Read-write assay system

TECHNICAL FIELD

0001The present invention relates generally to medical testing, and more particularly to lateral flow assay.

BACKGROUND ART

0002In patient care, immunoassay technology provides simple and relatively quick means for determining the presence of analytes in a subject sample. Analytes are substances of interest or clinical significance that may be present in biological or non-biological fluids. The analytes can include antibodies, antigens, drugs, or hormones.

0003The analyte of interest is generally detected by reaction with a capture agent, which yields a device more easily detected and measured than the original analyte. Detection methods can include a change in absorbance, particularly a change in color, change in fluorescence, change in luminescence, change in electrical potential at a surface, change in other optical properties, or any other easily measured physical property indicating the presence or absence of an analyte in a sample.

0004New immunoassay devices have been developed that play an important role in areas such as clinical chemistry. They are used by skilled clinicians and laypersons alike. Thus, there is a strong impetus to provide devices that are simple and reliable. Desirably, the assays are single-step devices wherein the user need only apply the sample prior to viewing the result. Single-step devices obviate the necessity of performing complicated and time consuming processing steps that may introduce errors in the end result.

0005Immunoassay tests are often critical to patient care. Assays are routinely performed to detect the presence of particular analytes that are present when a human or non-human subject has a particular disease or condition, such as HIV, flu, alcohol, drugs, ovulation, pregnancy, etc.

0006Immunoassay technology now allows for assay tests to be performed without the complex and expensive equipment used in hospitals and laboratory settings. Kits for performing assays are now available for home or point of care use to quickly determine the presence of a disease or condition by providing qualitative results for the analyte or tested condition. These kits generally include strips that provide a visual indication when the analyte being sought is detected.

0007Generally, these assays have an extended base layer on which a differentiation can be made between a sample application region and an evaluation region. In typical use, the sample is applied to the sample application region, flows along a liquid transport path, which runs parallel to the base layer, and then flows into the evaluation region. A capture reagent is present in the evaluation region, and the captured analyte can be detected by a variety of protocols to detect visible moieties as described above associated with the captured analyte.

0008The above assays are called lateral flow assays or immunoassays and are currently single use and disposable.

0009<patcit id="pcit0001" dnum="US20020146699A1"><text>US 2002/0146699 A1</text></patcit> relates to a method and apparatus for improving the performance of microanalytic and microsynthetic procedures and discloses a micro-system platform comprising a disk which is divided into two bands, namely an information/data band and an analytical band wherein the bands are formed utilizing standard compact disc technology. Information stored in the band may relate to operating instructions necessary to perform the test associated with the assay.

0010<patcit id="pcit0002" dnum="EP1048723A1"><text>EP 1 048 723 A1</text></patcit> relates to a biochip and a method of using a biochip. In order to provide a biochip whose information can unitarily be managed, a memory is integrated into a biochip so as to store information such as types, amounts and spotting locations of spotted DNA's. A biochip of this kind allows the entire information of the biochip (e.g. what kind of DNA's are spotted on which locations of the biochip, and when, by whom and in what kind of experiment the biochip was used, data of experimental environment used for the biochip) to unitarily be managed.

0011<patcit id="pcit0003" dnum="EP1396725A1"><text>EP 1 396 725 A1</text></patcit> relates to a system and method for detecting biological and chemical material. A measurement kit is provided which comprises a measurement apparatus, a sensor mounted on the measurement apparatus, and a receiving mechanism mounted on the measurement apparatus for receiving information supplied externally. In particular, an external control unit sends an identification number for identifying a specific measurement apparatus among plural measurement apparatus by device of an electromagnetic wave, a change in the magnetic field, or a change in the electric field. The identification number is transmitted to the plural measurement apparatus in the sample vessel, received by the antenna mounted on each measurement apparatus, and after passing through the rectifying and demodulating circuits, and matched against the measurement apparatus-specific identification number pre-written in the measurement apparatus. Matching is performed in the matching circuit in the control circuit block of each measurement apparatus. When the identification number sent from the external control unit is matched against the pre-written identification number and match is established between them, the measured signals are transmitted from the measurement apparatus, in which match is achieved, through a communication control/signal processing circuit block and modulation circuit block via the antenna to the external control unit by device of an electromagnetic wave, a change in the magnetic field, or a change in the electric.

0012<patcit id="pcit0004" dnum="US20040241752A1"><text>US 2004/0241752 A1</text></patcit> discloses systems and methods for medical diagnosis or risk assessment for a patient are provided. These systems and methods are designed to be employed at the point of care, such as in emergency rooms and operating rooms, or in any situation in which a rapid and accurate result is desired. The systems and methods process patient data, particularly data from point of care diagnostic tests or assays, including immunoassays, electrocardiograms, X-rays and other such tests, and provide an indication of a medical condition or risk or absence thereof. The systems include an instrument for reading or evaluating the test data and software for converting the data into diagnostic or risk assessment information. Lateral flow test strips are disclosed.

0013<patcit id="pcit0005" dnum="US6727103B1"><text>US-B1-6727103</text></patcit> relates to a binding assay comprising a machine-readable storage medium which supports a molecular receptor. A support member supports first and second molecular receptors and first and second data identifying the molecular receptors. A support member has a first annular portion to support molecular receptors and a second annular portion to support machine-readable- data identifying the plurality of molecular receptors.

DISCLOSURE OF THE INVENTION

0014The present invention provides a method for performing an immunoassay according to claim 1 and a read-write immunoassay system according to claim 5.

0015Certain embodiments of the invention have other advantages in addition to or in place of those mentioned above. The advantages will become apparent to those skilled in the art from a reading of the following detailed description when taken with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

0016<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> is a read-write assay system according to one embodiment of the present invention;</li><li><figref idref="f0001">FIG. 2</figref> is a lateral flow assay device in one embodiment of the present invention; and</li><li><figref idref="f0001">FIG. 3</figref> is a read-write assay system for using an embodiment of the present invention.</li></ul>

BEST MODE FOR CARRYING OUT THE INVENTION

0017In the following description, numerous specific details are given to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the invention may be practiced without these specific details, and that the essential features are the ones defined in the independent claims. In order to avoid obscuring the present invention, some well-known devices are not disclosed in detail.

0018Likewise, the drawings showing embodiments of the apparatus are semi-diagrammatic and not to scale and, particularly, some of the dimensions are for the clarity of presentation and are shown greatly exaggerated in the FIGs. Where multiple embodiments are disclosed and described having some features in common, for clarity and ease of illustration and description thereof like features one to another will ordinarily be described with like reference numerals.

0019Referring now to <figref idref="f0001">FIG. 1</figref>, therein is shown a read-write assay system 100 according to one embodiment of the present invention. The read-write assay system 100 has a simple read-write device 102 intended to be used in a manufacturing location, a read-write device 104 intended to be used in a home or at a point of care location, and a lateral flow assay device 106.

0020The terms reading and writing are used in the present invention to define writing and reading using a powered write or read device, as contrasted to a writing by printing or handwriting and reading by eye of a printed or handwritten label.

0021The manufacturing location includes the location at which the lateral flow assay device 106 is manufactured, calibrated, packaged, or otherwise processed for an end user. It may even be a physician's office.

0022The point of care location includes a physician's office as well as other sites where the lateral flow assay device 106 can be used.

0023The read-write devices 102 and 104 are electro-magnetic, electronic, optical, or other types of read and write devices to read and write information and data on appropriate media either with or without contact. The read-write devices 102 and 104 are able to read back what has just written and, at a later time read it again without performing an assay or over writing the written information. The initial assay results may be write-protected to prevent over writing for legal reasons. These types of devices can be inexpensive and portable so as to be readily affordable for home use, a physician's office, or at the point of care.

0024The read-write devices 102 and 104 can have simple liquid crystal displays 108 and 110, respectively, for review of the data and simple keypads 112 and 114, respectively, for entry of data. These devices can also be operated individually for single lateral flow assay device 106 or automatically for a number of lateral flow assay devices.

0025Referring now to <figref idref="f0001">FIG. 2</figref>, therein is shown the lateral flow assay device 106 in one embodiment of the present invention. The lateral flow assay device 106 has a multi-layer configuration with a rectangular backing 200 topped by an adhesive 202. For ease of manufacture, the adhesive 202 can be a pressure sensitive adhesive.

0026A sample pad 204 is bonded to the rectangular backing 200 by the pressure sensitive adhesive at one end of the configuration. The sample analyte in a fluid is deposited on the sample pad 204 for assaying.

0027A conjugate pad 206 is located adjacent the sample pad 204. The conjugate pad 206 contains the labeling substance for the analyte to be assayed, forming a conjugate. This conjugate is then mixed with the sample analyte and, if the analyte to be assayed is present in the fluid, the labeling substance will give an indication that the analyte to be assayed is present.

0028A wicking layer 208 of a material such as nitrocellulose is on top of the conjugate pad 206 to promote capillary action and movement of the sample analyte in fluid down the wicking layer 208. The wicking layer 208 preferably has at least two spaced apart lines: a capture line 210 and control line 212. They are preferably at right angles to the lengthwise axis of the rectangular backing 200. The capture line 210 and control line 212 preferably permeate the wicking layer 208 and have easily read widths.

0029An absorbent pad 214 is bonded over an end of the wicking layer 208. The absorbent pad 214 draws the mixed conjugate from the conjugate pad 206 along the wicking layer 208.

0030A read-write pad 216 is bonded over an end of the absorbent pad 214 and the end of the rectangular backing 200 opposite the sample pad 204. The read-write pad 216 is a recording media upon which data can be read and written electro-magnetically, electronically, optically, etc.

0031The read-write pad 216 allows the read-write device 102 of <figref idref="f0001">FIG. 1</figref> at the manufacturer's plant to be used to write lateral flow assay device information. The lateral flow assay device information can include, but is not limited to, manufacturer identity, lot code, device code, calibration information, configuration information, etc.

0032At the time of the assay, specific device information can link the lateral flow assay device 106 with the assay to be performed. The specific lateral flow assay device information can include, but is not limited to, the type of assay the lateral flow assay device 106 actually performs, its shelf life, the correct test conditions (such as time and temperature), etc.

0033The read-write pad 216 allows the read-write device 104 of <figref idref="f0001">FIG. 1</figref> at the point of use to read data to protect against misdiagnosis by using the wrong lateral flow assay device 106.

0034Also, the read-write device 104 could also contain a lateral flow assay device reader to take the actual assay readings. Thus, by providing calibration and/or configuration information, it is possible to improve the accuracy of the results by calibrating and/or configuring the lateral flow assay device reader.

0035Calibration can provide valid and meaningful results for semi-quantitative and quantitative detections. Calibration methods are often critical to provide accurate, reliable and reproducible results, especially when the environments and conditions under which the measurements are commenced are not carefully controlled.

0036Two calibration methods, external and internal calibrations, are commonly employed.

0037In the external calibration method, a standard curve is usually obtained from standard samples containing a series of a known amount of analyte, and the results obtained from the samples are then compared with the standard curve to extract the information regarding the presence and/or amount of the analyte in the sample.

0038External calibration methods are often subject to interference from environmental and batch-to-batch variations, and sometimes are not reliable. When an instrument or measuring device is used, it is also subject to interference from the instability of the instrument or device.

0039Configuration information is also valuable such as wavelengths used, intensity of calibration features, background noise, etc. under which the lateral flow assay device reader operates can be provided so it can be adapted to the specific test to provide more accurate and/or sensitive results.

0040After the assay, the read-write device 104 uses the read-write pad 216 to record lateral flow assay related information such as the patient name, chart number, test results, etc. Since the information will be on and associated with the lateral flow assay device 106, manual recording mistakes will be reduced and traceability will be improved. Further, time and date stamps, operator and test item identity can be written to additionally improve traceability, reduce the possibility of testing mistakes, identity mistakes, etc.

0041As a further benefit, the lateral flow assay device 106 provides a means to correlate test results among operators and/or lateral flow assay device readers.

0042Referring now to <figref idref="f0001">FIG. 3</figref>, therein is shown a read-write assay system 300 for using an embodiment of the present invention. The read-write assay system 300 includes providing an assay device, and writing assay device information to the assay device for subsequent reading of the assay device information from the assay device in a block 302, or performing an assay with the assay device, and writing of the assay related information to the assay device or reading of assay related information from the assay device in a block 304.

0043As usage becomes more common and includes monitoring a condition with multiple assays over a period of time, it will become increasingly valuable to provide a means of traceability on the assay strip, e.g. time and date stamps." Another use that may be valuable is as evidence in legal proceedings, e.g. DUI cases.

0044Thus, it has been discovered that the read-write assay system of the present invention furnish important and previously unavailable solutions, capabilities, and functional advantages for lateral flow assay devices.