JP7325614B2 - electrochemical analysis chip - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrochemical analysis chip for measuring the concentration of a specific substance that can be contained in a sample liquid.

Measurements using the principle of electrochemical measurement are typified by highly sensitive measurements of heavy metals in solutions, glucose measurements using enzyme electrodes, pH measurements using ion electrodes, and electrochemical detection of residual pesticides. It is used in many situations such as food inspection in which food is stored (see, for example, Patent Document 1).

It is known that an electrochemical analysis chip having electrodes formed on an insulating substrate can be used in electrochemical measurements. In the electrochemical analysis chip, the electrode basically has a single-layer structure, and the electrode material used is a metal material such as silver, platinum, gold, or aluminum, or a conductive material such as carbon.

By the way, when measuring multiple items simultaneously using a conventional electrochemical analysis chip, a sampling operation was required for each item. However, when the sampling operation is performed for each, density spots (concentration varies depending on the position of the sample specimen, the sampling location, whether it is an early sample or an intermediate sample, etc.) occur, and the measurement accuracy and reproducibility are reduced. was there. In addition, there is a problem that a large amount of sample liquid is required to perform a plurality of sampling operations on the same sample liquid.

JP-A-11-248668

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrochemical analysis chip capable of measuring a plurality of items in one sampling operation.

An electrochemical analysis chip of the present invention includes a sensor section having a plurality of electrodes and provided on an insulating base material, and a channel section provided on the base material for guiding a sample liquid to the sensor section. wherein the substrate is provided with a plurality of the sensor portions, and the flow path portion is provided with a sample liquid supply port opened on the outer surface of the substrate, and the same sample liquid is supplied to the sample liquid supply port. and a sample liquid flow path leading from to the plurality of sensor units.

According to the electrochemical analysis chip of the present invention, the same sample liquid can be led from the sample liquid supply port to the plurality of sensor sections by the sample liquid flow path. A sample liquid can be brought into contact. As a result, even with a very small amount of sample liquid, it is possible to measure a plurality of items with a single sampling operation.

In the electrochemical analysis chip of the present invention, the channel section may include a plurality of sample liquid channels connected to one sample liquid supply port.

According to this aspect, the sample liquid can be introduced into the plurality of sensor units simply by bringing the sample liquid into contact with one sample liquid supply port, so that the sampling operation is easy and the time required for the sampling operation is shortened. can be timed.

In the electrochemical analysis chip of the present invention, the channel section includes the sample liquid supply port and the sample liquid channel for each of the plurality of sensor sections, and the plurality of sample liquid supply ports are connected to the substrate. They may be arranged adjacent to each other on the outer surface of the material.

According to this aspect, by providing the sample liquid supply port and the sample liquid channel for each sensor section, the sample liquid can be reliably introduced to each sensor section. In addition, since the sample liquid supply ports provided for each sensor unit are arranged close to each other on the outer surface of the base material, the sample liquid can be reliably brought into contact with the sample liquid supply ports in one sampling operation. can improve the certainty of the sampling process.

In the electrochemical analysis chip of the present invention, the sensor section is provided on an electrode chip that can be attached to the substrate, and the substrate has an opening on the outer surface of the substrate into which the electrode chip is inserted. The sample liquid flow path is connected to the electrode chip placement section, and the sample liquid flows between the inner wall of the electrode chip placement section and the electrode chip by capillary action. A gap may be provided through which the liquid penetrates from the liquid flow path toward the opening of the electrode chip arrangement portion.

According to this aspect, by exchanging the electrode tip according to the measurement item, it is possible to cope with a large number of measurement items, so that versatility is improved.

In the electrochemical analysis chip of the present invention, the substrate is formed by stacking a base substrate on which the sensor section is formed, a flow path substrate forming the flow path section, and a cover substrate covering the flow path substrate. may be configured.

According to such an aspect, by integrating the sensor section with the base substrate, it is possible to reduce the size of the electrochemical analysis chip.

In the electrochemical analysis chip of the present invention, the sensor unit includes a working electrode and a reference electrode as the electrodes, or includes a working electrode, a reference electrode, and a counter electrode, and the electrode is an insulating substrate. a metal layer formed on the substrate; a carbon layer formed on the substrate overlying the metal layer; and an upper adhesion layer formed between a top surface of the metal layer and the carbon layer. , the upper adhesive layer may be made of silicon.

According to this aspect, since each electrode has a metal layer, the electrical resistance can be lowered and the measurement sensitivity can be improved. In addition, by covering the metal layer with the carbon layer, the metal layer can be prevented from being oxidized and reduced, and the measurement sensitivity and reproducibility can be improved. Furthermore, by providing an upper adhesion layer made of silicon between the upper surface of the metal layer and the carbon layer, the adhesion between the metal layer and the carbon layer is improved, and silicon has a higher electrical resistivity than metal. Since it is high, it is possible to suppress the generation of hydrogen on the upper surface of the metal layer during measurement, prevent separation between the metal layer and the carbon layer, and improve measurement sensitivity and reproducibility.

The present invention can provide an electrochemical analysis chip that can measure a plurality of items in one sampling.

It is a schematic block diagram which shows an example of an electrochemical measuring apparatus. 1 is a plan view showing an embodiment of an electrochemical analysis chip; FIG. It is an isolation|separation perspective view of the same electrochemical-analysis chip. It is a side view center longitudinal cross-sectional view of the same electrochemical analysis chip. It is a schematic plan view showing an electrode tip. FIG. 6 is a schematic cross-sectional view corresponding to the AA position of FIG. 5; FIG. 10 is a graph showing current-potential curves obtained using an electrode tip attached to an embodiment and a comparative tip. FIG. It is a microphotograph of the working electrode of the electrode tip and the comparative tip after measurement taken from the substrate side, (A) showing the embodiment (electrode tip) and (B) showing the comparative example (comparative tip). FIG. 4 is a schematic cross-sectional view showing another configuration of the electrode tip; FIG. 3 is a plan view showing another embodiment of an electrochemical analysis chip; FIG. 4 is a plan view showing still another embodiment of an electrochemical analysis chip; It is an isolation|separation perspective view of the same electrochemical-analysis chip.

An embodiment of an electrochemical analysis chip will be described based on the drawings. FIG. 1 is a schematic configuration diagram showing an example of an electrochemical measurement device. FIG. 2 is a plan view showing one embodiment of an electrochemical analysis chip. FIG. 3 is an exploded perspective view of the same electrochemical analysis chip. FIG. 4 is a side view central longitudinal sectional view of the same electrochemical analysis chip. 2, illustration of the cover substrate 213 is omitted. Moreover, in FIG. 4, the thickness of each member is enlarged and illustrated for convenience.

As shown in FIG. 1, an electrochemical measurement device 1 includes an electrochemical analysis chip 2, a potentiostat 3 connected to the electrochemical analysis chip 2, an operation unit 4 connected to the potentiostat 3, a display unit 5, A power supply unit 6 and an external output unit 7 are provided. In this embodiment, the electrochemical analysis chip 2 is disposable.

As shown in FIGS. 2 to 4, the electrochemical analysis chip 2 includes an insulating base material 21, a plurality of sensor units 22 provided on the base material 21, and a sample liquid provided on the base material 21. and a channel portion 23 leading to the sensor portion 22 . Although three sensor units 22 are provided in this embodiment, the number of sensor units may be two or four or more in the electrochemical analysis chip of the present invention.

The substrate 21 is configured by disposing a cover substrate 213 on a base substrate 211 with a channel substrate 212 interposed therebetween. The base substrate 211, the channel substrate 212, and the cover substrate 213 are composed of substantially rectangular insulating substrates.

The channel substrate 212 has a cutout portion 214 into which the electrode chip 24 having the sensor portion 22 can be inserted, and a groove 215 for forming the sample liquid supply port 231 and the sample liquid channel 232 that constitute the channel portion 23 . is formed. In this embodiment, three cutouts 214 are formed.

The notch 214 is open to the first side surface 212 a of the channel substrate 212 and has a width slightly larger than the width of the electrode tip 24 . An electrode chip placement portion 216 is formed by covering the notch portion 214 with the base substrate 211 and the cover substrate 213 .

The groove 215 is formed on one surface of the flow path substrate 212, extends from a second side surface 212b facing the first side surface 212a of the flow path substrate 212 toward the first side surface 212a, and branches into three grooves in the middle. and connected to the three notches 214 . By covering the groove 215 with the cover substrate 213, the sample liquid supply port 231 opened to the outer surface of the base material 21 (the second side surface 212b of the channel substrate 212) and the same sample liquid can be supplied from the sample liquid supply port 231. A channel portion 23 having a sample liquid channel 232 leading to the sensor portion 22 is formed.

Materials of the insulating substrates constituting the base substrate 211, the channel substrate 212, and the cover substrate 213 are not particularly limited, and examples thereof include glass, quartz glass, polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), and polyethylene. (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyoxymethylene (POM), ABS resin (ABS), methacrylic resin (PMMA), and the like. Moreover, the shape, thickness and size of the insulating substrate are not particularly limited.

Also, the sample liquid supply port 231 and the sample liquid channel 232 have dimensions that allow the sample liquid to be introduced from the sample liquid supply port 231 into the sample liquid channel 232 by capillary action and lead to the sensor section 22. good. Further, a hydrophilic treatment layer for improving wettability may be formed on the inner wall surface of the sample liquid channel 232 (the inner wall surface of the groove 215 and the joint surface of the cover substrate 213 with the channel substrate 212).

As shown in FIGS. 3 and 4, the substrate 21 of the electrochemical analysis chip 2 is formed by stacking and integrating a base substrate 211, a channel substrate 212 and a cover substrate 213 in this order. Adhesives or heat-sealing can be used to join the base substrate 211 and the channel substrate 212 and to join the channel substrate 212 and the cover substrate 213, for example.

An electrode chip 24 having a sensor portion 22 is attached to the electrode chip placement portion 216 of the base material 21 . The electrode chip 24 has a flat insulating substrate 241 on which a working electrode 242, a counter electrode 243 and a reference electrode 244 are provided insulated from each other. The substrate 241 has a substantially rectangular shape in plan view. The working electrode 242 , the counter electrode 243 and the reference electrode 244 are provided from near one end to near the other end in the longitudinal direction of the substrate 241 . The working electrode 242 , the counter electrode 243 , and the reference electrode 244 are covered with an insulating layer 245 formed on the substrate 241 at their longitudinal midpoints. One end side of the working electrode 242 , the counter electrode 243 and the reference electrode 244 constitutes the sensor section 22 .

By inserting one end side of the electrode chip 24 into the electrode chip placement portion 216 of the substrate 21, the sensor portion 22 (one end sides of the working electrode 242, the counter electrode 243, and the reference electrode 244) is placed inside the electrode chip placement portion 216. be done. Between the inner wall of the electrode tip placement portion 216 and the electrode tip 24, the sample liquid introduced into the flow path portion 23 by capillary action flows to the opening side (first side surface 212a side) of the electrode tip placement portion 216 by capillary action. A small gap is formed to the extent that it penetrates into.

The size of the gap between the inner wall of the electrode tip placement section 216 and the electrode tip 24 is large enough for the sample liquid to permeate from the sample liquid flow path 232 toward the opening of the electrode tip placement section 216 by capillary action. There is no particular limitation as long as it is small. In addition, the inner wall surface of the electrode chip placement portion 216 (the inner wall surface of the notch portion 214, the joint surface of the base substrate 211 with the channel substrate 212, and the joint surface of the cover substrate 213 with the channel substrate 212) are provided with wettability. You may make it form the hydrophilic treatment layer which improves.

The other ends of the working electrode 242, the counter electrode 243 and the reference electrode 244 located on the other end side of the electrode chip 24 are arranged outside the substrate 21 and connected to the potentiostat via the connector 8 and cable 9 (see FIG. 2). 3 (see FIG. 1). The electrode tip 24 is detachably attached to the connector 8 .

When the sample liquid is supplied to the sample liquid supply port 231 of the electrochemical analysis chip 2, the sample liquid flows through the sample liquid channel 232 through the three electrode chip placement portions 216 (notches 214) by capillary action. and is introduced into each electrode tip placement portion 216 . The sample liquid introduced into the electrode tip placement portion 216 flows toward the opening side (first side surface 212a side) of the electrode tip placement portion 216 through the gap between the electrode tip placement portion 216 and the electrode tip 24 by capillary action. It flows and contacts the sensor portion 22 of the electrode tip 24 .

As shown in FIGS. 1 to 4, the electrochemical analysis chip 2 of the present embodiment has a plurality of electrodes 242, 243, 244 and a sensor portion 22 provided on an insulating base material 21, and a base material 21 and a channel portion 23 provided in the sensor portion 22 for guiding the sample liquid to the sensor portion 22 . A plurality of sensor units 22 are provided on the substrate 21, and the flow path unit 23 supplies the sample liquid supply port 231 opened to the outer surface of the substrate 21 and the same sample liquid from the sample liquid supply port 231 to the plurality of sensors. and a sample liquid channel 232 leading to the portion 22 .

According to the electrochemical analysis chip 2, the same sample liquid can be led from the sample liquid supply port 231 to the plurality of sensor sections 22 by the sample liquid flow path 232. Therefore, the same sample liquid can be supplied to the plurality of sensor sections 22 by one sampling operation. The same sample liquid can be brought into contact. As a result, even with a very small amount of sample liquid, it is possible to measure a plurality of items with a single sampling operation.

In the electrochemical analysis chip 2 , the channel section 23 includes a plurality of sample liquid channels 232 connected to one sample liquid supply port 231 . As a result, the sample liquid can be introduced into the plurality of sensor units 22 simply by bringing the sample liquid into contact with one sample liquid supply port 231, so that the sampling operation is easy and the time required for the sampling operation can be shortened. .

In the electrochemical analysis chip 2 , the sensor section 22 is provided on an electrode chip 24 that can be attached to the substrate 21 . The base material 21 has an electrode tip placement portion 216 that opens to the outer surface of the base material 21 and into which the electrode tip 24 is inserted. A sample liquid flow path 232 is connected to the electrode chip placement section 216 , and the sample liquid flows from the sample liquid flow path 232 to the electrode chip placement section 216 by capillary action between the inner wall of the electrode chip placement section 216 and the electrode chip 24 . There is a gap that penetrates towards the opening of the As a result, by exchanging the electrode tip 24 according to the measurement item, it is possible to cope with a large number of measurement items, so that the versatility of the electrochemical analysis chip 2 is improved.

Next, the electrodes of the electrode tip 24 having the sensor section 22 will be described with reference to FIGS. 5 and 6 as well. At least one surface of the substrate 241 of the electrode tip 24 is made of a flat insulating material. The substrate 241 is, for example, a polyethylene terephthalate film, a polyimide film, a glass substrate, an epoxy glass (glass epoxy) substrate, or the like. However, the material of the substrate 241 is not limited to these, and may be ceramics, quartz glass, or the like.

In the electrode tip 24, each of the working electrode 242, the counter electrode 243 and the reference electrode 244 comprises a metal layer 251 formed on the substrate 241, a carbon layer 252 formed on the substrate 241 covering the metal layer 251, It comprises a lower adhesion layer 253 formed between the substrate 241 and the metal layer 251 and an upper adhesion layer 254 formed between the top surface of the metal layer 251 and the carbon layer 252 . A silver-silver chloride layer 255 is formed on the upper surface of the carbon layer 252 on one end side of the reference electrode 244 .

The lower adhesive layer 253 is a thin film that prevents separation between the substrate 241 and the metal layer 251, and is made of silicon, for example. As the material of the lower adhesive layer 253, any material having good adhesion to the substrate 241 and the metal layer 251 can be used, and in addition to silicon, for example, chromium, titanium (metal that covalently bonds with carbon), etc. can be used.

The metal layer 251 is made of a material with a lower electrical resistivity than the carbon layer 252 and is formed on the lower adhesion layer 253 . The metal layer 251 is for reducing electrical resistance between one end and the other end of each of the working electrode 242 , the counter electrode 243 and the reference electrode 244 . Materials for the metal layer 251 include, for example, silver, ruthenium, tantalum, titanium, copper, aluminum, platinum, niobium, zirconium, alloys of these elements, and alloys of these elements and carbon.

The upper adhesive layer 254 is formed on the upper surface of the metal layer 251, is a thin film that prevents separation between the upper surface of the metal layer 251 and the carbon layer 252, and is made of silicon.

A carbon layer 252 is formed on the substrate 241 to cover the lower adhesion layer 253 , the metal layer 251 and the upper adhesion layer 254 . The carbon layer 252 is made of amorphous carbon or diamond-like carbon (DLC), for example. In addition, the carbon layer 252 is formed so as to surround the contours of the lower adhesion layer 253 , the metal layer 251 and the upper adhesion layer 254 in plan view, and the bottom peripheral edge of the carbon layer 252 is in contact with the substrate 241 . The lower adhesion layer 253 , the metal layer 251 and the upper adhesion layer 254 are isolated from the ambient atmosphere by being surrounded by the substrate 241 and the carbon layer 252 .

Carbon is suitable for use in the carbon layer 252 that protects the metal layer 251 because it has the following properties. (1) excellent stability even in vacuum at 3000°C (in air at 500°C), (2) resistance to chemicals, (3) impermeability to gases and solutions, (4) excellent hardness, (5) excellent electrical conductivity; (6) resistance to wetting by metal salts; (7) good blood and tissue compatibility; (8) physical and chemical properties is isotropic.

As a method for manufacturing the lower adhesive layer 253, the metal layer 251, the upper adhesive layer 254, and the carbon layer 252, vapor deposition is preferable because the shape and film thickness of each layer can be controlled with high precision. Here, as the vapor deposition method, a so-called physical vapor deposition method (PVD) such as a vacuum deposition method, an ion plating method, a sputtering method, or a so-called chemical vapor deposition method (CVD) can be used. However, the method for manufacturing each layer is not limited to the vapor deposition method, and may be a printing method such as a screen printing method or an inkjet printing method.

In this embodiment, the electrodes 242 , 243 , 244 are composed of a metal layer 251 formed on an insulating substrate 241 , a carbon layer 252 formed on the substrate 241 covering the metal layer 251 , and the substrate 241 . and a lower adhesion layer 253 formed between the metal layer 251 . The electrodes 242, 243, and 244 have the metal layer 251 to lower the electrical resistance and improve the measurement sensitivity. In addition, by covering the metal layer 251 with the carbon layer 252, oxidation-reduction of the metal layer 251 can be prevented, and measurement sensitivity and reproducibility can be improved. Furthermore, by providing an upper adhesion layer 254 made of silicon between the upper surface of the metal layer 251 and the carbon layer 252, the adhesion between the metal layer 251 and the carbon layer 252 is improved, and silicon is more electrically conductive than metal. Since the resistivity is high, generation of hydrogen on the upper surface of the metal layer 251 can be suppressed during measurement. As a result, separation between the substrate 241 and the metal layer 251 can be prevented, and measurement sensitivity and reproducibility can be improved.

In addition, since the electrodes 242, 243, and 244 are provided with a lower adhesive layer 253 formed between the substrate 241 and the metal layer 251, deterioration of adhesion between the substrate 241 and the metal layer 251 during measurement can be prevented. can improve measurement sensitivity and reproducibility.

The metal layer 251, the carbon layer 252, and the adhesive layers 253 and 254 are formed by a vapor deposition method. The layer 252 is formed so as to surround the contours of the metal layer 251 and the adhesive layers 253 and 254 in plan view. By forming each layer 251, 252, 253, 254 by vapor deposition, the shape and film thickness of each layer 251, 252, 253, 254 can be controlled with high accuracy, and the overall electrical It can improve resistance stability.

Also, the lower adhesive layer 253 is made of silicon. Since silicon has good adhesion to glass and good adhesion to metal, the adhesion between the metal layer 251 and the substrate 241 can be strengthened. The upper adhesive layer 254 is also made of silicon. Since silicon has good adhesion to metal and good adhesion to carbon, the adhesion between the metal layer 251 and the carbon layer 252 can be strengthened.

Since the sensor section 22 includes a working electrode 242, a reference electrode 244, and a counter electrode 243, it can be applied to three-electrode electrochemical measurements. Further, the electrical resistance of the working electrode 242, the reference electrode 244, and the counter electrode 243 can be lowered, the oxidation-reduction of the metal layer 251 can be prevented, and the peeling of the metal layer 251 can be prevented, so that the measurement sensitivity and reproducibility can be improved. .

Note that the sensor section 22 may include two electrodes used in a two-electrode electrochemical measurement using the working electrode 242 and the reference electrode 244 . Then, if both the working electrode and the reference electrode are composed of electrodes having a metal layer, a carbon layer and an adhesion layer, the electrical resistance of both the working electrode and the reference electrode can be lowered, and the metal layer can be oxidized. Since reduction can be prevented and peeling of the metal layer can be prevented, measurement sensitivity and reproducibility can be improved.

The working electrode 242, the counter electrode 243, and the reference electrode 244 of the sensor unit 22 are not limited to the above structures, and may be, for example, a single-layer structure made of a metal material such as silver, platinum, gold, aluminum, or palladium, or a conductive material such as carbon. It may be a single-layer structure of a flexible material, or a laminated structure in which a plurality of these materials are laminated. Also, the electrodes 242 , 243 , 244 may not have the lower adhesive layer 253 .

As shown in FIG. 1, the potentiostat 3 controls the potential of the working electrode 242 of the electrode tip 24 to be constant with respect to the reference electrode 244, and controls the current flowing between the working electrode 242 and the counter electrode 243. configured to be measurable. The potentiostat 3 has an arithmetic control section 31, a voltage application section 32 and a current detection section 33 as a schematic configuration.

The arithmetic control unit 31 performs predetermined arithmetic processing using the measured values obtained by the electrochemical measurement, and performs necessary operations for the voltage application unit 32 based on commands from the user input via the operation unit 4. It is a function of transmitting signals and displaying information such as measurement results on the display unit 5 . The arithmetic control unit 31 is implemented by, for example, a microcomputer executing a predetermined program.

When the voltage application unit 32 receives a measurement start signal from the arithmetic control unit 31, the voltage application unit 32 applies a voltage having a desired waveform between the working electrode 242 and the counter electrode 243 of the electrode tip 24 to It is configured to control the potential between the reference electrode 244 to a desired potential.

The current detector 33 is configured to detect the magnitude of current flowing between the working electrode 242 and the counter electrode 243 of the electrode tip 24 . A signal relating to the magnitude of the current detected by the current detection unit 33 is taken into the arithmetic control unit 31 .

The arithmetic control unit 31 calculates the concentration of a specific component in the sample solution based on the signal received from the current detection unit 33, for example, using a calibration curve prepared in advance, and displays the measurement result on the display unit 5. is configured as

In the electrochemical measurement device 1 , the operation unit 4 is an input device for the user to perform operations such as turning on/off the power, starting measurement, and changing information displayed on the display unit 5 . The display unit 5 is implemented by, for example, a liquid crystal display. Note that the display unit 5 may be configured by a touch panel so that the display unit 5 also has the function of the operation unit 4 . The power supply unit 6 can be realized by, for example, a dry battery or a storage battery. Necessary electric power is supplied to the potentiostat 3 and the display unit 5 by the power supply unit 6 .

The potentiostat 3 is also connected to an external output unit 7 so that information can be output to an external device such as a personal computer by wired communication means such as a USB (Universal Serial Bus) terminal or wireless communication means. may In that case, the arithmetic control section 31 is configured to output measurement data and the like to the external device via the external output section 7 .

Note that the operation unit 4, the display unit 5, the power supply unit 6, and the external output unit 7 may be realized by a mobile computer such as a notebook computer or a tablet, for example. Furthermore, if a small potentiostat (for example, a small potentiostat "miniSTAT100" manufactured by Bio Device Technology) is used as the potentiostat 3, the electrochemical measurement apparatus 1 can be configured to be portable. This enables on-site (field) measurement of the sample liquid using the electrochemical measurement device 1 .

Electrochemical measurement using the electrochemical measurement device 1 is performed in a state in which the sample liquid is in contact with the sensor section 22 of the electrochemical analysis chip 2 . That is, the measurement is performed in a state in which the sample liquid is brought into contact with the sample liquid supply port 231 of the electrochemical analysis chip 2 and introduced into the sample liquid flow path 232 and the electrode chip arrangement portion 216 .

Next, an example of manufacturing the electrode tip 24 will be described. On a glass substrate having a thickness of about 2500 nm (2.5 μm) as the substrate 241, a silicon layer having a thickness of about 20 nm is formed by sputtering using a metal mask having an opening pattern corresponding to the lower adhesive layer forming region. It is formed as an adhesive layer 253 . The film thickness of the lower adhesive layer 253 made of silicon is not particularly limited.

A silver layer having a thickness of about 150 nm is formed as the metal layer 251 on the lower adhesive layer 253 by a sputtering method using a metal mask having the same opening pattern as the opening pattern corresponding to the lower adhesive layer forming region of the metal mask. did.

After that, using a metal mask having the same opening pattern as the opening pattern corresponding to the lower adhesive layer forming region, a silicon layer having a thickness of about 20 nm was formed as the upper adhesive layer 254 on the metal layer 251 by sputtering. The film thickness of the upper adhesive layer 254 made of silicon is not particularly limited.

Here, after the substrate 241 is carried into the chamber of the sputtering apparatus, the same metal mask is used to form the lower adhesive layer 253, the metal layer 251, and the upper adhesive layer 254 on the substrate 241 without carrying it out of the chamber. did. As a result, the time required for forming the lower adhesive layer 253, the metal layer 251, and the upper adhesive layer 254 can be shortened, and foreign matter can be prevented from adhering between the layers. Also, the metal layer 251 and the adhesive layers 253 and 254 are formed to have the same shape in plan view.

The line width of the lower adhesive layer 253, the metal layer 251 and the upper adhesive layer 254 (the dimension in the width direction perpendicular to the longitudinal direction) is about 0.6 mm.

A carbon layer 252 having a thickness of about 1000 nm is formed by a sputtering method using a metal mask having an opening pattern surrounding the lower adhesive layer forming region so as to cover the lower adhesive layer 253, the metal layer 251 and the upper adhesive layer 254. did. The line width of the carbon layer 252 is about 1 mm. This formed a working electrode 242, a counter electrode 243 and a reference electrode 244 having a lower adhesion layer 253, a metal layer 251, an upper adhesion layer 254 and a carbon layer 252, respectively.

In this way, the lower adhesive layer 253, the metal layer 251, the upper adhesive layer 254, and the carbon layer 252 are formed by a vapor deposition method (here, a sputtering method) using a metal mask having an opening pattern. Since patterning by an etching method or a lift-off method is not required after film formation, manufacturing costs can be reduced.

A silver layer having a thickness of about 100 nm was formed on the upper surface of the carbon layer 252 on one end side of the reference electrode 244 by a film forming method, and a silver-silver chloride layer 255 was formed by chlorination. Thus, the electrode tip 24 was produced.

In each electrode 242 , 243 , 244 of the electrode chip 24 , the side surface of the metal layer 251 is in contact with the carbon layer 252 . However, since the film thickness of the metal layer 251 is as thin as 150 nm, even if hydrogen is generated on the side surface of the metal layer 251, the amount of hydrogen is very small, and the measurement is difficult. The impact is considered to be small.

Although the film thickness of the metal layer 251 is not particularly limited, it is preferably 50 nm or more and 1000 nm or less. This is because within this range, the resistance value of the entire electrodes 242, 243, and 244 can be reduced while suppressing the amount of hydrogen generated on the side surface of the metal layer 251 to a small amount. If the film thickness of the metal layer 251 is less than 50 nm, the electrodes 242, 243, and 244 will have high resistance and the measurement sensitivity will decrease. Moreover, when the film thickness of the metal layer 251 is thicker than 1000 nm, the influence of hydrogen generated on the side surface of the metal layer 251 on the measurement becomes large. In particular, when the metal layer 251 is formed by a vapor deposition method (for example, a sputtering method), if the thickness of the metal layer 251 is greater than 1000 nm, the time required for forming the metal layer 251 increases, and the production efficiency decreases. descend.

The manufacturing cost can be reduced by providing regions for a plurality of electrode tips 24 on a single substrate 241, forming the plurality of electrode tips 24 at the same time, and then dividing the electrode tips 24 into individual pieces.

Next, an example of measurement using the electrode tip 24 will be described. A 100 ppm lead standard solution (Wako Pure Chemical Industries, Ltd.) diluted with distilled water to 1000 ppb (=1 ppm) was used as a sample. As a comparative example of the electrode chip 24, a metal layer 251 and a carbon layer 252 were formed on the substrate 241 without forming the adhesive layers 253 and 254 on the electrode chip 24, which was used as a comparative chip.

As the potentiostat 3, a small potentiostat "miniSTAT100" (manufactured by Bio Device Technology) was used. Electrochemical measurements were performed by differential pulse voltammetry (DPV). DPV measurement was performed by changing the potential of the working electrode from -1500 mV to 300 mV, with a potential increase of 0.004 V, a pulse amplitude of 0.05 V, a pulse duration of 0.2 seconds, and a sweep rate of 0.02 V/s. About 20 μL of each of the above samples was dropped on the electrode tip 24 and the comparative tip, and the measurement was performed. The resulting current-potential curves are shown in FIG. In FIG. 7, the vertical axis represents current and the horizontal axis represents potential.

As can be seen from FIG. 7, a good Pb peak was obtained in the measurement using the electrode tip 24 of the embodiment (see solid line A). On the other hand, in the measurement using the comparative chip (see broken line B), it was confirmed that the Pb peak was smaller and the Ag peak was larger than in the embodiment.

FIG. 8 is a micrograph of the electrode tip 24 after measurement and the working electrode 242 of the comparative tip taken from the substrate 241 side, (A) showing the embodiment (electrode tip 24), and (B) showing the comparative example ( comparison chip).

As can be seen from FIG. 8, peeling of the metal layer 251 was observed in the comparative chip (B), but peeling of the metal layer and the lower adhesive layer 253 was not observed in the electrode chip of the embodiment (A).

Thus, it was confirmed that by providing the lower adhesive layer 253 between the substrate 241 and the metal layer 251, separation between the substrate 241 and the metal layer 251 can be prevented, and measurement sensitivity and reproducibility can be improved.

In the electrode tip 24, as shown in FIG. 9, an upper adhesive layer 254 made of silicon may be formed so as to cover the side surfaces of the metal layer 251 as well. Such upper adhesive layer 254 can be formed by a vapor deposition method (eg, a sputtering method). This eliminates the contact area between the metal layer 251 and the carbon layer 252. Even if water permeates the carbon layer 252, generation of hydrogen on the surface of the metal layer 251 during measurement can be prevented. Adhesion of the carbon layer 252 can be improved. Thereby, peeling of the carbon layer 252 can be prevented more reliably.

Next, another embodiment of the electrochemical analysis chip will be described with reference to FIG. FIG. 10 is a plan view showing another embodiment of the electrochemical analysis chip. 10, illustration of the cover substrate 213 is omitted.

In the electrochemical analysis chip 2</b>A of this embodiment, the channel section 23 includes a sample liquid supply port 231 and a sample liquid channel 232 for each of the plurality of sensor sections 22 . That is, the three grooves 215 formed on one surface of the channel substrate 212A are provided separately from each other. The three sample liquid supply ports 231 formed by one ends of the three grooves 215 are arranged close to each other on the outer surface of the base material 21A (the second side surface 212b of the channel substrate 212A).

According to the electrochemical analysis chip 2</b>A, by providing the sample liquid supply port 231 and the sample liquid flow path 232 for each sensor section 22 , the sample liquid can be reliably introduced to each sensor section 22 . In addition, since the sample liquid supply ports 231 provided for each sensor unit 22 are arranged close to each other on the outer surface of the substrate 21A, the sample liquid can be reliably supplied to the sample liquid supply ports 231 by one sampling operation. They can be brought into contact with each other, and the certainty of the sampling process can be improved.

Next, still another embodiment of the electrochemical analysis chip will be described with reference to FIGS. 11 and 12. FIG. FIG. 11 is a plan view showing still another embodiment of the electrochemical analysis chip. FIG. 12 is an exploded perspective view of the same electrochemical analysis chip. Note that illustration of the cover substrate 213B is omitted in FIG.

In the electrochemical analysis chip 2B of this embodiment, the substrate 21B includes a base substrate 211B on which the sensor section 22 is formed, a flow path substrate 212B forming the flow path section 23, and a cover substrate 213B covering the flow path substrate 212B. are laminated.

Each sensor unit 22 is formed by one end of a working electrode 242, a counter electrode 243 and a reference electrode 244 having the same configuration as the electrodes 242, 243, 244 of the electrode chip 24 provided in the electrochemical analysis chip 2 of the above embodiment. there is The other end sides of the electrodes 242, 243, and 244 are arranged on a connector connecting portion 217 projecting from one side portion of the base substrate 211B.

In place of the notch 214 (see FIGS. 2 and 3, etc.) provided in the electrochemical analysis chip 2 of the above-described embodiment, the channel substrate 212B is formed with a sample liquid storage portion 218 composed of a through hole. there is The sample liquid storage section 218 is formed at a position surrounding the sensor section 22 in a state in which the base substrate 211B and the channel substrate 212B are superimposed.

Further, in the channel substrate 212B, a channel portion 23 for forming a sample liquid supply port 231 and a sample liquid channel 232 is formed in the same manner as in the electrochemical analysis chip 2 of the above-described embodiment. The end of the sample liquid channel 232 opposite to the sample liquid supply port 231 is connected to the sample liquid storage section 218 .

An air hole 219 is formed in a cover substrate 213B that is joined to the channel substrate 212B at a position that overlaps the sample liquid storage section 218 in plan view.

When the sample liquid is supplied to the sample liquid supply port 231 of the electrochemical analysis chip 2B by the sampling operation, the sample liquid flows through the sample liquid channel 232 toward each of the three sample liquid storage sections 218 by capillary action. , and is introduced into each sample liquid storage section 218 and comes into contact with each sensor section 22 . Thus, the electrochemical analysis chip 2B can bring the same sample liquid into contact with a plurality of sensor units 22 in one sampling operation.

According to such an aspect, by integrating the plurality of sensor units 22 with the base substrate 211B, the size of the electrochemical analysis chip 2B can be reduced. The configuration in which the sensor section 22 is integrated with the base substrate 211B can also be applied to a configuration in which the sample liquid supply port 231 and the sample liquid flow path 232 are provided for each sensor section 22 (see FIG. 10).

The present invention is not limited to the above-described embodiments, and can be embodied in various aspects. For example, the electrochemical analysis chip may have a configuration in which the working electrode 242 and the reference electrode 244 are provided as electrodes and the counter electrode 243 is not provided, and may be applicable to two-electrode electrochemical measurement.

In addition, the position where the sample liquid supply port is arranged is not limited to the side surface of the substrate constituting the electrochemical analysis chip, and the sample liquid supply port is located on one plane of the substrate (for example, the channel substrate of the base substrate 211). 212, or the surface of the cover substrate 213 opposite to the channel substrate 212).

In addition, the electrochemical analysis chip of the present invention is not limited to differential pulse voltammetry (DPV), but can be used for linear sweep voltammetry (LSV), chronoamperemetry (CA), cyclic voltammetry (CV), short wave voltammetry (SWV), and the like. It is also applicable to methods.

2, 2A, 2B Electrochemical analysis chips 21, 21A, 21B Base material 22 Sensor part 23 Channel part 24 Electrode chip 211, 211A, 211B Base substrate 212, 212A, 212B Channel substrate 212b Second side surface (outer surface of base material example)
213, 213B cover substrate 216 electrode chip placement portion 231 sample liquid supply port 232 sample liquid channel 242 working electrode (an example of an electrode)
243 counter electrode (an example of an electrode)
244 reference electrode (an example of an electrode)

Claims (6)

An electrochemical analysis chip comprising a sensor section having a plurality of electrodes and provided on an insulating base material, and a channel section provided on the base material for guiding a sample liquid to the sensor section,
A plurality of the sensor units are provided on the base material,
The flow path section includes a sample liquid supply port that opens to the outer surface of the substrate, and a sample liquid flow path that guides the same sample liquid from the sample liquid supply port to a plurality of the sensor sections,
The sensor unit is provided on an electrode chip that can be attached to the base material,
The base material has an electrode tip placement portion that opens to the outer surface of the base material and into which the electrode tip is inserted,
The sample liquid flow path is connected to the electrode chip placement section, and the sample liquid flows from the sample liquid flow path to the electrode chip placement section by capillary action between the inner wall of the electrode chip placement section and the electrode chip. An electrochemical analysis chip having a gap that penetrates toward the opening of the electrochemical analysis chip. 2. The electrochemical analysis chip according to claim 1, wherein said channel section includes a plurality of said sample liquid channels connected to one said sample liquid supply port. the flow path section includes the sample liquid supply port and the sample liquid flow path for each of the plurality of sensor sections;
2. The electrochemical analysis chip according to claim 1, wherein said plurality of sample liquid supply ports are arranged close to each other on the outer surface of said base material. The sensor unit comprises a working electrode and a reference electrode as the electrodes, or comprises a working electrode, a reference electrode and a counter electrode,
The electrode comprises a metal layer formed on an insulating substrate, a carbon layer formed on the substrate to cover the metal layer, and formed between the upper surface of the metal layer and the carbon layer. and an upper adhesive layer;
4. The electrochemical analysis chip according to claim 1 , wherein said upper adhesive layer is made of silicon. An electrochemical analysis chip comprising a sensor section having a plurality of electrodes and provided on an insulating base material, and a channel section provided on the base material for guiding a sample liquid to the sensor section,
A plurality of the sensor units are provided on the base material,
The flow path section includes a sample liquid supply port that opens to the outer surface of the base material, and a sample liquid flow path that guides the same sample liquid from the sample liquid supply port to a plurality of the sensor sections,
The sensor unit comprises a working electrode and a reference electrode as the electrodes, or comprises a working electrode, a reference electrode and a counter electrode,
The electrodes include a metal layer formed on an insulating substrate, a carbon layer formed on the substrate to cover the metal layer, and formed between the upper surface of the metal layer and the carbon layer. and an upper adhesive layer;
The electrochemical analysis chip, wherein the upper adhesive layer is made of silicon. 6. The base material according to claim 5, wherein the base substrate is formed by laminating a base substrate on which the sensor section is formed, a flow path substrate forming the flow path section, and a cover substrate covering the flow path substrate. Electrochemical analysis chip as described.

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