Microdialysis-probe integrated with a si-chip

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

In the present invention, a perfusion fluid is brought into contact with a body fluid by a part of a living organism. It contains at least a probe that has an inlet and an outlet for incorporating the components of this body fluid into the perfusate, thereby concentrating the perfusate into a dialysate. Regarding microdialysis machines. [0002]

Such a device is known under US Pat. No. 5.640.954. The device known by this patent relates to a method and device for continuously monitoring the concentration of metabolic intermediates such as glucose and lactic acid in biological tissues. In this method and device, the perfusate is guided by a microdialysis probe inserted into the subcutaneous tissue, thickened by metabolic intermediates from the tissue fluid, and then discharged as a dialysate. According to this method, the enzyme is added to the dialysate and the concentration of metabolic intermediates in the dialysate is measured at an in vitro measurement point under the selective effect of the enzyme by using an electrochemical sensor. To. [0003]

The disadvantage of known microdialysis machines is that they limit the clinical use of microdialysis technology because they use relatively large conventional analysis equipment to analyze the components incorporated into the perfusate, even though they are performed online. There is. This analysis facility must be connected to the tubes used and adapters to the microdialysis probe, the flow rate of which is exceptionally low (on the order of microliters per minute). The resulting dead space combined with a very small sample for analysis becomes a problem. Another drawback of known devices is that connecting separate elements such as hoses and couplings used can cause errors by the practitioner. Yet another drawback is that known devices are, in principle, only suitable for the analysis of predetermined components. This is because the addition of the enzyme makes the dialysate unsuitable for analysis of other components. [0004]

An object of the present invention is microdialysis, which can measure a plurality of components, virtually eliminate the possibility of error by the practitioner, and analyze a very small amount of dialysate by a reliable method with very little waiting time. To provide the device. [0005]

In the present invention, a microdialysis apparatus of the type described above has been proposed for this purpose, in which the outlet of the probe is completely received in the silicon chip and the first flow path in the silicon chip. Outlet is formed. [0006]

Such a device for microdialysis not only offers the advantage that the dead space is considerably smaller than that of the conventional device, but also provides a fragile junction of the entry / exit flow path to the probe within its silicon chip or its housing. It also provides the possibility of an integrated sequence. [0007]

A preferred embodiment of the microdialysis apparatus according to the present invention further includes an analysis means for analyzing the components of the body fluid taken in by the perfusate, and at least one analysis means is that the dialysate flowing from the probe discharge port is the first stream. It is completely accepted in the silicon chip so that it comes into contact with this analytical instrument in the road. [0008]

In one embodiment, at least one analytical means includes a sensor, eg, an ion-sensitive field effect transistor (ISFET). [0009]

In another embodiment, at least one analytical means comprises a fluid storage chamber in a silicon chip. The components in the dialysate come into contact with a sensor provided in the storage chamber through this storage chamber, or the storage chamber contains, for example, a standard fluid having components added to the dialysate in the first flow path. .. [0010]

The presence of specific substances in the dialysate when combined with a fluid reservoir containing standard substances and the concentrations of these measured substances are measured by the sensors used. [0011]

The fluid storage chamber is separated from the first flow path, for example by a semi-permeable membrane, or the storage chamber contains, for example, a gel-like fluid, and the first flow path contains a depression formed in the gel-like fluid. [0012]

In another embodiment, at least one analytical means has a fluid storage chamber comprising a laminated structure of a noble metal and a salt derived from the noble metal, which also contains an electrolyte. The reference electrode integrated into the silicon chip can be used, for example, as a counter electrode of a sensor for measuring potential differences such as pH measurement of dialysate flowing through a flow path. [0013]

In yet another embodiment, the silicone chip has a pumping means for individually pumping the perfusate and dialysate. [0014]

In a preferred embodiment, the pumping means pumps the perfusate and dialysate individually and intermittently. [0015]

Intermittent pumping is the semi-penetration of the probe in a probe that has been inserted into a portion of the organism, for some time at the same location, until the components of the fluid are incorporated into the perfusate in equilibrium, for example. Allows it to be retained until it spreads through the portion. Thus, the dialysate formed can subsequently be pumped to a sensor present within the silicon chip. The dialysate can be kept in contact with this sensor for any sufficiently long period of time. This provides the advantage that the sensor becomes available. These sensors have too long a reaction time and are not suitable for measurements using pumping means that do not perform intermittent pumping. [0016]

Pumping means include, for example, at least one closed storage chamber. The storage chamber is filled with a reversibly expandable medium, an actuator for the medium is provided, and one side of the storage chamber has a movable wall portion. If this movable wall portion also forms part of a tube for perfusate or dialysate, the movable wall portion is selectively combined with a valve appropriately selected and placed in this tube. It can be used to pump the relevant fluid through a tube. [0017]

The expandable medium expands in a physical or physicochemical process, preferably in a reversible manner, eg, as a function of temperature. [0018]

In a preferred embodiment, the expandable medium expands as a function of pH and the storage chamber is provided with electrodes. By using these electrodes, the pH of the expandable medium is changed by the coulometric method. [0019]

In the next embodiment, the silicon chip has a means of administration that administers an additive to each of the perfusate and dialysate. [0020]

These administration means have, for example, an electrode at the first closed outer end and at least a second flow path with the second open outer end exiting into the flow path. [0021] [0021]

By using the administration means, it is possible to accurately administer a small amount of fluid (for example, a standard fluid or a reagent) into the first flow path in the silicon chip in a very small amount unit (on the order of nanoliters). [0022]

However, the use of the pumping means or the administration means according to the present invention is not limited to the microdialysis system. The means of administration is particularly suitable for subcutaneous administration using, for example, a syringe for medication such as an analgesic. [0023]

In a preferred embodiment, the probe inlet is also fully accommodated within the silicon chip. [0024]

In a preferred embodiment of the microdialysis apparatus according to the present invention, the probe has two substantially concentric tubes, the inner tube having a portion protruding from the distal end of the outer tube, which portion is connected to the outer tube. Surrounded by a semi-permeable membrane, there is a through-passage between the inner and outer tubes, the silicon chip has a first hole extending in the longitudinal direction, the first segment, the transition segment, the second segment and The third segment is continuously formed, the inner circumference of the first segment corresponds to the outer circumference of the outer tube, the inner circumference of the second segment corresponds to the outer circumference of the inner tube, and the second hole is in the transition segment. Ejected, extending in a cross-sectional direction, the third hole is ejected within the third segment, the outer tube is received by the proximal end of the first segment, and the portion of the inner tube protruding from the proximal end of the outer tube , The first hole connects to the through-passage between the inner tube and the outer tube and is accepted into the second segment so that the third hole connects to the inside of the inner tube. [0025]

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. [0026]

The same elements are shown with the same drawing numbers in all drawings. [0027]

FIG. 1 shows an integrated microdialysis measurement system 10 according to the present invention, in which the probe 1 is completely contained within a silicon chip 5 covered by a cover 12. The probe 1 consists of a semi-permeable U-shaped tube 4 that is introduced into the tissue of the specimen. In the middle of the foot of the U-shaped tube 4, there is an introduction part 2 and an discharge part 3, each of which is completely accommodated in the silicon chip 5. The U-shaped tube 4 has, for example, a diameter of about 100 μm and a wall thickness of about 10 μm, and is made of cellulose acetate or polycarbonate. The arrow on the right side of the figure indicates the direction of flow of the perfusate and dialysate through probe 1. The arrows on the left in the figure indicate the uptake of components from tissue fluid into the perfusate. The roughly illustrated pump 50 pumps the perfusate in the indicated flow direction and is completely received within the silicon chip 5 in front of the inlet 2 of the U-shaped tube 4. The discharge port 3 of the U-shaped tube 4 continues as a flow path 6 through the silicon chip 5, and further passes through two storage chambers 7, 8 and a reference electrode 9 and a sensor 11. [0028]

FIG. 2 shows a cross section of the silicon chip 5 shown in FIG. 1 cut by lines II-II. This shows how the storage chamber 7 is formed by the indentation of the silicon chip 5. This storage room is made of silicon oxide (SiO)₂) Or silicon oxide (SiO)₂/ Si₃N) and nitriding It is coated with a layer sandwiched between silicon and filled with a gel 14 containing a known concentration of analytical material. The gel 14 contacts the dialysate guided to the measurement system via the semi-permeable membrane of channel 6. [0029]

FIG. 3 shows a cross section of the reference electrode 9 cut along line III-III shown in FIG. The reference electrode 9 consists of a recess within the silicon chip 5, coated with silver or silver chloride (Ag / AgCl) layer 15, filled with a potassium chloride (KCl) solution, which solution is dialysis flowing through the silicon chip 5. The object comes into contact with the object via the semi-permeable membrane of the flow path 6. The depression 16 is not potassium chloride, for example, a properly selected so-called ion exchanger or ion permeable carrier (a substance capable of binding to a specific molecule or ion), or a polyvinyl chloride concentrated by an ion exchanger or an ion permeable carrier. The ion-specific electrode 9 is obtained by filling with a solution containing silicon rubber. [0030]

FIG. 4 is a cross section of the sensor 11 of FIG. 1 cut along the line IV-IV. The sensor 11 consists of a recess 44 in the silicon chip 5 and is made of silicon oxide (SiO).₂) Layer 13 Is coated by. Channel 6 passes through the recess 44. The source and drains 17 and 18 of the ion-sensitive field effect transistor (ISFET) are formed at the bottom of the recess 44, respectively. The ISFET contacts the dialysate in the flow path 6 via the fluid in the recess 44 and the semi-permeable membrane in the flow path 6. The sensitivity of ISFETs can be affected by the choice of fluid in the indentation 44. In an alternative embodiment for sensor 11, there is no semi-permeable wall in channel 6 at the location of recess 44, the ISFET is in direct contact with the dialysate in channel 6, or the recess 44 is filled with gel. , A channel for the hemodialysis station is formed by the indentation 6 in this gel. [0031]

When the storage chambers 7 and 8 of the measurement system 10 are filled with lactic acid solutions having different concentrations, for example, and the sensor 11 is appropriately selected, the system can measure the lactic acid concentration in the tissue fluid online. For measurement, the U-shaped portion of probe 1 is inserted into the relevant tissue and body fluid, respectively, and in a stationary state, lactic acid molecules from the tissue fluid, the standard fluid in the storage chamber 7, and the standard fluid in the storage chamber 8, respectively. Is taken up via a semi-permeable membrane. After a while, the formed dialysate is then fed by a pumping means (not shown) along the direction indicated by the arrow on the right side of the figure, and the sensor 11 produces a concentration-based signal as a function of time. [0032]

FIG. 5 shows the signal of the sensor 11 in the above example, the block on the right shows the signal proportional to the known concentration of the fluid in the storage chamber 8, and the central block shows the signal of the fluid in the storage chamber 7. The signal proportional to the known concentration is represented, and the block on the left represents the signal proportional to the unknown concentration in the tissue fluid. The value of the concentration of interstitial fluid can be obtained from two known concentrations by a simple interpolation method. [0033]

FIG. 6 shows an exploded perspective view of the measurement system 20. The measurement system 20 has a silicon chip 5 with holes formed in the longitudinal direction using micromachining techniques (anisotropic or isotropic silicon etching). This hole consists of a continuous first segment 24, a transition segment 25, a second segment 26, and a third segment 27. Further, the second hole 28 is formed so as to go out into the transition segment 25, and the third hole 29 is formed so as to go out into the third segment 27. Thus, in the hexagonal first segment 24 formed by anisotropic etching, the outer tube 22 of the probe is placed on the transition segment 25 and the inner tube 21 is the second segment 26 through the outer tube 22. Placed on top. At the proximal end of the inner tube 21, a through-passage 43 is created between the inner tube 21 and the outer tube 22 to connect with the cross hole 28 at the transition segment 25, with the inner tube 21 passing through the third segment 27. It is exited into the third segment 27 of the flow path so that it is connected to the third hole 29 at its proximal end. On the distal end of the outer tube 22, a semi-permeable membrane 23 is formed around the portion of the inner tube 21 protruding from the distal end of the outer tube 22. The semi-permeable membrane 23 is closed at the distal end. A liquid leak-free structure is made with the appropriate adhesive introduced via the adhesive hole 31 in the cover 12. The distal end of the integrated microdialysis probe 20 with the semi-permeable membrane 23 is inserted into the tissue to be examined, and then the perfusate is routed through the cross-hole 28, the transition segment 25 and the through-passage 43 (indicated by the left arrow). Introduced, then the uptake of components from tissue fluid to perfusate in the tissue is carried out through the semi-permeable membrane 23, and then the fluid concentrated into the dialysate continues with the inner tube 21, third segment 27 and It is discharged via the third hole 29. The third segment 27 functions as a flow path in which the analysis means (not shown, for example, formed in the sensor surface 42) is completely accepted in the present invention. .. In the integrated probe 20 shown, all dangerous junctions are housed in a silicon chip, so the probe is less fragile than a conventional probe and can be used in a much simpler way. In addition, the dead space within this probe is reduced by about 90% over what is known. [0034]

FIG. 7 shows a dosing system 30 united into a silicon chip 5 to add two fluids to the dialysate flowing through the flow path 6 indicated by the left and right arrows in the figure. The dosing system has two serpentine paths 32, 33 filled with a fluid for dosing, which have electrodes 34, 35 at the first closed outer end and a second open outer end 41, respectively. Is put out in the flow path 6. When an electric current passes through these electrodes via the terminal 36 using the power supply 37, bubbles 38 and 39 are generated at the electrodes 34 and 35, and the bubbles push the fluid out of the flow paths 32 and 33.

[Simple explanation of drawings]

[Figure 1]

It is the schematic perspective view of the microdialysis apparatus which concerns on 1st Embodiment of this invention. [Figure 2]

It is sectional drawing by line II-II of FIG. [Fig. 3]

It is sectional drawing which draws the line III-III of FIG. [Fig. 4]

It is sectional drawing which draws the line IV-IV of FIG. [Fig. 5]

It is a graph which showed the measurement result obtained by using the apparatus concerning FIG. [Fig. 6]

It is the schematic perspective view which cut out a part of the surface of the microdialysis apparatus which concerns on 2nd Embodiment of this invention. [Fig. 7]

It is a schematic perspective view of the administration system for a microdialysis machine.