JP3060991B2 - Biosensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biosensor, and more particularly, to a biosensor using a sensor chip mounted on a cartridge.

[0001]

2. Description of the Related Art An enzyme-based biosensor is for quantifying a specific substance in a composite sample by utilizing the excellent substrate specificity of the enzyme. Currently, the main method used is
1) a method of converting an enzyme reaction amount into a color change by combining an enzyme and a coloring reagent and optically quantifying the change; and 2) quantifying the enzyme reaction amount by converting an enzyme reaction amount into an electric signal by combining an electrode or a transistor with an enzyme. There are two ways. In particular, the latter device for converting to an electric signal has been rapidly expanding its use in recent years, mainly for chemical analysis and clinical test equipment, because the device is small and inexpensive. A typical example is a biosensor in which an enzyme is immobilized on an electrode or a field effect transistor.

Among such biosensors utilizing an electrochemical reaction, a so-called planar type in which electrodes and transistors are formed on a flat plate is suitable for miniaturization because it can be manufactured using semiconductor fine processing technology. Excellent mass productivity. In general, the sensor chip is housed in a liquid-tight cartridge and used. This is because the sensor is usually used in contact with a liquid such as blood or urine, and its purpose is to ensure waterproofness of the connecting portion, protect the sensor chip, and facilitate replacement. Examples of such a biosensor can be found in JP-A-7-159366 and JP-A-8-247987.

FIG. 9 is a schematic view showing an example of a conventional biosensor. FIG. 9A is a plan view, and FIG.
It is the fragmentary sectional view cut | disconnected by the AA 'line of (a). The sensor substrate 101 is provided with an enzyme electrode, a field-effect biosensor, etc., which is a substrate sensitive part, near one end, and a terminal 105 for electrically connecting the sensor to an external main body at the other end. In the figure, the main body is omitted. The sensor substrate 101 is housed in a cartridge 102. The sensitive portion 103 of the sensor substrate 101 is provided in the cartridge 102.
An opening 104 is provided at a position corresponding to the above. An O-ring 108 is provided on the back surface of the opening 104, and the sensor substrate 101 is kept liquid-tight except for the sensitive portion 103. In addition, a mortar-shaped tapered portion 106 is provided around the opening 104.

Next, a method of using this sensor will be described. FIG. 10 is a schematic sectional view showing how to use this sensor. First, a test liquid 114 such as urine is placed in a cup 120 as shown in FIG. 10A, and the cartridge 102 is immersed in the test liquid 114 such that the opening 104 is completely immersed in the liquid. Here, since the tapered portion 106 is provided around the opening 104, no air bubbles remain in the opening 104, and the test liquid 114 quickly contacts the sensitive portion 103.
Next, a predetermined operation such as applying a voltage between the electrodes and measuring a current is performed. When the measurement is completed, the cartridge 102 is pulled up from the test liquid 114. At this time, test liquid 1
Reference numeral 14 denotes the cartridge 102 through the tapered portion 106 by gravity or centrifugal force applied by a human hand.
Is discharged outside. Next, the cartridge 102 and the sensitive part 103 are washed with water or the like, and the next measurement is performed. Although the above measurement is performed by immersing the cartridge in the liquid, the same measurement can be performed by dropping the test liquid 114 into the opening 104. In this case, there is an advantage that the amount of the test liquid 114 can be extremely small.

[0005]

However, such a biosensor has a problem that an error easily occurs and a response is slow. FIG. 10B shows the cartridge 102.
When the cartridge 10 is pulled up from the test liquid 114
FIG. 4 is a schematic cross-sectional view showing a state 2; In the conventional biosensor, since there is a step between the end surface of the opening 104 and the tapered portion 106, the opening 10
4, the test liquid 114 remains. This test liquid 114
Can be removed by washing, but this time the washing liquid remains in the opening 104. When the next measurement is performed as it is, the cleaning liquid mixes with the second test liquid 114, causing an error in the measurement. In particular, in the method of dropping the test liquid 114 into the opening 104, the amount of the test liquid 114 involved in the measurement is small, so that the error becomes extremely large. Further, even when the amount of the test liquid 114 is large and the error can be ignored as in the immersion method, it takes time until the cleaning liquid remaining in the opening is completely replaced with the test liquid 114,
As a result, accurate measurement cannot be performed unless the measurement time is lengthened.

The above-mentioned adverse effects can be solved by sucking the liquid remaining in the opening 104 with paper or blowing it off with an air gun. It is not preferable because there is a possibility that the 103 will be damaged.

[0007] The present invention has been made to solve the above problems, and an object of the present invention is to provide a biosensor which can perform highly accurate measurement in a short time and is easy to handle.

[0008]

In order to solve the above-mentioned problems, in the biosensor of the present invention, a sensor chip, a cartridge for holding the sensor chip in a liquid-tight manner, and the cartridge being a sensitive part of the sensor chip. In a biosensor having an opening at a corresponding position, the biosensor has a drainage groove communicating the opening of the cartridge and one end of the cartridge. Further, it preferably has a mortar-shaped tapered portion around the opening. More preferably, the second groove is provided in a different direction from the groove.

Preferably, the sensor chip and the cartridge are liquid-tightly connected at the opening by a water-resistant double-sided tape.

[0010] Alternatively, the surface of the cartridge is hydrophobic, and has a hydrophilic portion communicating the opening of the cartridge and one end of the cartridge. The surface of the cartridge is hydrophobic, and the hydrophilic portion is formed by a hydrophilic treatment, formed by a hydrophilic coating, or formed by attaching a hydrophilic sheet.

[0011] Alternatively, the cartridge is formed of a hydrophilic member and is subjected to hydrophobic treatment except for the hydrophilic portion, or is coated with hydrophobic except for the hydrophilic portion, or is hydrophobic except for the hydrophilic portion. It is formed by sticking a sheet of nature.

[0012]

Next, the present invention will be described with reference to the drawings. (Embodiment 1) The biosensor of the present invention comprises at least a sensor substrate 1, a cartridge 2, a power supply, and a main body having a built-in detection circuit. FIG. 1 is a schematic diagram showing a first embodiment of the present invention. (A) is a plan view,
FIG. 2B is a sectional view taken along line AA ′ of FIG. The body is omitted.

As shown in FIG. 1A, the sensor substrate 1 is housed in a cartridge 2, and the cartridge 2 has an opening 4 at a position corresponding to the sensitive portion 3 of the sensor substrate 1.

The sensor substrate 1 is provided with an enzyme electrode as a substrate sensitive part, a field effect type biosensor, etc. near one end, and a terminal 5 at the other end for electrically connecting the sensor to an external body. ing. In the figure, the main body is omitted. The terminal 5 is fitted in a liquid-tight manner with the connector of the main body during use.

The cartridge 2 is provided with a mortar-shaped tapered portion 6 around the opening 4. Further opening 4
And a drain groove 7 connecting the tip and the tip. FIG.
As shown in (b), a sealing material 8 is provided on the joint surface between the opening 4 and the sensitive part 3 for joining them in a liquid-tight manner. Here, the outer shape of the cartridge 2 is 10 to 100 m in length.
m, the width is 5 to 30 mm, the height is 2 to 10 mm, and the diameter of the opening 4 is 1 to 5 mm. The edge of the opening 4 is desirably a knife edge, but 0.2 to 0.5 mm
There is no problem if there is a vertical part. Further, the width of the drainage groove 7 is set to be substantially the same as the diameter of the opening 4 and is 1 to 5 mm, and the depth is slightly smaller than the thickness of the tapered portion 6.
It is set to 5 mm. Here, the groove 7 is provided so that the opening 4 communicates with the tip of the cartridge 2. However, the groove 7 may be provided so as to communicate the opening 4 with another direction, for example, the side end of the cartridge 2. The diameter of the tapered portion 6 is about twice the diameter of the opening 4 and is 2 to 10 mm, and the angle is 30 to 70 ° with respect to the direction perpendicular to the paper surface.

FIG. 2 is a schematic plan view showing an example of the sensor substrate 1. Here, a case where a current detection type glucose sensor is used will be described. A working electrode 9 made of Pt or carbon, a counter electrode 10, and a reference electrode 11 made of Ag / AgCl are formed on a sensor substrate 1 made of glass, plastic, glass epoxy, or the like, and a lead drawn from each electrode extends to the other end. And is connected to the terminal 5. Each electrode is covered with an insulating film 12 except for the sensitive part 3 and the terminal 5. An enzyme-immobilized membrane is placed on these three electrode systems.
A sensitive film 13 composed of an interfering substance removing film and a restricted permeation film is formed.

An example of a method for manufacturing the sensor substrate 1 will be described below. First, a flexible printed wiring board having a copper wiring formed on a polyimide substrate is prepared. The copper wiring is covered with polyimide except for the region and the terminal which become the three electrodes of the sensitive part. After applying photoresist on this,
The resist is removed only by photolithography in the region that becomes the working electrode 9 and the counter electrode 10. Next, Pt is sputtered to deposit 100 nm. Next, the photoresist is removed by dipping in acetone to form a working electrode 9 and a counter electrode 10.
Next, in the same manner, a region having a thickness of 100 nm
Is formed. Next, this is immersed in an aqueous iron chloride solution to precipitate AgCl on the Ag surface. Thus, the electrode substrate is completed. Next, the sensitive film 13 is formed on the electrode substrate. First, γ-aminopropyltriethoxysilane is dropped on the sensitive part 3 using a dispenser and dried. In addition, Nafion, acetylcellulose, a mixed solution of glucose oxidase and albumin and glutaraldehyde,
Silicone is sequentially dropped and dried to laminate. As the sensor element, a sensor element using a carbon electrode, a sensor element having an enzyme immobilized on a gate portion of a field effect semiconductor, or the like can be used.

Next, the configuration of the cartridge 2 will be described. FIG. 3 is a schematic diagram illustrating the configuration of the cartridge 2.
The material of the cartridge 2 is a plastic material such as ABS or polystyrene. The cartridge 2 is divided into upper and lower parts as shown in the figure, and the sensor substrate 1 is mounted between them. At the time of mounting, the position of the sensitive part 3 and the position of the opening 4 are matched, and a sealing material 8 having an opening larger than the opening 4 is sandwiched between the two. The thickness of the sealing material 8 is suitably about 0.1 mm. In this state, the upper and lower cartridges 2 are joined with an adhesive or a screw. An O-ring, a water-resistant double-sided tape, or the like can be used as the sealing material 8, but using a double-sided tape facilitates positioning and improves workability.

Next, the operation of the biosensor of the present invention will be described. FIG. 4 is a schematic sectional view showing a measuring method.
First, the cartridge 2 is immersed in the sample liquid so that the opening 4 is completely immersed in the sample liquid 14 as shown in FIG.
In this state, measurement is performed for a predetermined time. In the current detection type glucose sensor, 0.4 to 0.7 V is applied between the reference electrode and the working electrode, and the current value between the working electrode 9 and the counter electrode 10 is measured. The measurement is completed in about 10 seconds. When the measurement is completed,
Take out the cartridge 2 from. Next, as shown in FIG. 4 (b), when the end of the drainage groove 7 is turned downward, the sample liquid 14 remaining in the opening 4 passes through the drainage groove 7 by the action of gravity and is directed in the direction of the arrow in the figure. Is quickly discharged. Next, the cartridge 2 is washed with distilled water or the like. Cleaning water is also drainage groove 7
From the opening 4 immediately. Therefore, even if the next measurement is immediately performed, the sample liquid 14 and the washing water do not mix. Further, even if the next measurement is performed continuously, since no washing water or the like remains in the opening 4, a new sample solution 14
Quickly comes into contact with the sensitive part 3. Thus, the accuracy of the measurement was improved, and the measurement time was shortened. In the above example, the test liquid 14 placed in the container was measured, but the test liquid 14 may be dropped directly on the opening 4.

FIG. 5 shows the results when the measurement of urine and the washing with distilled water are repeated using this biosensor. For comparison, the results of measurement with a biosensor having no drainage groove 7 are also shown. As is clear from this graph, the measurement accuracy was improved by the present invention. The response time until the output was saturated was also reduced from about 30 seconds to about 5 seconds. (Embodiment 2) FIGS. 6A and 6B are schematic views showing a second embodiment of the present invention, wherein FIG. 6A is a plan view and FIG. 6B is a sectional view. The surface of the cartridge 2 of the present embodiment is hydrophobic, and a hydrophilic region 15 is formed only near a line segment having one end as the opening 4 and the other end as the tip of the cartridge 2. Its width is about the same as the diameter of the opening 4 and 1 to 5 mm
It is about. The other end of the hydrophilic region 15 may be an end surface other than the end of the cartridge 2. The other configuration is the same as that of the first embodiment except that there is no drainage groove 7. The simplest configuration of the present embodiment is that the cartridge 2 is made of a hydrophobic material, for example, polyethylene, polypropylene, ABS resin, polystyrene, polytetrafluoroethylene, and the like, and a predetermined area is subjected to a hydrophilic treatment. Here, the hydrophobic material is defined as a material having a contact angle of water of 80 ° or more. Further, as a hydrophilic treatment, after masking the unnecessary portion, an aqueous solution containing chromic acid as a main component (K ₂ Cr ₂ O ₇ :
H ₂ SO ₄ : H ₂ O = 75 g: 150 g: 120 g) or a method of dipping in a sulfuric acid solution heated to about 80 ° C. is typical. More simply, a silane coupling agent having a hydrophilic group such as γ-aminopropyltriethoxysilane or 3- (2-aminoethylaminopropyl) trimethoxysilane may be applied only to a predetermined region. Here, the hydrophobic material is defined as a material having a contact angle of water of 80 ° or more. Alternatively, a hydrophilic sheet such as polyvinyl alcohol or polymethyl acrylate having a thickness of about 0.1 mm may be attached.

Contrary to the above-described method, the cartridge 2 is formed of a hydrophilic material such as polyvinyl alcohol, polymethyl acrylate, and poly (hydroxyethyl methacrylate). A hydrophobic treatment may be performed by applying a silane coupling agent such as ethoxysilane or dimethylpolysiloxane, or may be formed by attaching a hydrophobic sheet such as polyethylene or polypropylene. Here, the hydrophilic material is defined as a material having a water contact angle of 60 ° or less.

FIG. 7 is a schematic diagram showing the concept of drainage of the biosensor. The test liquid 14 remaining in the opening 4 is drawn by the surface tension in the direction indicated by the arrow in the figure, and is quickly discharged downward in the figure.

Further, if the hydrophilic treatment of the present embodiment is performed on the drain groove 7 of the first embodiment, the drainage efficiency is further improved. (Embodiment 3) FIGS. 8A and 8B are schematic views showing a third embodiment of the present invention, wherein FIG. 8A is a plan view and FIG. 8B is a sectional view. In this embodiment, an introduction groove 16 for introducing a test liquid is added to the cartridge 2 in addition to the drainage groove 7 for draining liquid in the first embodiment. When the cartridge 2 is often immersed in the liquid in the container, the introduction groove 16 is preferably provided at the rear end side of the cartridge 2 in the opening 4. This makes it easier for bubbles adhering to the opening 3 to move upward, so that measurement failure due to remaining bubbles is reduced. Further, the width and the depth may be substantially the same as those of the drainage groove 7, the width is about 1 to 5 mm, the depth is about 1 to 5 mm, and the length is preferably about 5 to 10 mm. Note that the introduction groove 16 is desirably hydrophobic so as not to prevent aggregation of the drainage into the drainage groove 7.

On the other hand, in a biosensor for analyzing urine, released urine may be directly used. In this case, there is a possibility that the urine which has once entered the opening 4 may come out again due to the recoil of the collision. However, when the introduction groove 16 is provided as in the present embodiment, the test liquid 14 can be temporarily stored, so that stable measurement can be performed. In this case, the same effect can be obtained even if the introduction groove 16 is formed in a direction other than the rear end side of the cartridge 2.

[0025]

According to the biosensor of the present invention, an opening is provided at a position corresponding to the sensitive portion of the sensor chip, and the cartridge for holding the opening in a liquid-tight manner communicates the opening with one end of the cartridge. Since the liquid groove 7 or the hydrophilic portion is provided, waste liquid and washing water remaining in the opening after the measurement is completed can be quickly eliminated. For this reason, the accuracy of the test or analysis for quantifying the components in the liquid has been improved, and the time required for the measurement has been reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view and a schematic cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a schematic plan view showing an example of a sensor substrate used in the present invention.

FIG. 3 is a schematic perspective view showing a configuration of a cartridge of the present invention.

FIG. 4 is a schematic sectional view showing an operation according to the present invention.

FIG. 5 is a schematic sectional view showing a measurement example according to the present invention.

FIG. 6 is a schematic plan view and a schematic cross-sectional view showing a second embodiment of the present invention.

FIG. 7 is a conceptual diagram showing an operation of the second exemplary embodiment of the present invention.

FIG. 8 is a schematic plan view and a schematic cross-sectional view showing a third embodiment of the present invention.

FIG. 9 is a schematic plan view and a schematic sectional view of a conventional biosensor.

FIG. 10 is a schematic sectional view showing the operation of a conventional biosensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 101 Sensor board 2, 202 Cartridge 3, 103 Sensing part 4, 104 Opening 5, 105 Terminal 6, 106 Taper part 7 Drain groove 8 Seal material 9 Working electrode 10 Counter electrode 11 Reference electrode 12 Insulating film 13 Sensitive film 14 Test liquid 15 Hydrophilic treatment part 16 Introducing groove 108 O-ring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 27/28 G01N 27/327

Claims (14)

(57) [Claims] 1. A biosensor, comprising: a sensor chip; and a cartridge for holding the sensor chip in a liquid-tight manner, wherein the cartridge has an opening at a position corresponding to a sensitive portion of the sensor chip. A biosensor having a drainage groove communicating between an opening and one end of the cartridge. 2. The biosensor according to claim 1, further comprising a mortar-shaped tapered portion around the opening. 3. The biosensor according to claim 1, further comprising a second groove in a direction different from the groove. 4. The biosensor according to claim 1, wherein said cartridge comprises a water-repellent member. 5. The biosensor according to claim 1, wherein the sensor chip and the cartridge are liquid-tightly connected at the opening with a water-resistant double-sided tape. 6. A biosensor comprising: a sensor chip; and a cartridge for holding the sensor chip in a liquid-tight manner, wherein the cartridge has an opening at a position corresponding to a sensitive portion of the sensor chip. Is hydrophobic, and has a hydrophilic portion communicating the opening of the cartridge and one end of the cartridge. 7. The biosensor according to claim 6, wherein the cartridge is formed of a hydrophobic member, and the hydrophilic portion is formed by a hydrophilic treatment. 8. The biosensor according to claim 6, wherein the cartridge is formed of a hydrophobic member, and the hydrophilic portion is formed of a hydrophilic coating. 9. The biosensor according to claim 6, wherein the cartridge is formed of a hydrophobic member, and the hydrophilic portion is formed by attaching a hydrophilic sheet. 10. The biosensor according to claim 6, wherein the cartridge is formed of a hydrophilic member, and has been subjected to a hydrophobic treatment except for the hydrophilic portion. 11. The biosensor according to claim 6, wherein the cartridge is formed of a hydrophilic member, and is coated with a hydrophobic material except for the hydrophilic portion. 12. The biosensor according to claim 6, wherein the cartridge is formed of a hydrophilic member, and is formed by attaching a hydrophobic sheet except for the hydrophilic portion. 13. The sensor chip according to claim 13, wherein the cartridge is the sensor chip.
Contact the test solution to the sensitive part at a position corresponding to the sensitive part
2. The device according to claim 1, wherein the device has an opening.
Osensor. 14. A communication with one end of the cartridge.
Make sure that the drain groove is exposed on the outer surface of the cartridge.
The bio according to claim 1, which is provided.
Sensor.