first to the third blood sample are respectively 0 mg/dL, 10 mg/dL, and 20 mg/dL.

0226Next, the above blood samples were introduced into the capillaries of the respective sensor chips above. Thereafter, a voltage of 2.15V was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0227The measurement results are illustrated in the graph in <figref idref="f0039">FIG 39. FIG. 39</figref> illustrates the response current value in a 24° C blood sample by ascorbic acid concentration. The graphs above do not exhibit a significant difference in the response current value when ascorbic acid concentration is varied. That is to say, in the present working example, the measurement accuracy for blood glucose level waR not affected by the Rerum concentration of ascorbic acid , that is a reducing substance. Therefore it is shown that the sensor chip according to the present working example can be used without problems as a blood glucose level sensor.

[Working Example 18]

0228Sensor chips were prepared to have the configuration illustrated in <figref idref="f0009">FIG. 9</figref> and <figref idref="f0010">FIG. 10</figref>. In the sensor chips, the surface area of the portion 31 (working electrode) of the electrode 11 is 0.12 mm2, the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.48 mm2, and the inter-electrode distance is 100 µm.

0229Two types of blood samples having different temperatures were prepared. A first type of blood sample has a Hct value of 45% and a temperature of 4 °C. A second type of blood sample has a Hct value of 45% and a temperature of 42° C.

0230Next, one minute after moving the above blood samples to a 24°C environment, the samples were introduced into the capillaries of the respective sensor chips described above. Thereafter, a voltage of 2.15V was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0231The measurement results are illustrated in the graph in <figref idref="f0040">FIG 40</figref>. The dotted line in <figref idref="f0040">FIG. 40</figref> illustrates the response current value when introducing blood at 24°C to a 24°C environment (hereinafter referred to as "normal introduction"). The solid line in <figref idref="f0040">FIG. 40</figref> illustrates the response current value when introducing blood at 4°C to a 24 ° C environment (hereinafter referred to as "4° C introduction"). The broken line in <figref idref="f0040">FIG. 40</figref> illustrates the response current value when introducing blood at 42 ° C to a 24 ° C environment (hereinafter referred to as "42° C introduction").

0232The graphs illustrate that during a time period soon after the measurement period, the temperature exhibited by the 4 ° C introduction is low in comparison to the temperature exhibited by the normal introduction, and the temperature exhibited by the 42°C introduction is high in comparison to the temperature exhibited by the normal introduction. Over the passage of time during the measurement period, the temperature difference between the 42° C introduction and the 4°C introduction disappears. The fact that the temperature difference disappears due to the passage of the measurement period is thought in both cases to result from the movement of the blood sample at 4°C or 42°C to a 24°C environment, and therefore over the passage of time, both samples shift to 24°C that is the temperature of the sensor chip.

0233According to Working Example 18, it is shown that measurement of temporal variation in relation to the temperature of the blood sample is possible.

0234Furthermore, the sensor chip is provided with a temperature electrode that is disposed to make contact with the blood sample, and measures the temperature of the blood sample. Therefore, when the sensor chip is used, a temperature for the blood sample that takes into consideration temporal variation can be obtained, and this value can be used to correct the glucose concentration and the like. In other words, the accuracy of various types of corrections can be improved.

[Working Example 19]

0235Sensor chips were prepared to have the configuration illustrated in <figref idref="f0009">FIG. 9</figref> and <figref idref="f0010">FIG. 10</figref>. In the sensor chips, the surface area of the portion 31 (working electrode) of the electrode 11 is 0.12 mm2, the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.48 mm2, and the inter-electrode distance is 100 µm.

0236A blood sample was prepared. The blood sample has a Hct value of 45%. As illustrated in <figref idref="f0041">FIG. 41</figref>, approximately 3 µL of blood was dripped in advance into the sensor chip.

0237The blood was dripped onto an upper portion of the cover 203. Dripping blood in this manner is hereinafter referred to as "upward orientation".

0238Approximately 10 µL of blood was dripped in advance into the other sensor chip. The blood was dripped onto a lower portion of the insulating plate 201. Dripping blood in this manner is hereinafter referred to as "downward orientation".

0239Next, the above blood samples were introduced in a 24°C environment into the capillaries 204 of the respective sensor chips. Thereafter, a voltage of 2.15V was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0240The measurement results are illustrated in the graph in <figref idref="f0042">FIG 42</figref>. The broken line in <figref idref="f0042">FIG. 42</figref> illustrates the response current when dripping blood in advance in an upward orientation in a 24 ° C environment. The solid line in <figref idref="f0042">FIG. 42</figref> illustrates the response current when dripping blood in advance in a downward orientation in a 24 ° C environment. The dotted line m <figref idref="f0042">FIG. 42</figref> illustrates the response current when dripping blood in advance in both an upward orientation and a downward orientation in a 24°C environment (hereinafter referred to as "normal introduction").

0241The graphs illustrate that in comparison to normal introduction, the response current value is low during an upward orientation and during a downward orientation. This is thought to be due to the fact that the temperature of the blood sample in the capillary 204 is reduced by the heat of evaporation of blood in an upward orientation and during a downward orientation that becomes excessively attached to an outer range of the capillary 204.

0242Working Example 19 enables comprehension of the effect of heat of evaporation as illustrated in <figref idref="f0042">FIG. 42</figref>.

0243The sensor chip is provided with a temperature electrode that is disposed to make contact with the blood sample, and that measures the temperature of the blood sample. Therefore, a temperature for the blood sample that takes into consideration heat of evaporation can be obtained, and this value can be used to correct the glucose concentration and the like. In other words, the accuracy of various types of corrections can be improved.

[Working Example 20]

0244Sensor chips were prepared to have the configuration illustrated in <figref idref="f0005">FIG. 5</figref><figref idref="f0009">9</figref> and <figref idref="f0010">FIG. 10</figref> in that the surface area of the portion 31 (working electrode) of the electrode 11 is 0.12 mm2, the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.48 mm2, and the inter-electrode distance is 100 µm. A blood sample with a Hct value of 45% was prepared.

0245Immediately after the distal end of the sensor chip gripped in the fingers for 5 seconds is mounted onto the measuring device, and immediately after the distal end of the sensor chip not gripped in the fingers is mounted onto the measuring device, the blood sample above is introduced in a 24° C environment. Thereafter, a voltage of 2.15V was applied between the electrodes (temperature electrodes), and the respective response currents were measured.

0246The measurement results are illustrated in the graph in <figref idref="f0043">FIG 43</figref>. The solid line in <figref idref="f0043">FIG. 43</figref> illustrates the response current when the distal end of the sensor chip is gripped in the fingers for 5 seconds in a 24°C environment. The solid line in <figref idref="f0043">FIG. 43</figref> illustrates the response current when the distal end of the sensor chip is not gripped in the fingers for 5 seconds in a 24° C environment (hereinafter referred to as normal introduction").

0247According to Working Example 20, an error in the finger tip temperature as illustrated in <figref idref="f0043">FIG. 43</figref> can be comprehended.

0248The sensor chip used in the present invention is provided with a temperature electrode that is disposed to make contact with the blood sample, and that measures the temperature of the blood sample. Therefore, a temperature for the blood sample that takes into consideration finger-tip temperature can be obtained, and this value can be used to correct the glucose concentration and the like. In other words, the accuracy of various types of corrections can be improved.

[Working Example 21]

0249Sensor chips as described in Working Example 10 were prepared as illustrated in <figref idref="f0002">FIG. 2</figref> and <figref idref="f0003">FIG. 3</figref> in that the surface area of the portion 31 (working electrode) of the electrode 11 is 0.30 mm2, the surface area of the portion 32 (counter electrode) of the electrode 12 of the sensor chip is 0.48 mm2, and the inter-electrode distance is 100 µm. Blood samples with a glucose concentration of 209 mg/dL, Hct values of 25%, 45%, and 65% were prepared at a temperature of 22° C.

0250Next, after introduction of the blood samples into the capillary of the sensor chips as described above, a predetermined voltage was applied between predetermined electrodes in the order illustrated in <figref idref="f0044">FIG. 44</figref>. In other words, from 0 seconds to 3.0 seconds, a voltage of 2075 mV is applied to electrode 11 and electrode 12 (electrodes 11-12 in <figref idref="f0044">FIG. 44</figref>). Then from 3.0 seconds to 5.0 seconds, a voltage of 250 mV is applied to electrode 13 and electrode 14 (electrodes 13-14 in <figref idref="f0044">FIG. 44</figref>). Then from 5.1 seconds to 5.5 seconds, a voltage of 2500 mV is applied to electrode 11 and electrode 13 (electrodes 11-13 in <figref idref="f0044">FIG. 44</figref>). The respective response currents were measured.

0251The measurement results are illustrated by the graph in <figref idref="f0045">FIG. 45(a) and FIG. 45(b)</figref>. These graphs illustrate that a response current value according to the hematocrit value can be obtained when using glucose or Hct (hematocrit) as a measurement target. Furthermore as illustrated in <figref idref="f0046">FIG. 46(a)</figref>, a response current value can be obtained in relation to a predetermined temperature as illustrated in <figref idref="f0046">FIG. 46(b)</figref> in relation to temperature.

0252According to Working Example 21, it is shown that measurement in sequence is possible in relation to respective features such as glucose, temperature or Hct.

0253The measurement sequence of glucose, temperature and Hct is not fixed to the sequence above, and may be executed in an arbitrary sequence. For example, the sequence of temperature, Hct and glucose is possible.

0254As illustrated in <figref idref="f0047">FIG. 47</figref>, measurement is possible in relation to features including glucose, temperature, Hct and a reducing substance. In other words, as illustrated in <figref idref="f0047">FIG. 47</figref>, a voltage may be applied from 0 seconds to 3.0 seconds to electrode 11 and electrode 12 (electrodes 11-12 in <figref idref="f0047">FIG. 47</figref>), from 3.0 seconds to 4.95 seconds to electrode 12 and electrode 14 (electrodes 12-14 in <figref idref="f0047">FIG. 47</figref>), then substantially at the same time, from (3 seconds to 5.0 seconds), to electrode 13 and electrode 14 (electrodes 13-14 in <figref idref="f0047">FIG. 47</figref>), and from 5.1 seconds to 5.5 seconds to electrode 11 and electrode 13 (electrodes 11-13 in <figref idref="f0047">FIG. 47</figref>). This configuration also obtains a response current that corresponds to the respective conditions.

0255When measuring two or more features at the same time, care is required to avoid mixing combinations of the working electrode and the counter electrode. For example, when measuring glucose at the same time as temperature, it is preferred to measure the response current of the glucose measurement with electrode 13 and electrode 14 (electrodes 13 - 14 in <figref idref="f0047">FIG. 47</figref>), and the response current of the temperature measurement with electrode 11 and electrode 12 (electrodes 11 - 12 in <figref idref="f0047">FIG. 47</figref>). When the glucose response current flows between electrodes 13 - 12 or the temperature response current flows between electrodes 11- 14, the desired response current cannot be obtained. As a result, when measuring two or more features at the same time, it is important to select suitable combinations of electrodes for application of voltage, suitable application voltage and application time in order to avoid the mixing as described above.

[Modified Example 1]

0256As illustrated in <figref idref="f0006">FIG. 6(a)</figref>, the step of determining the analyte concentration in the blood sample in step 84 (concentration determination step) was explained with reference to an example including step 8101 to step 8106.

0257For example, as illustrated m <figref idref="f0048">FIG. 48(a)</figref>, the concentration determination step 84 may include a step 141 for correcting the data b based on the data a. The computing unit (concentration determination unit) 306 in the biosensor system 100 (refer to <figref idref="f0004">FIG. 4</figref>) includes a first analyte correcting unit 321 configured to correct the data b based on the data a as illustrated in FIG. 50Ca).

0258Furthermore, as illustrated m <figref idref="f0048">FIG. 48(b)</figref>, the concentration determination step 84 may include a step 8241 for calculating of the concentration x of the analyte in the blood sample based on the data b and a step 8242 for correcting the concentration x based on the data a. The computing unit (concentration determination unit) 306 in the biosensor system 100 (refer to <figref idref="f0004">FIG. 4</figref>) includes a concentration calculating unit 331 configured to calculate a concentration x of an analyte in the blood sample based on data b, and a second analyte correcting unit 332 configured to correct a concentration x based on the data a as illustrated in <figref idref="f0050">FIG. 50(b)</figref>.

0259As illustrated in <figref idref="f0049">FIG. 49(a)</figref>, the concentration determination step 84 may include a step S341 for calculating the temperature t of the blood sample based on the data a, and a step S342 for correcting the data b based on the temperature t. The computing unit (concentration determination unit) 306 in the biosensor system 100 (refer to <figref idref="f0004">FIG. 4</figref>) includes a temperature calculating unit 341 configured to calculate a temperature t of the blood sample based on data a, and a third analyte correcting unit 342 configured to correct the data b based on the temperature t as illustrated in <figref idref="f0051">FIG. 51(a)</figref>.

0260As illustrated in <figref idref="f0049">FIG. 49(b)</figref>, the concentration determination step S4 may include a step S441 for calculating the temperature t of the blood sample based on the data a, and a step S442 for calculating the concentration x of the analyte in the blood sample based on the data b. The computing unit (concentration determination unit) 306 in the biosensor system 100 (refer to <figref idref="f0004">FIG. 4</figref>) includes a temperature calculating unit 351 configured to calculate a temperature t of the blood sample based on data a, a concentration calculating unit 352 configured to calculate a concentration x of the analyte in the blood sample based on the data b, and a fourth analyte correcting unit 353 configured to correct the concentration x based on the temperature t as illustrated in <figref idref="f0051">FIG. 51(b)</figref>.

[Modified Example 2]

0261The control circuit 300 in the above embodiment as illustrated in <figref idref="f0052">FIG. 52</figref> may be further provided with a sequence control unit 501 and an electrode selection unit 502.

0262The sequence control unit 501 may control the control circuit 300 to simultaneously measure at least two features when measuring temperature, glucose, hematocrit, or a reducing substance. Furthermore the sequence control unit 501 may control the control circuit 300 to perform independent measurements when measuring temperature, glucose, hematocrit, or a reducing substance. The sequence of measuring these respective features is arbitrary. The sequence control unit 501 may control the control circuit 300 to perform independent measurements in the sequence of temperature, glucose and a reducing substance, and hematocrit when measuring temperature, glucose, hematocrit, or a reducing substance.

0263The electrode selection unit 502 may control the control circuit 300 to perform measurements through independent electrodes when measuring temperature, glucose, hematocrit, or a reducing substance.

INDUSTRIAL APPLICABILITY

0264During measurement of glucose in a blood sample, the present invention enables suppressing the measurement error caused by temperature when executing measurements, and therefore has useful value in broad technical areas that require high measurement accuracy. <tables id="tabl0005" num="0005"><table frame="none"><title>REFERENCE NUMBERS</title><tgroup cols="4" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="74mm" /><colspec colnum="3" colname="col3" colwidth="24mm" /><colspec colnum="4" colname="col4" colwidth="29mm" /><tbody><row><entry>11, 12,13, 14, 15</entry><entry namest="col2" nameend="col4" align="left">ELECTRODE (VOLTAGE APPLICATION PORTION)</entry></row><row><entry>16</entry><entry>DISCHARGE PORT</entry><entry /><entry /></row><row><entry>17</entry><entry namest="col2" nameend="col4" align="left">BLOOD SAMPLE INTRODUCTION PORT</entry></row><row><entry>20</entry><entry>REACTION REAGENT LAYER</entry><entry /><entry /></row><row><entry>31</entry><entry>PORTION OF ELECTRODE</entry><entry>11</entry><entry>FACING CAPILLARY</entry></row><row><entry>32</entry><entry>PORTION OF ELECTRODE</entry><entry>12</entry><entry>FACING CAPILLARY</entry></row><row><entry>33</entry><entry>PORTION OF ELECTRODE</entry><entry>13</entry><entry>FACING CAPILLARY</entry></row><row><entry>34</entry><entry>PORTION OF ELECTRODE</entry><entry>14</entry><entry>FACING CAPILLARY</entry></row><row><entry>35</entry><entry>PORTION OF ELECTRODE</entry><entry>15</entry><entry>FACING CAPILLARY</entry></row><row><entry>40</entry><entry>CAPILLARY</entry><entry /><entry /></row><row><entry>41</entry><entry namest="col2" nameend="col4" align="left">MEASURING UNIT A (TEMPERATURE MEASURING UNIT)</entry></row><row><entry>42</entry><entry namest="col2" nameend="col4" align="left">MEASURING UNIT B (ANALYTE MEASURING UNIT)</entry></row><row><entry>100</entry><entry>BIOSENSOR SYSTEM</entry><entry /><entry /></row><row><entry>101</entry><entry>MEASURING DEVICE</entry><entry /><entry /></row><row><entry>102</entry><entry>MOUNTING PORT</entry><entry /><entry /></row><row><entry>103</entry><entry>DISPLAY UNIT</entry><entry /><entry /></row><row><entry>200</entry><entry>SENSOR CHIP</entry><entry /><entry /></row><row><entry>201</entry><entry>INSULATING PLATE</entry><entry /><entry /></row><row><entry>202</entry><entry>SPACER</entry><entry /><entry /></row><row><entry>203</entry><entry>COVER</entry><entry /><entry /></row><row><entry>204</entry><entry>NOTCH</entry><entry /><entry /></row><row><entry>210</entry><entry>SENSOR CHIP</entry><entry /><entry /></row><row><entry>300</entry><entry>CONTROL CIRCUIT</entry><entry /><entry /></row><row><entry>301a, 301b, 301c, 301d, 301e</entry><entry>CONNECTOR</entry><entry /><entry /></row><row><entry>302</entry><entry>SWITCHING CIRCUIT</entry><entry /><entry /></row><row><entry>303</entry><entry>CURRENTNOLTAGE CONVERSION CIRCUIT</entry><entry /><entry /></row><row><entry>304</entry><entry>ANALOG/DIGITAL (AID) CONVERSION CIRCUIT</entry><entry /><entry /></row><row><entry>305</entry><entry>REFERENCE VOLTAGE POWER SOURCE</entry><entry /><entry /></row><row><entry>306</entry><entry>COMPUTING UNIT (CONCENTRATION DETERMINATION UNIT)</entry><entry /><entry /></row><row><entry>307</entry><entry>TEMPERATURE MEASURING UNIT</entry><entry /><entry /></row><row><entry>308</entry><entry>COMPUTING UNIT</entry><entry /><entry /></row><row><entry>309</entry><entry>CONCENTRATION CALCULATING UNIT</entry><entry /><entry /></row><row><entry>310</entry><entry>TEMPERATURE CALCULATING UNIT</entry><entry /><entry /></row><row><entry>311</entry><entry>CONCENTRATION CALCULATING UNIT</entry><entry /><entry /></row><row><entry>312</entry><entry>ENVIRONMENTAL TEMPERATURE MEASURING UNIT</entry><entry /><entry /></row><row><entry>313</entry><entry>COMPARISON UNIT</entry><entry /><entry /></row><row><entry>314</entry><entry>CORRECTION UNIT</entry><entry /><entry /></row><row><entry>315</entry><entry>ENVIRONMENTAL TEMPERATURE MEASURING UNIT</entry><entry /><entry /></row><row><entry>321</entry><entry>FIRST ANALYTE CORRECTIO N UNIT</entry><entry /><entry /></row><row><entry>331</entry><entry>CONCENTRATION CALCULATING UNIT</entry><entry /><entry /></row><row><entry>332</entry><entry>SECOND ANALYTE CORRECTIO N UNIT</entry><entry /><entry /></row><row><entry>341</entry><entry>TEMPERATURE CALCULATING UNIT</entry><entry /><entry /></row><row><entry>342</entry><entry>THIRD ANALYTE CORRECTION UNIT</entry><entry /><entry /></row><row><entry>351</entry><entry>TEMPERATURE CALCULATING UNIT</entry><entry /><entry /></row><row><entry>352</entry><entry>CONCENTRATIO N CALCULATING UNIT</entry><entry /><entry /></row><row><entry>353</entry><entry>FOURTH ANALYTE CORRECTION UNIT</entry><entry /><entry /></row><row><entry>400</entry><entry>DISPLAY UNIT</entry><entry /><entry /></row><row><entry>501</entry><entry>SEQUENCE CONTROL UNIT</entry><entry /><entry /></row><row><entry>502</entry><entry>ELECTRODE SELECTION UNIT</entry><entry /><entry /></row><row><entry>S</entry><entry>STEP</entry><entry /><entry /></row></tbody></tgroup></table></tables>