JP2009174891A - Microchip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microchip capable of holding a sample liquid in a capillary cavity, and determining the sample, even if an impact, such as, a drop is given to the microchip. <P>SOLUTION: This microchip having a porous film filter on an inlet is equipped with the inlet for collecting liquid which is to be a sample by the action of capillary force; the capillary cavity connected to the inlet, for metering the liquid collected, beforehand; and a holding chamber connected to the capillary cavity for holding the liquid metered, beforehand. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a microchip for electrochemically or optically analyzing biological fluids.

  Conventionally, there is a method of electrochemically or optically analyzing a biological fluid using a microchip in which a microchannel is formed. As a method for electrochemical analysis, as a biosensor for analyzing a specific component in a sample solution, for example, a current value obtained by a reaction between glucose in blood and a reagent such as glucose oxidase supported in the sensor is obtained. Some measure blood glucose levels by measuring them.

  In the analysis method using a microchip, the fluid can be controlled using a rotating device having a horizontal axis, and the sample liquid is measured, the cytoplasmic material is separated and separated using a centrifugal force. Therefore, various biochemical analyzes can be performed.

  As a conventional sample solution collecting method for introducing a sample into a microchip, there is an electrochemical biosensor shown in FIG. 5, and the sample solution is introduced into the cavity 212 by capillary action from the suction port 208, and the working electrode 201, It is guided to a position where the counter electrode 202 and the reagent layer 210 are located. At this time, the sample is quantitatively collected with the volume of the cavity 212. The current value generated by the reaction between the sample solution and the reagent at the working electrode 201 and the counter electrode 202 is connected to an external measuring device (not shown) through the leads 203 and 204 and read (for example, refer to Patent Document 1).

  In the centrifugal transfer type biosensor shown in FIG. 6, the sample liquid is quantitatively collected from the inlet 313 into the first capillary cavity 312 by capillary action, and then the centrifugal force is applied to the sample liquid in the capillary cavity 312. The liquid is transferred to the receiving cavity 317 via the first flow path 314, and the reagent that has reacted with the reagent in the receiving cavity 317 is centrifuged, and only the solution component is collected in the second cavity 316 by capillary force, and optically collected. (See, for example, Patent Document 2).

Further, in the centrifugal transfer biosensor shown in FIG. 7, the sample is transferred from the inlet port 409 to the outlet port 410 by capillary force, and each capillary cavity 404a-f is filled with the sample solution, and then generated by rotation of the biosensor. The sample solution in each capillary cavity is distributed at the position of each vent hole 406a-g by centrifugal force, and transferred to the next processing chamber (not shown) through each connected microconduit 407a-f (for example, , See Patent Document 3).
JP 2001-159618 A Japanese National Publication No. 4-504758 JP-T-2004-529333

  However, in the conventional configuration, when the microchip is accidentally dropped in a state where the capillary cavity is filled with the sample liquid, the sample liquid held in the capillary cavity flows into the chamber and the sample cannot be quantified. It had the problem that.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a microchip capable of quantifying a sample by holding a sample liquid in a capillary cavity even when an impact such as dropping is applied to the microchip. .

  In order to solve the above-described conventional problems, the microchip of the present invention includes an inlet for collecting a liquid, a capillary cavity connected to the inlet for measuring a previously collected liquid, and the capillary And a holding chamber for holding a previously weighed liquid connected to the cavity, and having a porous membrane filter at the inlet.

  According to the microchip of the present invention, even when an impact such as dropping the microchip in a state where the sample liquid is filled in the capillary cavity is given, the sample liquid after quantification is leaked to other channels or the like. Therefore, it is possible to realize a microchip that can ensure the quantitativeness of the sample liquid.

  Hereinafter, embodiments of the microchip of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a microchip 100. FIG. 1A shows the upper substrate 9 of the microchip 100, and FIG. 1B shows the lower substrate 10 of the microchip 100. As shown in FIG. 1, the microchip 100 is configured by bonding an upper substrate 9 and a lower substrate 10 together. A surface of the lower substrate 10 facing the upper substrate 9 is formed with a microchannel structure having fine irregularities, and is formed so that it can function for transferring and holding the sample liquid, respectively. The injection port 1 has a shape protruding from one side surface of the microchip 100 main body, so that it can be easily spotted by a fingertip or the like. It has the effect of preventing it.

  In FIG. 1 (b), a sample liquid such as blood injected into the inlet 1 provided with the porous membrane filter 2 is temporarily held in the holding chamber 4 by a predetermined amount via the capillary cavity 3. The holding chamber 4 carries an analysis reagent (not shown). Then, when the sample solution and the analysis reagent are mixed and the mixing of the reagent and the sample solution reaches a predetermined level, the sample solution in the holding chamber 4 passes through the flow path 6 by the capillary force and enters the measurement chamber 5. And is transferred to the measurement chamber 5 using a centrifugal force generated by rotating the microchip 100 at a predetermined rotational speed.

  The measurement chamber 5 communicates with a capillary channel 7 having an air opening hole 8. The mixture of the sample liquid and the analysis reagent transferred to the measurement chamber 5 is analyzed by measuring predetermined items by an optical method. In the measurement of the sample solution, the measurement chamber 5 is irradiated with light, and the reaction state between the sample solution to be examined and the analysis reagent is optically analyzed. Since the absorbance changes depending on the rate of reaction between the sample solution and the analysis reagent, predetermined items are measured by measuring the absorbance of the irradiated light, and the reaction state can be analyzed.

  FIG. 2 shows an enlarged view of the injection port and the vicinity of the injection port in the microchip 100 according to the first embodiment of the present invention. 2A is a perspective view of the inlet 1, FIG. 2B is a front view of the inlet 1, and FIG. 2C is a cross-sectional view of the inlet 1. The broken lines shown in FIGS. 2B and 2C indicate the upper substrate 9. In this embodiment, the capillary cavity 3 of the microchip 100 has a rectangular shape when viewed from the side where the sample is deposited, that is, from the A direction. The porous membrane filter 2 is installed at the inlet of this inlet. The sample liquid introduced through the porous membrane filter 2 has a structure that does not leak from the inlet 1 and the capillary cavity 3 even when it receives an impact due to the drop of the microchip 100.

  In the present example, the thickness of the inlet was set such that the sample liquid flows by capillary force. The thicknesses of the capillary cavities 3, the flow paths 6, and the flow paths 7 may be appropriately selected as long as the sample solution flows by capillary force. When the sample to be measured is blood, it is preferably 0.02 to less than 0.3 mm. A porous membrane filter 2 is provided in the injection port 1 without any gap. The diameter of one hole of the porous membrane filter 2 used here is at least larger than the diameter through which red blood cells can pass in order to be introduced into the capillary cavity 3. The size of the microchip 100 is configured such that the thickness of the lower substrate 10 in which the microchip 100 is integrated is 5 mm, the thickness of the upper substrate 10 is 1 mm, and approximately 65 mm square. These dimensions can be changed as appropriate in order to obtain an appropriate size for the sample liquid collecting part.

  On the other hand, the thickness of the holding chamber 4 connected to the capillary cavities 3 and formed on the lower substrate 10 is t = 0.3 mm to 0.5 mm, which is thicker than the thickness of the capillary cavities 3 (that is, the thickness of the flow path). Form. By setting in this way, the sample liquid injected into the capillary cavity 3 does not proceed to the holding chamber 4 only by the capillary force, and uses the centrifugal force obtained by rotating the microchip 100 to obtain the sample liquid. It is for transporting. The thickness of each chamber can be adjusted by the amount of the sample solution and the conditions for measuring the absorbance (optical path length, measurement wavelength, sample solution reaction concentration, reagent type, etc.). Then, the sample liquid transferred to the measurement chamber 5 is optically measured. As long as the capillary force acts, the cross-sectional shape of the capillary cavity 3 may be other than a rectangular shape. For example, the same effect can be obtained even in a circular shape or an elliptical shape.

  Furthermore, the wall surface and the porous membrane filter 2 constituting the inlet 1 are formed of a hydrophilic material so that the contact angle is less than a predetermined angle. Specifically, it is provided so that the contact angle with the wall surface of the injection port 1 is less than 90 degrees, which is generally called hydrophilic. Naturally, the smaller the contact angle, the easier it is for the sample liquid to travel in the flow path, which means that the capillary force works strongly. Examples of the hydrophilic treatment method include a surface treatment method using an active gas such as plasma, corona, ozone, and fluorine, and a surface treatment using a surfactant or a hydrophilic polymer.

  FIG. 3 shows the difference in the flow pattern when subjected to an impact depending on the presence or absence of the porous membrane filter 2 which is a feature of the present invention, and the effects of the present invention will be described. FIG. 3A shows a case where a porous membrane filter 2 is provided at the inlet 1 protruding from the microchip 100, and FIG. 3B shows the same shape as that shown in FIG. Show. Also, (1) in FIG. 3 is a diagram immediately after the sample solution is spotted, (2) in FIG. 3 is a diagram after impact by dropping, (c) in FIG. The movement when re-potting by attaching is shown. The diagonal lines in the figure indicate the sample solution, and the shaded area indicates the porous membrane filter 2.

  In this embodiment, W = 5 mm in consideration of the liquid diameter of the sample liquid spotting the width W of the inlet 1. Further, the thickness of the injection port 1 was set to t = 0.1 mm similarly to the capillary cavity 3. A porous membrane filter 2 was provided in the inlet 1 without any gaps, and the dimensions of the porous membrane filter 2 were a width W = 5 mm, a thickness t = 0.1 mm, and a length L = 3 mm. The material used is polyurethane, but it may be either polystyrene or polyethylene. The porosity of the porous membrane filter 2 was three types of 30, 60, and 80%.

  FIG. 3A shows an embodiment of the present invention. For this, a porous membrane filter 2 having a porosity of 60% was used. The size of the microchip 100 was configured such that the thickness of the lower substrate 10 in which the microchip 100 is integrated is 5 mm, the thickness of the upper substrate 10 is 1 mm, and approximately 65 mm square. The weight of the microchip 100 was about 20 g. In the impact test, blood as a sample was filled in the microchip 100 in the injection port 1 and then dropped onto wood from a height of 1 m to confirm the effect of the porous membrane filter 2. The effect of the porous membrane filter 2 was confirmed. FIG. 3A shows a microchip 100 provided with a porous membrane filter 2, and FIG. 3B shows a conventional microchip 100 without the porous membrane filter 2.

  FIGS. 3 (a) and 3 (b) show the state of blood flow in the inlet 1 after impact, respectively. 3A, the sample liquid is held in the inlet 1 even after an impact is applied, but in FIG. 3B, the sample liquid held in the capillary cavity is held in the holding chamber. 4 or the injection port 1, and almost no sample liquid remained in the capillary cavity 3.

  After that, the situation when spotted again is shown in (3) of FIGS. 3 (a) and 3 (b). In FIG. 3A, the sample liquid can be continuously collected from the first spotting, and can be repeated any number of times until the capillary cavity 3 is filled, and a predetermined amount of the sample liquid can be reliably collected. However, when spotted again in (3) of FIG. 3B, the sample liquid has flowed into the holding chamber 4 because the connection between the inlet 1 and the holding chamber 4 is wet.

  Therefore, in the conventional microchip 100, the sample liquid once flows into another flow path, and the capillary cavity 3 for quantifying the sample liquid does not function, and the microchip 100 cannot be used again. By installing the porous membrane filter 2 at the inlet 1 as in the present invention, the sample liquid held in the capillary cavity 3 can be scored without causing leakage due to an impact such as dropping or vibration.

  FIG. 3A shows the effect of the microchip 100 provided with the porous membrane filter 2 having a porosity of 60%. Similar experiments were conducted using porous membrane filters having a porosity of 30% and 80%. This was carried out in the microchip 100 provided. As a result, even in the microchip 100 provided with the porous membrane filter having the porosity of 30% and 80%, good results shown in FIG. 3A were obtained.

  The microchip of the present invention is useful as an analytical device used for measuring components of biological fluids with an electrochemical sensor or an optical sensor.

The disassembled perspective view of the microchip in Embodiment 1 of this invention (A) Perspective view of the inlet and the vicinity of the inlet in Embodiment 1 of the present invention (b) Front view of the inlet and the vicinity of the inlet in Embodiment 1 of the present invention (c) Embodiment 1 of the present invention Sectional view of the inlet and the vicinity of the inlet The figure which shows the flow pattern of the microchip in Embodiment 1 of this invention. The figure for demonstrating the structure of the electrochemical type biosensor of a prior art example The figure for demonstrating the structure of the centrifugal transfer type biosensor of a prior art example. The figure for demonstrating the sample liquid distribution structure of the centrifugal transfer type biosensor of a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inlet 2 Porous membrane filter 3 Capillary cavity 4 Holding chamber 5 Measurement chamber 6, 7 Flow path 8 Atmospheric opening 9 Upper substrate 10 Lower substrate 100 Microchip 201 Working electrode 202 Counter electrode 203, 204 Lead 205 Insulating substrate 206 Cover 207 Spacer 208 Suction port 209 Air escape hole 210 Reagent layer 212 Cavity 310 Wall 312 First cavity 313 Inlet 314 Flow path 315 Filter material 316 Upper compartment 317 Low compartment 318 Core 401 Continuous microconduit 402, 403 Upper part 404a-f Capillary cavity 405a-e Conduit portion 406a-g Top vent 407a-f Connected microconduit 408a-f Valve function 409 Inlet port 410 Outlet port

Claims (8)

An inlet for collecting liquid;
A capillary cavity for metering previously collected liquid connected to the inlet;
A holding chamber connected to the capillary cavity for holding previously metered liquid, and
A microchip comprising a porous membrane filter at the inlet. The microchip according to claim 1, wherein the inlet collects the liquid by an action of capillary force. The microchip according to claim 1, wherein wall surfaces of the capillary cavity and the holding chamber are hydrophilic. The microchip according to claim 1, wherein the porosity of the porous membrane filter is 30 to 80%. The microchip according to claim 1, wherein the porous membrane filter is hydrophilic. The microchip according to claim 1, wherein the pore diameter of the porous membrane filter is a diameter through which red blood cells contained in the liquid pass. The microchip according to claim 1, wherein the height and width of the porous membrane filter are equal to the height and width of the inlet. The microchip according to claim 1, wherein the porous membrane filter uses any one of polystyrene, polyurethane, and polyethylene.

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