Electrodes and electrode chips

Abstract

The present invention provides an electrode and an electrode chip that can improve the measurement sensitivity and reproducibility of electrochemical measurements. The electrode chip (2) comprises: a metal layer (41) formed on an insulating substrate (21); a carbon layer (42) formed on the metal layer (41); and an upper bonding layer (44) formed between the upper surface of the metal layer (41) and the carbon layer (42). The upper bonding layer (44) is formed of silicon. The side surface of the metal layer (41) is covered by an insulating layer (25).

Description

Technical Field

[0001] The invention relates to an electrode and an electrode chip. 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 residual pesticides (see, for example, Patent Document 1), etc. In particular, for the measurement of heavy metals such as cadmium, mercury, arsenic, cobalt, copper, zinc, and lead, it is very important to understand the amount of these heavy metals contained in water, soil, food, vegetables, rice, and drinking water before ingesting them into the body.

[0003] In electrochemical measurement, it is known that an electrode chip having electrodes formed on an insulating substrate can be used. In the electrode 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, some metal materials corrode due to oxidation-reduction reactions with moisture in the air or sample, which may reduce the measurement sensitivity and reproducibility. In addition, although carbon materials are not easily oxidized and reduced, their resistivity is higher than that of metal materials, so their sensitivity is poor when used as electrodes.

[0005] As a method for solving such a problem, there is known a method of stacking a carbon layer on a metal layer formed on an insulating substrate (see, for example, Patent Documents 2 to 4).

[0006] However, conventional electrodes have a problem in that water that penetrates the carbon layer generates hydrogen on the metal layer surface during measurement, causing separation of the metal layer and the carbon layer and damage to the carbon layer, thereby reducing measurement sensitivity and reproducibility.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 11-248668

[0010] Patent Document 2: Japanese Patent No. 5120453

[0011] Patent Document 3: Japanese Patent Application Publication No. 2013-190212

[0012] Patent Document 4: Japanese Patent Application Publication No. 2014-153280 Summary of the invention

[0013] Problems to be solved by the invention

[0014] The present invention has been made to improve the above-mentioned situation, and its object is to provide an electrode and an electrode chip that can improve the measurement sensitivity and reproducibility of electrochemical measurement of trace components in a liquid sample.

[0015] Solutions for solving problems

[0016] The electrode of the present invention comprises: a metal layer formed on an insulating substrate; a carbon layer formed on the metal layer; and an upper bonding layer formed between the upper surface of the metal layer and the carbon layer, wherein the upper bonding layer is formed of silicon and the side of the metal layer is covered by an insulating layer.

[0017] According to the electrode of the present invention, the resistance is reduced due to the presence of a metal layer, thereby improving the measurement sensitivity. In addition, by covering the upper surface of the metal layer with a carbon layer and covering the side of the metal layer with an insulating 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 bonding 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 metal layer and the carbon layer can be prevented from peeling off, thereby improving the measurement sensitivity and reproducibility. In addition, since the side of the metal layer is covered by the insulating layer, moisture will not reach the side, and the generation of hydrogen on the side of the metal layer can be prevented.

[0018] The electrode of the present invention may include a lower adhesive layer formed between the substrate and the metal layer.

[0019] According to such an embodiment, it is possible to prevent the adhesion between the substrate and the metal layer from being reduced during measurement, thereby improving the measurement sensitivity and reproducibility.

[0020] Preferably, the lower adhesive layer is formed of, for example, silicon, chromium, titanium, tungsten, or a surface treatment layer formed by performing a surface treatment on the surface of the substrate to improve the adhesion between the substrate and the metal layer. However, the lower adhesive layer may also be formed of metals other than the above.

[0021] The electrode chip of the present invention comprises a working electrode (working electrode) and a reference electrode (reference electrode) which are constituted by the electrode of the present invention.

[0022] The electrode chip according to the present invention can be applied to electrochemical measurements using a two-electrode method using a working electrode and a reference electrode. Furthermore, the working electrode and the reference electrode are both composed of the electrode of the present invention having a metal layer, a carbon layer, and an adhesive layer, so that the working electrode and the reference electrode can reduce resistance, prevent oxidation and reduction of the metal layer, and prevent peeling of the carbon layer, thereby improving measurement sensitivity and reproducibility.

[0023] The electrode chip of the present invention may further include a counter electrode composed of the electrode of the present invention.

[0024] According to such a scheme, it is applicable to electrochemical measurement using a three-electrode method using a working electrode, a reference electrode, and a counter electrode. In addition, since the working electrode, the reference electrode, and the counter electrode can reduce resistance, prevent oxidation and reduction of the metal layer, and prevent peeling of the carbon layer, the measurement sensitivity and reproducibility can be improved.

[0025] Effects of the Invention

[0026] The present invention can provide an electrode and an electrode chip capable of improving the measurement sensitivity and reproducibility of electrochemical measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram showing an example of an electrochemical measuring device.

[0028] Figure 2 This is a schematic plan view showing one embodiment of an electrode chip.

[0029] Figure 3 is with Figure 2 A schematic cross-sectional view corresponding to the A-A position.

[0030] Figure 4 It is a schematic cross-sectional view showing another embodiment of the electrode chip. DETAILED DESCRIPTION

[0031] Embodiments of the electrode and the electrode chip of the present invention will be described with reference to the drawings. Figure 1 It is a schematic configuration diagram showing this embodiment. Figure 2 It is a top view showing one embodiment of an electrode chip.

[0032] like Figure 1 As shown, the electrochemical measuring device 1 includes an electrode chip 2, a potentiostat 3 connected to the electrode 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 electrode chip 2 is a disposable electrode chip.

[0033] like Figure 2As shown, the electrode chip 2 has a flat insulating substrate 21, on which a working electrode 22, a counter electrode 23 and a reference electrode 24 are insulated from each other. The substrate 21 has a substantially rectangular shape when viewed from above. The working electrode 22, the counter electrode 23 and the reference electrode 24 are arranged in a manner extending from one end of the long dimension direction of the substrate 21 to the other end.

[0034] An insulating layer 25 is formed on the substrate 21 to insulate the working electrode 22, the counter electrode 23, and the reference electrode 24 from each other. The insulating layer 25 is embedded between the electrodes 22, 23, 24 and is provided to surround the contours of the electrodes 22, 23, 24, thereby covering the side surfaces of the electrodes 22, 23, 24.

[0035] In the electrode chip 2, a liquid sample 10 containing a substance to be measured is in contact with one end of a working electrode 22, a counter electrode 23, and a reference electrode 24. The other ends of the working electrode 22, the counter electrode 23, and the reference electrode 24 of the electrode chip 2 are connected to each other via a connector 8 and a cable 9 (omitted in FIG. Figure 1 The electrode chip 2 is electrically connected to the potentiostat 3. The electrode chip 2 is detachably mounted on the connector 8.

[0036] At least one surface of the substrate 21 of the electrode chip 2 is formed of a flat insulating material. The material of the substrate 21 is not particularly limited, and examples thereof include polyimide (PI), glass, polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyoxymethylene (POM), ABS (ABS (acrylonitrile-butadiene-styrene): acrylonitrile-butadiene-styrene), etc. However, the material of the substrate 21 is not limited to these, and may also be ceramic, quartz, etc. In addition, the shape, thickness, and size of the substrate 21 are not particularly limited.

[0037] like Figure 2 and Figure 3As shown, in the electrode chip 2, the working electrode 22, the counter electrode 23 and the reference electrode 24 respectively include: a metal layer 41 formed on the substrate 21; a carbon layer 42 formed to cover the metal layer 41; a lower adhesive layer 43 formed between the substrate 21 and the metal layer 41; and an upper adhesive layer 44 formed between the upper surface of the metal layer 41 and the carbon layer 42. A silver-silver chloride layer 45 is formed on the upper surface of the carbon layer 42 at one end of the reference electrode 24.

[0038] The lower adhesive layer 43 is a thin film, for example, made of silicon, which prevents the substrate 21 from peeling off from the metal layer 41. The material of the lower adhesive layer 43 can be any material that has good adhesion between the substrate 21 and the metal layer 41, and in addition to silicon, chromium, titanium, and tungsten can also be used.

[0039] In addition, the lower adhesive layer 43 may also be formed of a surface treatment layer formed by performing a surface treatment on the surface of the substrate 21 to improve the adhesion between the substrate 21 and the metal layer 41. Examples of such surface treatments include plasma treatment, corona treatment, flame treatment, etching treatment, steam treatment, and ion beam treatment.

[0040] The metal layer 41 is formed of a material having a lower resistivity than the carbon layer 42, and is formed on the lower adhesive layer 43. The metal layer 41 is a layer for reducing the resistance between one end and the other end of each of the working electrode 22, the counter electrode 23, and the reference electrode 24. As the material of the metal layer 41, 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.

[0041] The upper adhesive layer 44 is formed on the upper surface of the metal layer 41 , is a thin film for preventing the upper surface of the metal layer 41 and the carbon layer 42 from peeling off, and is formed of silicon.

[0042] The carbon layer 42 is formed on the metal layer 41 via the upper adhesive layer 44. The carbon layer 42 is formed of, for example, amorphous carbon or diamond-like carbon (DLC: diamond-like carbon).

[0043] Carbon is suitable for use as the carbon layer 42 for protecting the metal layer 41 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.

[0044] As a method for manufacturing the lower adhesive layer 43, the metal layer 41, the upper adhesive layer 44, and the carbon layer 42, a 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, a so-called physical vapor deposition method (PVD: physical vapor deposition) such as a vacuum vapor deposition method, an ion plating method, a sputtering method, or a 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.

[0045] like Figure 2 and Figure 3 As shown, the insulating layer 25 is formed to surround the lower adhesive layer 43, the metal layer 41, and the upper adhesive layer 44 in a plan view. The side surface of the metal layer 41 is covered by the insulating layer 25. In the present embodiment, the side surface of the lower adhesive layer 43, the side surface of the upper adhesive layer 44, and the side surface of the carbon layer 42 are also covered by the insulating layer 25. The lower surface of the insulating layer 25 is in contact with the substrate 21. The lower adhesive layer 43, the metal layer 41, and the upper adhesive layer 44 are isolated from the surrounding atmosphere by being surrounded by the substrate 21 and the insulating layer 25.

[0046] The material of the insulating layer 25 is not particularly limited, and examples thereof include silicon oxide film (SiO2), silicon nitride film (Si3N4), aluminum oxide (Al2O3), etc. However, the insulating layer 25 is not limited to a layer formed of these materials, as long as it can isolate the side surfaces of the electrodes 22, 23, and 24 (at least the side surfaces of the metal layer 41) from the surrounding atmosphere and prevent moisture from passing through.

[0047] It should be noted that the height position (thickness) of the upper surface of the insulating layer 25 only needs to be such that the insulating layer 25 can at least cover the side surface of the metal layer 41. In order to increase the contact area between the insulating layer 25 and the carbon layer 42, it is preferred that the height position of the upper surface of the insulating layer 25 is the same as the height position of the upper surface of the carbon layer 42. In this way, it is possible to reliably prevent moisture from penetrating from between the insulating layer 25 and the carbon layer 42 into the metal layer 41.

[0048] In this embodiment, the electrodes 22, 23, and 24 include: a metal layer 41 formed on an insulating substrate 21; a carbon layer 42 formed on the substrate 21 so as to cover the metal layer 41; and a lower adhesive layer 43 formed between the substrate 21 and the metal layer 41. The electrodes 22, 23, and 24 have a metal layer 41, and the resistance is reduced, thereby improving the measurement sensitivity. In addition, by covering the upper surface of the metal layer 41 with the carbon layer 42 and covering the side of the metal layer 41 with the insulating layer 25, the oxidation and reduction of the metal layer 41 can be prevented, and the measurement sensitivity and reproducibility can be improved. In addition, by providing the upper adhesive layer 44 formed of silicon between the upper surface of the metal layer 41 and the carbon layer 42, the adhesion between the metal layer 41 and the carbon layer 42 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 41 during measurement can be suppressed. Furthermore, since the side surfaces of the metal layer 41 are covered by the insulating layer 25, moisture does not reach the side surfaces, and generation of hydrogen can be prevented on the side surfaces of the metal layer 41. Thus, separation of the substrate 21 and the metal layer 41 can be prevented, and measurement sensitivity and reproducibility can be improved.

[0049] Furthermore, since the electrodes 22, 23, and 24 include the lower adhesive layer 43 formed between the substrate 21 and the metal layer 41, it is possible to prevent the adhesion between the substrate 21 and the metal layer 41 from decreasing during measurement, thereby improving measurement sensitivity and reproducibility.

[0050] In addition, the metal layer 41, the carbon layer 42, and the adhesive layers 43, 44 are formed by the vapor deposition method, and the metal layer 41, the carbon layer 42, and the adhesive layers 43, 44 are formed in the same shape when viewed from above. By forming each layer 41, 42, 43, 44 by the vapor deposition method, the shape and film thickness of each layer 41, 42, 43, 44 can be controlled with high precision, and the overall resistance stability can be improved for each of the electrodes 22, 23, 24.

[0051] In addition, the lower adhesive layer 43 is formed of silicon. Silicon has good adhesion to glass and metal, so it can enhance the adhesion between the metal layer 41 and the substrate 21. In addition, the upper adhesive layer 44 is also formed of silicon. Silicon has good adhesion to metal and carbon, so it can enhance the adhesion between the metal layer 41 and the carbon layer 42.

[0052] The electrode chip 2 includes a working electrode 22, a reference electrode 24, and a counter electrode 23, and is therefore applicable to electrochemical measurements using a three-electrode method. Furthermore, the working electrode 22, the reference electrode 24, and the counter electrode 23 can reduce resistance, prevent oxidation and reduction of the metal layer 41, and prevent peeling of the metal layer 41, thereby improving measurement sensitivity and reproducibility.

[0053] It should be noted that the electrode chip according to the present invention can be applied to electrochemical determination using a two-electrode method of a working electrode and a reference electrode. In addition, the working electrode and the reference electrode are both composed of the electrode of the present invention having a metal layer, a carbon layer and an adhesive layer. Therefore, with respect to the working electrode and the reference electrode, since the resistance can be reduced, the oxidation-reduction of the metal layer can be prevented, and the peeling of the metal layer can be prevented, the measurement sensitivity and reproducibility can be improved.

[0054] like Figure 1 As shown, the potentiostat 3 is configured to control the potential of the working electrode 22 of the electrode chip 2 to be constant relative to the reference electrode 24, and can measure the current flowing between the working electrode 22 and the counter electrode 23. As a general structure, the potentiostat 3 includes a calculation control unit 31, a voltage application unit 32 and a current detection unit 33.

[0055] The calculation control unit 31 performs a predetermined calculation process using the measurement value obtained by the electrochemical measurement, and based on the instruction from the user input through the operation unit 4, sends a signal required by the voltage application unit 32 or displays information such as the measurement result on the display unit 5. The calculation control unit 31 is realized by, for example, a microcomputer executing a predetermined program.

[0056] The voltage application unit 32 is configured to apply a voltage of a desired waveform between the working electrode 22 and the counter electrode 23 of the electrode chip 2 when receiving a measurement start signal from the operation control unit 31, so as to control the potential between the working electrode 22 and the reference electrode 24 to become the desired potential.

[0057] The current detection unit 33 is configured to detect the magnitude of the current flowing between the working electrode 22 and the counter electrode 23 of the electrode chip 2. A signal related to the magnitude of the current detected by the current detection unit 33 is input to the calculation control unit 31.

[0058] 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 .

[0059] 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.

[0060] 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 unit such as a USB (universal serial bus) terminal or a wireless communication unit. 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.

[0061] 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 potentiostat (such as a small potentiostat "miniSTAT100" (manufactured by BioDevice Technology)) is used as the potentiostat 3, the electrochemical measuring device 1 can be configured to be portable. Thus, the measurement of a liquid sample on-site using the electrochemical measuring device 1 can be performed.

[0062] like Figure 2 As shown, electrochemical measurement using the electrochemical measurement device 1 is performed in a state where the liquid sample 10 is dropped on the electrode chip 2. The liquid sample 10 is dropped onto the substrate 21 in a manner of contacting the working electrode 22, the counter electrode 23, and the reference electrode 24 relative to the electrode chip 2. It should be noted that the measurement may also be performed in a state where one end side of the working electrode 22, the counter electrode 23, and the reference electrode 24 is immersed in the liquid sample.

[0063] Next, an example of manufacturing the electrode chip 2 is described. On a glass substrate having a thickness of about 2500 nm (2.5 μm) as the substrate 21, a silicon layer having a thickness of about 20 nm is formed as the lower adhesive layer 43 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 43 formed of silicon is not particularly limited.

[0064] A silver layer having a thickness of about 150 nm is formed as the metal layer 41 on the lower adhesive layer 43 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.

[0065] 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 41 as the upper adhesive layer 44. It should be noted that the film thickness of the upper adhesive layer 44 formed of silicon is not particularly limited.

[0066] Next, using a metal mask having the same opening pattern as that corresponding to the lower adhesive layer formation region, a carbon layer 42 having a thickness of about 1000 nm is formed by sputtering on the upper adhesive layer 44. In this way, the working electrode 22, the counter electrode 23, and the reference electrode 24 each having the lower adhesive layer 43, the metal layer 41, the upper adhesive layer 44, and the carbon layer 42 are formed.

[0067] Here, after the substrate 21 is moved into the chamber of the sputtering device, the lower adhesive layer 43, the metal layer 41, the upper adhesive layer 44, and the carbon layer 42 are formed on the substrate 21 using the same metal mask without being moved out of the chamber. Thus, the time required for forming the lower adhesive layer 43, the metal layer 41, the upper adhesive layer 44, and the carbon layer 42 can be shortened, and foreign matter can be prevented from adhering to the layers. In addition, the metal layer 41, the carbon layer 42, and the adhesive layers 43 and 44 are formed in the same shape when viewed from above.

[0068] The line width (dimension in the width direction perpendicular to the longitudinal direction) of the electrodes 22, 23, and 24 is about 1.0 mm. The interval between the electrodes 22, 23, and 24 is about 0.5 mm.

[0069] By sputtering, using a metal mask having an opening pattern opened around the lower bonding layer formation area, an insulating layer 25 having a thickness of about 1200 nm is formed on the substrate 21 so as to cover the lower bonding layer 43, the metal layer 41, the upper bonding layer 44, and the side surfaces of the carbon layer 42 (the side surfaces of the electrodes 22, 23, 24). The insulating layer 25 is formed so as to surround the electrodes 22, 23, 24 and be buried between the electrodes 22, 23, 24.

[0070] In this way, a lower bonding layer 43, a metal layer 41, an upper bonding layer 44, a carbon layer 42 and an insulating layer 25 are formed by a vapor deposition method (here, a sputtering method) using a metal mask having an opening pattern. Thus, after each layer is formed, there is no need to perform patterning by an etching method or a stripping method, thereby reducing manufacturing costs.

[0071] On the upper surface of the carbon layer 42 at one end of the reference electrode 24, 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 45. In this way, the electrode chip 2 is manufactured. It should be noted that the silver-silver chloride layer 45 can be formed after the insulating layer 25 is formed, or it can be formed before the insulating layer 25 is formed.

[0072] The thickness of the metal layer 41 is not particularly limited, but is preferably 50 nm or more and 1000 nm or less. It should be noted that when the thickness of the metal layer 41 is thinner than 50 nm, the electrodes 22, 23, and 24 become high resistance, and the measurement sensitivity is reduced. In addition, when the thickness of the metal layer 41 is thicker than 1000 nm, when the metal layer 41 is formed by a vapor deposition method (such as a sputtering method), the time required for forming the metal layer 41 becomes longer, and the production efficiency is reduced.

[0073] It should be noted that after a region for a plurality of electrode chips 2 is provided on one substrate 21 and a plurality of electrode chips 2 are formed simultaneously, each electrode chip 2 is separated into individual pieces, thereby reducing the manufacturing cost.

[0074] In the electrode chip 2, it can also be, for example Figure 4 As shown, a surface treatment layer 46 formed by performing a surface treatment to improve adhesion is formed on the surface of the substrate 21 as a lower adhesive layer, and the metal layer 41 and the insulating layer 25 are formed on the surface treatment layer 46. As a result, the adhesion between the substrate 21 and the metal layer 41 and the insulating layer 25 can be improved, the intrusion of moisture from between the substrate 21 and the insulating layer 25 can be reliably prevented, and the generation of hydrogen on the side of the metal layer 41 and the peeling of the insulating layer 25 during measurement can be more reliably prevented.

[0075] The present invention is not limited to the above-mentioned embodiment, and can be embodied in various forms. For example, the electrode chip may have a configuration that does not include the counter electrode 23 but includes the working electrode 22 and the reference electrode 24 as electrodes and is applicable to electrochemical measurement using a two-electrode method.

[0076] In addition, the electrode 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).

[0077] Description of Reference Numerals

[0078] 1: Electrochemical measurement device;

[0079] 2: Electrode chip;

[0080] 3: Constant potential instrument;

[0081] 4: Operation part;

[0082] 5: Display unit;

[0083] 6: Power supply;

[0084] 7: External output unit;

[0085] 8: Connector;

[0086] 9: Cable;

[0087] 10: Liquid sample;

[0088] 21: Substrate;

[0089] 22: working electrode;

[0090] 23: counter electrode;

[0091] 24: reference electrode;

[0092] 25: insulation layer;

[0093] 31: operation control unit;

[0094] 32: voltage applying unit;

[0095] 33: current detection unit;

[0096] 41: metal layer;

[0097] 42: Carbon layer;

[0098] 43: lower bonding layer;

[0099] 44: upper bonding layer;

[0100] 45: silver-silver chloride layer;

[0101] 46: Surface treatment layer.

Claims

1. An electrode comprising: A metal layer is formed on an insulating substrate; a carbon layer formed on the metal layer; and an upper bonding layer formed between the upper surface of the metal layer and the carbon layer, The upper bonding layer is formed of silicon, The side surfaces of the metal layer are covered by an insulating layer.

2. The electrode according to claim 1, comprising: A lower adhesive layer is formed between the substrate and the metal layer.

3. The electrode according to claim 2, wherein The lower adhesive layer is formed of silicon, chromium, titanium, tungsten, or a surface treatment layer formed by subjecting the surface of the substrate to a surface treatment that improves adhesion between the substrate and the metal layer.

4. An electrode chip, comprising: The working electrode and the reference electrode are composed of the electrodes according to any one of claims 1 to 3.

5. The electrode chip according to claim 4, further comprising: The counter electrode is composed of the electrode according to any one of claims 1 to 3.

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