Electrochemical analysis chip

Abstract

The present invention provides an electrochemical analysis chip capable of measuring multiple items by sampling once. The electrochemical analysis chip (2) comprises a sensor unit (22) and a flow path unit (23), wherein the sensor unit (22) has multiple electrodes (242, 243, 244) and is disposed on an insulating substrate (21), and the flow path unit (23) is disposed on the substrate (21) and guides a sample liquid to the sensor unit (22). Multiple sensor units (22) are disposed on the substrate (21). The flow path unit (23) comprises: a sample liquid supply port (231) opening on the outer surface of the substrate (21); and a sample liquid flow path (232) guiding the same sample liquid from the sample liquid supply port (231) to multiple sensor units (22).

Description

Technical Field

[0001] The present invention relates to an electrochemical analysis chip for measuring the concentration of a specific substance that may be contained in a sample liquid. Background Art

[0002] Measurements based on the principle of electrochemical measurement are used in many scenarios: high-sensitivity measurement of heavy metals in solutions, glucose measurement using enzyme electrodes, pH (hydrogen ion concentration index) measurement using ion electrodes, food inspection represented by electrochemical detection of pesticide residues (for example, see Patent Document 1), etc.

[0003] In electrochemical measurement, it is known that an electrochemical analysis chip having electrodes formed on an insulating substrate can be used. In the electrochemical analysis chip, the electrodes are basically single-layer structures, and metal materials such as silver, platinum, gold, and aluminum or conductive materials such as carbon are used as electrode materials.

[0004] However, when using the conventional electrochemical analysis chip to simultaneously measure multiple items, it is necessary to perform sampling operations for each of the multiple items. However, if sampling operations are performed for each of the multiple items, there will be the following problems: uneven concentration (the concentration will vary depending on the location of the sample specimen, the sampling site, whether it is initial or intermediate, etc.), and the measurement accuracy and reproducibility will be reduced. In addition, if the same sample solution is sampled multiple times, a large amount of sample solution will be required.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 11-248668 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The present invention has been made to improve the above-mentioned situation, and its object is to provide an electrochemical analysis chip capable of performing measurements of multiple items through a single sampling operation.

[0010] Solutions for solving problems

[0011] The electrochemical analysis chip of the present invention is an electrochemical analysis chip comprising a sensor portion and a flow path portion, wherein the sensor portion has a plurality of electrodes and is disposed on an insulating substrate, and the flow path portion is disposed on the substrate and guides a sample liquid to the sensor portion. In the electrochemical analysis chip, a plurality of the sensor portions are disposed on the substrate, and the flow path portion comprises a sample liquid supply port and a sample liquid flow path, wherein the sample liquid supply port opens on an outer surface of the substrate, and the sample liquid flow path guides the same sample liquid from the sample liquid supply port to the plurality of sensor portions.

[0012] According to the electrochemical analysis chip of the present invention, the same sample liquid can be guided from the sample liquid supply port to multiple sensor parts through the sample liquid flow path, so that the same sample liquid can be brought into contact with multiple sensor parts through one sampling operation. Thus, even a trace amount of sample liquid can be measured for multiple items through one sampling operation.

[0013] In the electrochemical analysis chip of the present invention, the flow path section may include a plurality of the sample solution flow paths connected to one sample solution supply port.

[0014] According to such a configuration, the sample liquid can be introduced into a plurality of sensor portions simply by bringing the sample liquid into contact with one sample liquid supply port. Therefore, the sampling operation is easy and the time required for the sampling operation can be shortened.

[0015] In the electrochemical analysis chip of the present invention, the flow path section may include the sample solution supply port and the sample solution flow path for each of the plurality of sensor sections, and the plurality of sample solution supply ports may be disposed close to each other on the outer surface of the substrate.

[0016] According to such a scheme, by providing a sample liquid supply port and a sample liquid flow path for each sensor part, the sample liquid can be reliably introduced into each sensor part. In addition, by arranging the sample liquid supply ports provided for each sensor part close to each other on the outer surface of the substrate, the sample liquid can be reliably brought into contact with these sample liquid supply ports through a single sampling operation, thereby improving the reliability of the sampling process.

[0017] In the electrochemical analysis chip of the present invention, it can also be arranged that the sensor part is arranged on an electrode chip that can be attached to the substrate, the substrate has an electrode chip configuration part, the electrode chip configuration part has an opening on the outer surface of the substrate for the electrode chip to be inserted, the sample liquid flow path is connected to the electrode chip configuration part, and a gap is provided between the inner wall of the electrode chip configuration part and the electrode chip, and the gap is used for the sample liquid to penetrate from the sample liquid flow path toward the opening of the electrode chip configuration part by capillary phenomenon.

[0018] According to such a configuration, it is possible to cope with many measurement items by replacing the electrode chip according to the measurement items, and thus the versatility is improved.

[0019] In the electrochemical analysis chip of the present invention, the substrate may be configured by laminating a base substrate on which the sensor portion is formed, a flow path substrate on which the flow path portion is formed, and a cover substrate covering the flow path substrate.

[0020] According to such an embodiment, the electrochemical analysis chip can be miniaturized by integrating the sensor unit and the base substrate.

[0021] In the electrochemical analysis chip of the present invention, it can also be set that the sensor part has a working electrode and a reference electrode or has a working electrode, a reference electrode and a counter electrode as the electrode, and the electrode has a metal layer formed on an insulating substrate, a carbon layer formed on the substrate in a manner covering the metal layer, and an upper bonding layer formed between the upper surface of the metal layer and the carbon layer, and the upper bonding layer is formed of silicon.

[0022] According to such a scheme, each electrode has a metal layer, so that the resistance is reduced, thereby improving the measurement sensitivity. In addition, by covering the metal layer with a carbon layer, the oxidation-reduction of the metal layer can be prevented, and the measurement sensitivity and reproducibility can be improved. Moreover, by providing an upper adhesive layer formed 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 since silicon has a higher resistivity than metal, the generation of hydrogen on the upper surface of the metal layer during measurement can be suppressed, and the peeling of the metal layer and the carbon layer can be prevented, thereby improving the measurement sensitivity and reproducibility.

[0023] Effects of the Invention

[0024] The present invention can provide an electrochemical analysis chip capable of measuring multiple items through one sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram showing an example of an electrochemical measuring device.

[0026] Figure 2 It is a top view showing one embodiment of the electrochemical analysis chip.

[0027] Figure 3 This is an isolated stereogram of the electrochemical analysis chip.

[0028] Figure 4 It is a side view of the central longitudinal section of the electrochemical analysis chip.

[0029] Figure 5 It is a schematic plan view showing an electrode chip.

[0030] Figure 6 is with Figure 5 A schematic cross-sectional view corresponding to the A-A position.

[0031] Figure 7 This is a graph showing current potential curves obtained using the electrode chip mounted in the embodiment and a comparative chip.

[0032] Figure 8 This is a microscope photograph of the working electrodes of the electrode chip and the comparison chip after the measurement, taken from the substrate side. Figure 8 (A) represents an embodiment (electrode chip), Figure 8 (B) shows a comparative example (comparative chip).

[0033] Fig. 9 It is a schematic cross-sectional view showing another structure of the electrode chip.

[0034] Fig.10 It is a top view showing another embodiment of the electrochemical analysis chip.

[0035] Fig.11 It is a top view showing still another embodiment of the electrochemical analysis chip.

[0036] Fig.12 This is an isolated stereogram of the electrochemical analysis chip. DETAILED DESCRIPTION

[0037] Embodiments of the electrochemical analysis chip will be described based on the drawings. Figure 1 This is a schematic diagram showing an example of an electrochemical measuring device. Figure 2 It is a top view showing one embodiment of the electrochemical analysis chip. Figure 3 This is an isolated stereogram of the electrochemical analysis chip. Figure 4 is a side view of the central longitudinal section of the electrochemical analysis chip. Figure 2 In FIG. 2 , the cover substrate 213 is omitted. Figure 4 In the figure, for convenience, the thickness of each component is enlarged for illustration.

[0038] like Figure 1 As shown, the 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. In this embodiment, the electrochemical analysis chip 2 is a disposable electrochemical analysis chip.

[0039] like Figure 2 to Figure 4 As shown, the electrochemical analysis chip 2 includes: an insulating substrate 21; a plurality of sensor portions 22 provided on the substrate 21; and a flow path portion 23 provided on the substrate 21 and guiding the sample liquid to each sensor portion 22. In the present embodiment, three sensor portions 22 are provided, but in the electrochemical analysis chip of the present invention, the number of sensor portions may be two or four or more.

[0040] The substrate 21 is configured by placing a cover substrate 213 on a base substrate 211 via a flow path substrate 212. The base substrate 211, the flow path substrate 212, and the cover substrate 213 are configured by substantially quadrilateral insulating substrates.

[0041] The flow path substrate 212 is formed with a cutout 214 into which the electrode chip 24 having the sensor unit 22 can be inserted and a groove 215 for forming a sample liquid supply port 231 and a sample liquid flow path 232 constituting the flow path unit 23. In this embodiment, three cutouts 214 are formed.

[0042] The cutout 214 opens at the first side surface 212a of the flow channel substrate 212 and is formed with a width slightly larger than the width of the electrode chip 24. The cutout 214 is covered by the base substrate 211 and the cover substrate 213, thereby forming an electrode chip placement portion 216.

[0043] The groove 215 is formed on one surface of the flow path substrate 212, extending from the second side surface 212b opposite to the first side surface 212a of the flow path substrate 212 toward the first side surface 212a, and branching into three in the middle, and connected to the three notch portions 214. The groove 215 is covered by the cover substrate 213, thereby forming a flow path portion 23 having a sample liquid supply port 231 and a sample liquid flow path 232, the sample liquid supply port 231 opening on the outer surface of the substrate 21 (the second side surface 212b of the flow path substrate 212), and the sample liquid flow path 232 guiding the same sample liquid from the sample liquid supply port 231 to the plurality of sensor portions 22.

[0044] The material of the insulating substrate constituting the base substrate 211, the flow path substrate 212 and the cover substrate 213 is not particularly limited, and examples thereof include glass, quartz glass, polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyoxymethylene (POM), ABS resin (ABS (acrylonitrile-butadiene-styrene), acrylonitrile-butadiene-styrene), polymethyl methacrylate resin (PMMA: polymethyl methacrylate), etc. In addition, the shape, thickness and size of the insulating substrate are not particularly limited.

[0045] The dimensions of the sample liquid supply port 231 and the sample liquid flow path 232 may be any dimensions as long as the sample liquid can be introduced from the sample liquid supply port 231 to the sample liquid flow path 232 by a capillary phenomenon and thus guided to the sensor portion 22. In addition, a hydrophilic treatment layer that improves wettability may be formed on the inner wall surface of the sample liquid flow path 232 (the inner wall surface of the groove 215 and the bonding surface of the cover substrate 213 with the flow path substrate 212).

[0046] like Figure 3 and Figure 4 As shown, the substrate 21 of the electrochemical analysis chip 2 is formed by stacking and integrating a base substrate 211, a flow path substrate 212, and a cover substrate 213 in this order. For bonding the base substrate 211 and the flow path substrate 212, and bonding the flow path substrate 212 and the cover substrate 213, for example, an adhesive or thermal welding can be used.

[0047] The electrode chip 24 having the sensor part 22 is assembled on the electrode chip configuration part 216 of the substrate 21. The electrode chip 24 has a flat insulating substrate 241, and a working electrode 242, a counter electrode 243 and a reference electrode 244 are provided on the substrate 241 in an insulated manner. The substrate 241 has a substantially rectangular shape when viewed from above. The working electrode 242, the counter electrode 243 and the reference electrode 244 are arranged in a manner extending from near one end of the long dimension direction of the substrate 241 to near the other end. The middle part of the long dimension direction of the working electrode 242, the counter electrode 243 and the reference electrode 244 is covered by an insulating layer 245 formed on the substrate 241. One end side of the working electrode 242, the counter electrode 243 and the reference electrode 244 constitutes the sensor part 22.

[0048] One end of the electrode chip 24 is inserted into the electrode chip arrangement portion 216 of the substrate 21, whereby the sensor portion 22 (one end of the working electrode 242, the counter electrode 243, and the reference electrode 244) is arranged inside the electrode chip arrangement portion 216. A small gap is formed between the inner wall of the electrode chip arrangement portion 216 and the electrode chip 24, and the gap is such that the sample liquid introduced into the flow path portion 23 by the capillary phenomenon will penetrate into the opening side (the first side surface 212a side) of the electrode chip arrangement portion 216 by the capillary phenomenon.

[0049] It should be noted that the size of the gap between the inner wall of the electrode chip configuration part 216 and the electrode chip 24 is not particularly limited as long as the sample liquid can penetrate from the sample liquid flow path 232 toward the opening of the electrode chip configuration part 216 by capillary phenomenon. In addition, it can also be set that a hydrophilic treatment layer that improves wettability is formed on the inner wall surface of the electrode chip configuration part 216 (the inner wall surface of the notch 214, the bonding surface of the base substrate 211 with the flow path substrate 212, and the bonding surface of the cover substrate 213 with the flow path substrate 212).

[0050] The other ends of the working electrode 242, the counter electrode 243, and the reference electrode 244 located at the other end of the electrode chip 24 are arranged outside the substrate 21 and connected to the substrate 21 via the connector 8 and the cable 9 (see Figure 2 ) and potentiostat 3 (refer to Figure 1 The electrode chip 24 is detachably mounted on the connector 8.

[0051] When the sample liquid is supplied to the sample liquid supply port 231 of the electrochemical analysis chip 2, the sample liquid flows toward the three electrode chip arrangement parts 216 (notch parts 214) in the sample liquid flow path 232 by the capillary phenomenon and is introduced into each electrode chip arrangement part 216. The sample liquid introduced into the electrode chip arrangement part 216 flows toward the opening side (first side surface 212a side) of the electrode chip arrangement part 216 in the gap between the electrode chip arrangement part 216 and the electrode chip 24 by the capillary phenomenon and contacts the sensor part 22 of the electrode chip 24.

[0052] like Figure 1 to Figure 4 As shown, the electrochemical analysis chip 2 of this embodiment includes: a sensor portion 22 having a plurality of electrodes 242, 243, 244 and provided on an insulating substrate 21; and a flow path portion 23 provided on the substrate 21 and guiding a sample liquid to the sensor portion 22. The substrate 21 is provided with a plurality of sensor portions 22, and the flow path portion 23 includes: a sample liquid supply port 231 opened on the outer surface of the substrate 21; and a sample liquid flow path 232 guiding the same sample liquid from the sample liquid supply port 231 to the plurality of sensor portions 22.

[0053] According to the electrochemical analysis chip 2, the same sample liquid can be guided from the sample liquid supply port 231 to the plurality of sensor portions 22 via the sample liquid flow path 232. Therefore, the same sample liquid can be brought into contact with the plurality of sensor portions 22 by a single sampling operation. Thus, even a trace amount of sample liquid can be measured by a single sampling operation for a plurality of items.

[0054] In the electrochemical analysis chip 2, the flow path section 23 includes a plurality of sample liquid flow paths 232 connected to one sample liquid supply port 231. Thus, the sample liquid can be introduced into the plurality of sensor sections 22 simply by bringing the sample liquid into contact with one sample liquid supply port 231, thereby facilitating the sampling operation and shortening the time required for the sampling operation.

[0055] In the electrochemical analysis chip 2, the sensor section 22 is provided on an electrode chip 24 that can be attached to a substrate 21. The substrate 21 includes an electrode chip placement section 216 that is opened on the outer surface of the substrate 21 for inserting the electrode chip 24. The sample liquid flow path 232 is connected to the electrode chip placement section 216, and a gap is provided between the inner wall of the electrode chip placement section 216 and the electrode chip 24, and the sample liquid permeates from the sample liquid flow path 232 toward the opening of the electrode chip placement section 216 by a capillary phenomenon. Thus, it is possible to cope with many measurement items by replacing the electrode chip 24 according to the measurement items, and thus the versatility of the electrochemical analysis chip 2 is improved.

[0056] Next, refer to Figure 5 and Figure 6 , the electrode of the electrode chip 24 having the sensor part 22 is described. At least one surface of the substrate 241 of the electrode chip 24 is formed of a flat insulating material. As the substrate 241, for example, a polyethylene terephthalate film, a polyimide film, a glass substrate, an epoxy glass (glass epoxy: glass epoxy) substrate, etc. However, the material of the substrate 241 is not limited to these, and it can also be ceramics, quartz glass, etc.

[0057] In the electrode chip 24, the working electrode 242, the counter electrode 243, and the reference electrode 244 respectively include a metal layer 251 formed on a substrate 241, a carbon layer 252 formed on the substrate 241 so as to cover the metal layer 251, a lower adhesive layer 253 formed between the substrate 241 and the metal layer 251, and an upper adhesive layer 254 formed between the upper 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 at one end of the reference electrode 244.

[0058] The lower adhesive layer 253 is a thin film that prevents the substrate 241 and the metal layer 251 from peeling off, and is formed of, for example, silicon. The material of the lower adhesive layer 253 can be any material that has good adhesion between the substrate 241 and the metal layer 251. In addition to silicon, for example, chromium, titanium (a metal covalently bonded to carbon), etc. can also be used.

[0059] The metal layer 251 is formed of a material having a lower resistivity than the carbon layer 252, and is formed on the lower adhesive layer 253. The metal layer 251 is a layer for reducing the resistance between one end and the other end of each of the working electrode 242, the counter electrode 243, and the reference electrode 244. As the material of the metal layer 251, for example, silver, ruthenium, tantalum, titanium, copper, aluminum, platinum, niobium, zirconium, or alloys of these elements, or alloys of these elements and carbon, etc. can be used.

[0060] The upper adhesive layer 254 is formed on the upper surface of the metal layer 251 , is a thin film for preventing the upper surface of the metal layer 251 and the carbon layer 252 from peeling off, and is formed of silicon.

[0061] The carbon layer 252 is formed on the substrate 241 in a manner covering the lower adhesive layer 253, the metal layer 251, and the upper adhesive layer 254. The carbon layer 252 is formed of, for example, amorphous carbon or diamond-like carbon (DLC). In addition, the carbon layer 252 is formed to surround the lower adhesive layer 253, the metal layer 251, and the upper adhesive layer 254 in a top view, and the lower surface peripheral portion of the carbon layer 252 is in contact with the substrate 241. The lower adhesive layer 253, the metal layer 251, and the upper adhesive layer 254 are isolated from the surrounding atmosphere by being surrounded by the substrate 241 and the carbon layer 252.

[0062] Carbon is suitable for use as the carbon layer 252 for protecting the metal layer 251 because it has the following properties: (1) It has excellent stability even in a vacuum at 3000°C (500°C in air); (2) It is not easily corroded by chemicals; (3) It is impermeable to gases and solutions; (4) It has excellent hardness and strength; (5) It has excellent electrical conductivity; (6) It has resistance to wetting by metal salts, etc.; (7) It has good blood and tissue compatibility; and (8) It has isotropy in physical and chemical properties.

[0063] As a method for manufacturing the lower adhesive layer 253, the metal layer 251, the upper adhesive layer 254, and the carbon layer 252, the vapor deposition method is preferred from the viewpoint of being able to control the shape and film thickness of each layer with high precision. Here, as the vapor deposition method, the so-called physical vapor deposition method (PVD: physical vapor deposition) such as vacuum vapor deposition method, ion plating method, sputtering method, and so-called chemical vapor deposition method (CVD: chemical vapor deposition) can be used. However, the method for manufacturing each layer is not limited to the vapor deposition method, and a printing method such as a screen printing method and an inkjet printing method may also be used.

[0064] In this embodiment, the electrodes 242, 243, and 244 include a metal layer 251 formed on an insulating substrate 241, a carbon layer 252 formed on the substrate 241 so as to cover the metal layer 251, and a lower adhesive layer 253 formed between the substrate 241 and the metal layer 251. The electrodes 242, 243, and 244 have a metal layer 251, and the resistance is reduced, thereby improving the measurement sensitivity. In addition, by covering the metal layer 251 with the carbon layer 252, the oxidation-reduction of the metal layer 251 can be prevented, and the measurement sensitivity and reproducibility can be improved. In addition, by providing the upper adhesive layer 254 formed 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 since the resistivity of silicon is higher than that of metal, the generation of hydrogen on the upper surface of the metal layer 251 during measurement can be suppressed. As a result, the peeling of the substrate 241 and the metal layer 251 is prevented, thereby improving the measurement sensitivity and reproducibility.

[0065] Furthermore, since the electrodes 242, 243, and 244 include the lower adhesive layer 253 formed between the substrate 241 and the metal layer 251, a decrease in the adhesion between the substrate 241 and the metal layer 251 during measurement can be prevented, thereby improving measurement sensitivity and reproducibility.

[0066] Furthermore, the metal layer 251, the carbon layer 252, and the adhesive layers 253 and 254 are layers formed by a vapor deposition method, and the metal layer 251 and the adhesive layers 253 and 254 are formed in the same shape when viewed from above, and the carbon layer 252 is formed in a shape surrounding the metal layer 251 and the adhesive layers 253 and 254 when viewed from above. By forming each layer 251, 252, 253, and 254 by a vapor deposition method, the shape and film thickness of each layer 251, 252, 253, and 254 can be controlled with high precision, and the overall resistance stability can be improved for each of the electrodes 242, 243, and 244.

[0067] In addition, the lower adhesive layer 253 is formed of silicon. Since silicon has good adhesion to glass and metal, the adhesion between the metal layer 251 and the substrate 241 can be enhanced. In addition, the upper adhesive layer 254 is also formed of silicon. Since silicon has good adhesion to metal and carbon, the adhesion between the metal layer 251 and the carbon layer 252 can be enhanced.

[0068] The sensor unit 22 includes a working electrode 242, a reference electrode 244, and a counter electrode 243, and is therefore applicable to electrochemical measurements using a three-electrode method. Furthermore, the working electrode 242, the reference electrode 244, and the counter electrode 243 can reduce resistance, prevent oxidation and reduction of the metal layer 251, and prevent peeling of the metal layer 251, thereby improving measurement sensitivity and reproducibility.

[0069] It should be noted that the sensor unit 22 may be a sensor unit having two electrodes used in a two-electrode electrochemical measurement using a working electrode 242 and a reference electrode 244. Furthermore, if the working electrode and the reference electrode are both composed of electrodes having a metal layer, a carbon layer, and an adhesive layer, the resistance of the working electrode and the reference electrode can be reduced, oxidation-reduction of the metal layer can be prevented, and peeling of the metal layer can be prevented, thereby improving the measurement sensitivity and reproducibility.

[0070] In addition, the working electrode 242, the counter electrode 243, and the reference electrode 244 of the sensor unit 22 are not limited to the above-mentioned structures, and may be, for example, a single-layer structure of a metal material such as silver, platinum, gold, aluminum, palladium, or a single-layer structure of a conductive material such as carbon, or a stacked structure in which a plurality of these materials are stacked. In addition, the lower adhesive layer 253 may not be provided in the electrodes 242, 243, and 244.

[0071] like Figure 1 As shown, the potentiostat 3 is configured to control the potential of the working electrode 242 of the electrode chip 24 to be constant relative to the reference electrode 244, and can measure the current flowing between the working electrode 242 and the counter electrode 243. As a general structure, the potentiostat 3 includes a calculation control unit 31, a voltage application unit 32, and a current detection unit 33.

[0072] The calculation control unit 31 performs predetermined calculation processing using the measurement values ​​obtained by the electrochemical measurement, and based on the instructions from the user input through the operation unit 4, sends a signal required by the voltage application unit 32 or causes the display unit 5 to display information such as the measurement results. The calculation control unit 31 is implemented, for example, by a microcomputer executing a predetermined program.

[0073] The voltage application unit 32 is configured to apply a voltage of a desired waveform between the working electrode 242 and the counter electrode 243 of the electrode chip 24 when receiving a measurement start signal from the operation control unit 31, so as to control the potential between the working electrode 242 and the reference electrode 244 to become the desired potential.

[0074] The current detection unit 33 is configured to detect the magnitude of the current flowing between the working electrode 242 and the counter electrode 243 of the electrode chip 24. A signal related to the magnitude of the current detected by the current detection unit 33 is input to the calculation control unit 31.

[0075] The calculation control unit 31 is configured to calculate the concentration of a specific component in the sample solution based on the signal received from the current detection unit 33 using, for example, a calibration curve prepared in advance, and to display the measurement result on the display unit 5 .

[0076] In the electrochemical measuring device 1, the operating unit 4 is an input device for the user to perform operations such as turning on / off the power supply, starting the measurement, and changing the information displayed on the display unit 5. The display unit 5 is, for example, a liquid crystal display. It should be noted that the display unit 5 may also be formed of a touch panel so that the display unit 5 also has the function of the operating unit 4. The power supply unit 6 may be implemented by, for example, a dry cell, a storage battery, etc. The power supply unit 6 supplies the required power to the constant potential instrument 3 and the display unit 5.

[0077] In addition, the potentiostat 3 may be connected to an external output unit 7 so that information can be output to an external device such as a personal computer through a wired communication means such as a USB (universal serial bus) terminal or a wireless communication means. In this case, the calculation control unit 31 is configured to output measurement data and the like to the external device through the external output unit 7.

[0078] It should be noted that the operation unit 4, the display unit 5, the power supply unit 6, and the external output unit 7 may be implemented by a mobile computer such as a notebook computer or a tablet computer. Furthermore, if a small constant potential meter (such as a small constant potential meter "miniSTAT100" (manufactured by BioDevice Technology)) is used as the constant potential meter 3, the electrochemical measuring device 1 can be configured to be portable. Thus, the measurement of the sample solution on-site using the electrochemical measuring device 1 can be performed.

[0079] The electrochemical measurement using the electrochemical measurement device 1 is performed in a state where 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 where the sample liquid is in contact with the sample liquid supply port 231 of the electrochemical analysis chip 2 and the sample liquid is introduced into the sample liquid flow path 232 and the electrode chip arrangement section 216.

[0080] Next, an example of manufacturing the electrode chip 24 is 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 as the lower adhesive layer 253 by sputtering using a metal mask having an opening pattern corresponding to the lower adhesive layer formation region. It should be noted that the film thickness of the lower adhesive layer 253 formed of silicon is not particularly limited.

[0081] A silver layer having a thickness of about 150 nm is formed as the metal layer 251 on the lower adhesive layer 253 by sputtering using a metal mask having an opening pattern identical to the opening pattern of the metal mask corresponding to the lower adhesive layer forming region.

[0082] Then, using a metal mask having the same opening pattern as that corresponding to the lower adhesive layer formation region, a silicon layer with a thickness of about 20 nm is formed by sputtering on the metal layer 251 as the upper adhesive layer 254. It should be noted that the film thickness of the upper adhesive layer 254 formed of silicon is not particularly limited.

[0083] Here, after the substrate 241 is moved into the chamber of the sputtering device, the lower adhesive layer 253, the metal layer 251, and the upper adhesive layer 254 are formed on the substrate 241 using the same metal mask without being moved out of the chamber. Thus, 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 to the layers. In addition, the metal layer 251 and the adhesive layers 253 and 254 are formed into the same shape when viewed from above.

[0084] The line width (dimension in the width direction perpendicular to the longitudinal direction) of the lower adhesive layer 253 , the metal layer 251 , and the upper adhesive layer 254 is about 0.6 mm.

[0085] By sputtering, a carbon layer 252 having a thickness of about 1000 nm is formed using a metal mask having an opening pattern surrounding the lower adhesive layer formation region so as to cover the lower adhesive layer 253, the metal layer 251, and the upper adhesive layer 254. The line width of the carbon layer 252 is about 1 mm. Thus, the working electrode 242, the counter electrode 243, and the reference electrode 244 each having the lower adhesive layer 253, the metal layer 251, the upper adhesive layer 254, and the carbon layer 252 are formed.

[0086] In this way, a lower bonding layer 253, a metal layer 251, an upper bonding layer 254 and a carbon layer 252 are formed by a vapor deposition method (here, a sputtering method) using a metal mask having an opening pattern. Thus, after the formation of each layer, there is no need to perform patterning by an etching method or a stripping method, thereby reducing manufacturing costs.

[0087] On the upper surface of the carbon layer 252 at one end of the reference electrode 244, a silver layer having a thickness of about 100 nm is formed by a film forming method and then subjected to chlorination treatment to form a silver-silver chloride layer 255. In this way, the electrode chip 24 is manufactured.

[0088] In each electrode 242, 243, 244 of the electrode chip 24, the side of the metal layer 251 is in contact with the carbon layer 252. Although it can be considered that during electrochemical measurement, hydrogen will be generated on the side of the metal layer 251 due to water infiltrating the carbon layer 252, since the film thickness of the metal layer 251 is very thin at 150nm, it can be considered that even if it is assumed that hydrogen is generated on the side of the metal layer 251, the amount of hydrogen is extremely small and the impact on the measurement is very small.

[0089] The film thickness of the metal layer 251 is not particularly limited, but is preferably greater than 50nm and less than 1000nm. This is because when it is within this range, the amount of hydrogen generated on the side of the metal layer 251 can be suppressed to a small amount while reducing the overall resistance value of the electrodes 242, 243, and 244. It should be noted that when the film thickness of the metal layer 251 is thinner than 50nm, the electrodes 242, 243, and 244 become high resistance and the measurement sensitivity is reduced. In addition, when the film thickness of the metal layer 251 is thicker than 1000nm, the influence of the hydrogen generated on the side of the metal layer 251 on the measurement becomes greater. In particular, when the metal layer 251 is formed into a film by a vapor deposition method (such as a sputtering method), when the film thickness of the metal layer 251 is thicker than 1000nm, the time required for the film formation of the metal layer 251 becomes longer, and the production efficiency is reduced.

[0090] It should be noted that after a region for a plurality of electrode chips 24 is provided on one substrate 241 and a plurality of electrode chips 24 are formed simultaneously, each electrode chip 24 is separated into individual pieces, thereby reducing the manufacturing cost.

[0091] Next, a measurement example using the electrode chip 24 is described. A solution prepared by diluting a 100 ppm lead standard solution (Wako Pure Chemical Industries, Ltd.) with distilled water to a concentration of 1000 ppb (= 1 ppm) was used as a sample. As a comparative example of the electrode chip 24, the following electrode chip was prepared for use as a comparative chip: With respect to the electrode chip 24, a metal layer 251 and a carbon layer 252 were formed on a substrate 241 in such a manner that adhesive layers 253 and 254 were not formed.

[0092] A small potentiostat "miniSTAT100" (manufactured by BioDevice Technology) was used as the potentiostat 3. Electrochemical measurements were performed by differential pulse voltammetry (DPV). The measurement by DPV was performed by changing the potential of the working electrode from -1500 mV to 300 mV and by increasing the potential by 0.004 V, pulse amplitude by 0.05 V, pulse duration by 0.2 seconds, and scanning speed by 0.02 V / s. About 20 μL of the above sample was dripped onto the electrode chip 24 and the comparison chip, respectively, for measurement. The resulting current potential curve is shown in Figure 7 .exist Figure 7 In the figure, the vertical axis represents the current and the horizontal axis represents the potential.

[0093] from Figure 7 It can be seen that a good Pb peak was obtained in the measurement using the electrode chip 24 of the embodiment (see solid line A). In contrast, it was confirmed that the Pb peak was smaller and the Ag peak was larger in the measurement using the comparative chip (see dotted line B) compared with the embodiment.

[0094] Figure 8 This is a microscope photograph of the electrode chip 24 and the working electrode 242 of the comparison chip after the measurement, taken from the substrate 241 side. Figure 8 (A) represents an embodiment (electrode chip 24), Figure 8 (B) shows a comparative example (comparative chip).

[0095] from Figure 8 It is known that in Figure 8 In the comparative chip (B), the peeling of the metal layer 251 was observed, but in Figure 8 In the electrode chip of the embodiment (A), no separation between the metal layer and the lower adhesive layer 253 was observed.

[0096] In this way, it was confirmed that by providing the lower adhesive layer 253 between the substrate 241 and the metal layer 251 , separation of the substrate 241 and the metal layer 251 can be prevented, thereby improving measurement sensitivity and reproducibility.

[0097] In the electrode chip 24, it is also possible to Fig. 9 As shown in the figure, the upper adhesive layer 254 formed of silicon also covers the side of the metal layer 251. Such an upper adhesive layer 254 can be formed by a vapor deposition method (for example, a sputtering method). As a result, the area where the metal layer 251 and the carbon layer 252 are in contact disappears, and even if water penetrates into the carbon layer 252, the generation of hydrogen on the surface of the metal layer 251 during measurement can be prevented, and the adhesion between the metal layer 251 and the carbon layer 252 can be improved. As a result, the peeling of the carbon layer 252 can be more reliably prevented.

[0098] Next, refer to Fig.10 , other embodiments of the electrochemical analysis chip are described. Fig.10 FIG. 1 is a top view showing another embodiment of the electrochemical analysis chip. Fig.10 In the figure, the cover substrate 213 is omitted.

[0099] In the electrochemical analysis chip 2A of this embodiment, the flow path section 23 includes a sample liquid supply port 231 and a sample liquid flow path 232 for each of the plurality of sensor sections 22. That is, the three grooves 215 formed on one surface of the flow path substrate 212A are provided to be separated from each other. Furthermore, the three sample liquid supply ports 231 formed by one end of the three grooves 215 are arranged close to each other on the outer surface of the substrate 21A (the second side surface 212b of the flow path substrate 212A).

[0100] According to the electrochemical analysis chip 2A, by providing the sample liquid supply port 231 and the sample liquid flow path 232 for each sensor portion 22, the sample liquid can be reliably introduced into each sensor portion 22. In addition, by arranging the sample liquid supply port 231 provided for each sensor portion 22 close to each other on the outer surface of the substrate 21A, the sample liquid can be reliably brought into contact with these sample liquid supply ports 231 through a single sampling operation, and the reliability of the sampling process can be improved.

[0101] Next, refer to Fig.11 and Fig.12 , another embodiment of the electrochemical analysis chip is described. Fig.11 It is a top view showing still another embodiment of the electrochemical analysis chip. Fig.12 is a three-dimensional diagram of the electrochemical analysis chip. Fig.11 In the figure, the cover substrate 213B is omitted.

[0102] In the electrochemical analysis chip 2B of this embodiment, the substrate 21B is configured by laminating a base substrate 211B having the sensor unit 22 formed thereon, a flow path substrate 212B having the flow path unit 23 formed thereon, and a cover substrate 213B covering the flow path substrate 212B.

[0103] Each sensor unit 22 is formed at one end of a working electrode 242, a counter electrode 243, and a reference electrode 244. The working electrode 242, the counter electrode 243, and the reference electrode 244 have the same configuration as the electrodes 242, 243, and 244 of the electrode chip 24 of the electrochemical analysis chip 2 of the above-mentioned embodiment. The other end side of the electrodes 242, 243, and 244 is arranged on the connector connection part 217 protrudingly provided on one side of the base substrate 211B.

[0104] The flow channel substrate 212B is provided with a sample liquid storage portion 218 composed of a through hole instead of the notch portion 214 (see FIG. 2 ) provided in the electrochemical analysis chip 2 of the above embodiment. Figure 2 and Figure 3 The sample liquid storage section 218 is formed at a position surrounding the sensor section 22 in a state where the base substrate 211B and the flow channel substrate 212B are overlapped.

[0105] In addition, the flow path substrate 212B is provided with a flow path section 23 for forming a sample liquid supply port 231 and a sample liquid flow path 232, similarly to the electrochemical analysis chip 2 of the above embodiment. The end of the sample liquid flow path 232 opposite to the sample liquid supply port 231 is connected to the sample liquid storage section 218.

[0106] The cover substrate 213B bonded to the flow channel substrate 212B has an air hole 219 formed at a position overlapping with the sample solution storage section 218 in a plan view.

[0107] 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 toward the three sample liquid storage parts 218 in the sample liquid flow path 232 by the capillary phenomenon, is introduced into each sample liquid storage part 218, and contacts each sensor part 22. In this way, the electrochemical analysis chip 2B can contact the same sample liquid with multiple sensor parts 22 by one sampling operation.

[0108] According to such a scheme, the electrochemical analysis chip 2B can be miniaturized by integrating the plurality of sensor units 22 with the base substrate 211B. It should be noted that the structure in which the sensor unit 22 is integrated with the base substrate 211B can also be applied to the structure in which the sample liquid supply port 231 and the sample liquid flow path 232 are provided for each sensor unit 22 (see Fig.10 ).

[0109] The present invention is not limited to the above-mentioned embodiment, and can be embodied in various forms. For example, the electrochemical analysis chip may have a configuration that does not include the counter electrode 243 but includes the working electrode 242 and the reference electrode 244 as electrodes and is applicable to electrochemical measurement using a two-electrode method.

[0110] In addition, the position at which the sample liquid supply port is configured is not limited to the side of the substrate constituting the electrochemical analysis chip, and the sample liquid supply port can also be configured on a plane of the substrate (for example, the surface of the base substrate 211 on the opposite side of the flow path substrate 212 or the surface of the cover substrate 213 on the opposite side of the flow path substrate 212).

[0111] In addition, the electrochemical analysis chip of the present invention can also be applied to methods such as linear sweep voltammetry (LSV), chronoamperometry (CA), cyclic voltammetry (CV), short waveform voltammetry (SWV), etc., but is not limited to differential pulse voltammetry (DPV).

[0112] Description of Reference Numerals

[0113] 2. 2A, 2B: Electrochemical analysis chip;

[0114] 21, 21A, 21B: substrate;

[0115] 22: sensor unit;

[0116] 23: Flow path part;

[0117] 24: electrode chip;

[0118] 211, 211A, 211B: base substrate;

[0119] 212, 212A, 212B: flow path substrate;

[0120] 212b: second side (an example of an outer surface of the substrate);

[0121] 213, 213B: cover substrate;

[0122] 216: electrode chip configuration unit;

[0123] 231: sample liquid supply port;

[0124] 232: sample liquid flow path;

[0125] 242: working electrode (an example of an electrode);

[0126] 243: counter electrode (an example of an electrode);

[0127] 244: Reference electrode (an example of an electrode).

Claims

1. An electrochemical analysis chip comprising a sensor unit and a flow path unit, wherein the sensor unit has a plurality of electrodes and is provided on an insulating substrate, and the flow path unit is provided on the substrate and guides a sample liquid to the sensor unit, wherein: A plurality of sensor portions are provided on the substrate, The flow path unit includes: a sample liquid supply port opened on the outer surface of the substrate; and a sample liquid flow path for guiding the same sample liquid from the sample liquid supply port to the plurality of sensor units. The sensor part is provided on an electrode chip which can be attached to the substrate. The substrate includes an electrode chip placement portion, the electrode chip placement portion is opened on the outer surface of the substrate for inserting the electrode chip, The sample liquid flow path is connected to the electrode chip placement part, and a gap is provided between the inner wall of the electrode chip placement part and the electrode chip, through which the sample liquid permeates from the sample liquid flow path toward the opening of the electrode chip placement part by capillary phenomenon.

2. The electrochemical analysis chip according to claim 1, wherein: The flow path section includes a plurality of the sample liquid flow paths connected to one sample liquid supply port.

3. The electrochemical analysis chip according to claim 1, wherein: The flow path section includes the sample liquid supply port and the sample liquid flow path for each of the plurality of sensor sections. The plurality of sample liquid supply ports are disposed close to each other on the outer surface of the substrate.

4. The electrochemical analysis chip according to any one of claims 1 to 3, wherein: The substrate is configured by laminating a base substrate on which the sensor portion is formed, a flow path substrate on which the flow path portion is formed, and a cover substrate covering the flow path substrate.

5. The electrochemical analysis chip according to any one of claims 1 to 3, wherein: The sensor unit includes a working electrode and a reference electrode or includes a working electrode, a reference electrode and a counter electrode as the electrodes. The electrode comprises a metal layer formed on an insulating substrate, a carbon layer formed on the substrate so as to cover the metal layer, and an upper adhesive layer formed between an upper surface of the metal layer and the carbon layer. The upper adhesive layer is formed of silicon.

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