Four-electrode coplanar standard electrode with self-calibration function and application thereof

Abstract

This invention provides a four-electrode coplanar standard electrode with self-calibration function and its application. Specifically, four electrodes are coplanarly modified on the same plane of the electrode substrate, including a working electrode, a reference electrode and two auxiliary electrodes. The working electrode serves as a test electrode, with a detection layer (6) at the upper end and an interdigitated strip at the middle end. The auxiliary electrode serves as a calibration electrode, with an interdigitated strip parallel and equidistant to the aforementioned one at the upper end, thereby constructing an interdigitated electrode structure between the working electrode and the calibration electrode to form a calibration area (7). The upper end of the reference electrode extends vertically to form a first end, which together with the calibration area (7) constitutes a calibration electrolytic cell (9). The upper end of the reference electrode extends upward to form a second end, which together with the detection layer (6) and the upper end of the first electrode constitutes a working electrolytic cell (8).

Description

Technical Field

[0001] This invention belongs to the field of electrochemical interdigitated electrodes and relates to a four-electrode coplanar standard electrode with self-calibration function and its application. Background Technology

[0002] In recent years, with the rapid development of Industry 4.0 and the Internet of Things, emerging industries and other sectors have increasingly demanded sensors. Electrodes, as one of the core components of sensors, have received more and more attention from society. How to improve the detection performance of electrodes is directly related to the technical level of various sensors, which has become a common problem in the electronics and information industry.

[0003] Electrodes are the most important sensitive components of electrochemical sensors. Generally, sensors require two or more electrodes, with three-electrode systems being the most widely used. A three-electrode system consists of a working electrode, a reference electrode, and a counter electrode. However, in traditional three-electrode systems, the three electrodes are not integrated on a single plane; the electrodes are relatively far apart. During electrochemical testing, concentration polarization can easily occur between the working and counter electrodes, affecting the accuracy of the measurement. Furthermore, traditional three-electrode systems are large in size, which is inconvenient for the design and fabrication of miniature sensors, limiting the application of three-electrode systems.

[0004] Patent CN201920553197.X discloses a portable three-electrode structure, specifically integrating the working electrode, counter electrode, and reference electrode onto the same plane, significantly reducing the size of the three electrodes and facilitating the design and fabrication of micro-sensors. However, the surface of the fixed-area disk-shaped working electrode requires sufficient coating of the test solution to achieve stable monitoring, making it unsuitable for situations with limited test solution.

[0005] Patent CN202121826688.0 discloses a four-electrode integrated dual-working-electrode standard electrode, specifically integrating two working electrodes on the same plane. It can be used with a dual potentiostat to simultaneously detect two different substances in complex systems, or to detect specific substances and their intermediates, or to detect redox reactions. However, the stability and sensitivity of the electrode still require a certain volume of the test solution to cover the surface of the working electrodes, making it unsuitable for situations with small amounts of test solution.

[0006] However, none of the electrodes mentioned above can confirm their accuracy before the initial test. Electrode testing is required to confirm their accuracy before formal testing. Furthermore, they cannot be modified with metal plating on the corresponding electrode surface according to the requirements of the test target. In other words, they lack self-calibration and secondary modification functions, which causes some inconvenience in the actual use of the electrodes. Summary of the Invention

[0007] In view of this, the present invention provides a four-electrode coplanar standard electrode with self-calibration function and its application.

[0008] The purpose of this invention is to provide a four-electrode coplanar standard electrode with self-calibration function, including an electrode substrate. Specifically, four coplanar electrodes are fixedly disposed on the electrode substrate, which are, from left to right, a first electrode (1), a second electrode (2), a third electrode (3), and a fourth electrode (4). The four electrodes include a lead portion and a detection portion. The lead portions of the four electrodes are equidistantly disposed at one end of the standard electrode, namely the first lead, the second lead, the third lead, and the fourth lead. The detection portion of the four electrodes is disposed at the other end of the standard electrode and is connected to the lead portions of the four electrodes respectively, including a first detection portion, a second detection portion, a third detection portion, and a fourth detection portion. A detection layer (6) is connected to the upper end of the second detection portion. Several second interdigitated strips extend vertically from the middle of the second detection portion. Several third interdigitated strips extend vertically from the upper end of the third detection portion. The second interdigitated strips and the third interdigitated strips are arranged in a comb-like, equidistant, staggered manner to form an interdigitated structure, forming a calibration area (7). The second detection portion is located below the calibration area (7). The upper end of the fourth detection portion extends into a first end and a second end.

[0009] Furthermore, the total area of ​​the second interdigitated strip is one-quarter of the area of ​​the detection layer (6).

[0010] Furthermore, a working electrolytic cell (8) is provided on the electrode surface, including the area where the second end of the first detection section, the detection layer (6), and the fourth detection section are located; a calibration electrolytic cell (9) is provided on the electrode surface, including the area where the second detection section, the third detection section, the calibration area (7), and the first end of the fourth detection section are located.

[0011] Furthermore, an ink dam is established around the working electrolytic cell (8) and the calibration electrolytic cell (9). The dam includes a multi-layered structure that gradually expands, with a height of 75-100 μm. The ink-covered area also includes the middle of the first detection section, the middle of the second detection section, the upper end of the third detection section, and the upper end of the fourth detection section.

[0012] Furthermore, the detection parts of the first electrode (1), the second electrode (2), the third electrode (3), and the fourth electrode (4) are respectively connected to the first pin, the second pin, the third pin, and the fourth pin; electrode through holes (5) are respectively provided on the first pin, the second pin, the third pin, and the fourth pin, specifically conductive through holes.

[0013] The first electrode (1) is an auxiliary electrode, the second electrode (2) is a test electrode, the third electrode (3) is a calibration electrode, and the fourth electrode (4) is a reference electrode.

[0014] The bottom of the first electrode (1), the second electrode (2), the third electrode (3) and the fourth electrode (4) are modified with a copper layer with a thickness of at least 35.00 μm. The surface of the copper layer is modified with a metal layer including a nickel plating layer and a gold plating layer, with the nickel plating layer having a thickness of at least 3.00 μm and the gold plating layer having a thickness of at least 0.05 μm.

[0015] Furthermore, the surface of the detection part of the first electrode (1) is also modified with a platinum layer, the thickness of which is at least 0.50 μm; the surface of the detection part of the second electrode (2) is also modified with a nickel layer and a gold layer, the thickness of which is at least 3.00 μm and the thickness of which is at least 1.00 μm; the surface of the detection part of the third electrode (3) is also modified with a platinum layer, the thickness of which is at least 0.50 μm; and the surface of the detection part of the fourth electrode (4) is also modified with a silver chloride layer.

[0016] Furthermore, the spacing between the second and third interdigital strips is 100–200 μm; the widths of the second and third interdigital strips are the same, both being 100–200 μm.

[0017] Another objective of this invention is to provide an application of a four-electrode coplanar standard electrode with self-calibration function in the biochemical molecular detection of body fluids.

[0018] The four-electrode coplanar standard electrode with self-calibration function provided by the present invention is a four-electrode coplanar modified on the same plane of the electrode substrate, including a working electrode, a reference electrode and two auxiliary electrodes. The working electrode serves as a test electrode, with a detection layer (6) at the upper end and an interdigitated strip at the middle end. The auxiliary electrode serves as a calibration electrode, with an interdigitated strip parallel and equidistant to the aforementioned at the upper end, thereby constructing an interdigitated electrode structure between the working electrode and the calibration electrode to form a calibration area (7). The upper end of the reference electrode extends vertically to form a first end, which together with the calibration area (7) constitutes a calibration electrolytic cell (9). The upper end of the reference electrode extends upward to form a second end, which together with the detection layer (6) and the upper end of the first electrode constitutes a working electrolytic cell (8).

[0019] The calibration electrolytic cell (9) area of ​​the standard electrode can be used for electrode self-calibration. Specifically, the calibration is performed using the supercapacitor principle. The electrode can be self-calibrated in the calibration electrolytic cell without affecting the detection layer, thus determining the accuracy and sensitivity of the electrode. Subsequently, the liquid to be tested can be directly added to the detection layer area of ​​the working electrolytic cell, enabling the self-calibration and electrochemical detection steps to be completed in a short time.

[0020] During electrode use, the performance of the working electrode changes due to frequent voltage applications, or the electrode surface becomes contaminated, resulting in sensitivity loss. To address this issue, a calibration electrode is introduced to construct a calibration electrolytic cell (9) for the standard electrode. (Throughout the sensor's lifespan, the calibration electrode is not subjected to voltage and remains in a normal environment, thus its performance remains largely unchanged, representing the initial state of the working electrode.) The difference between the working electrode and the calibration electrode on EIS at any given moment is used to obtain the sensitivity change of the working electrode at that moment. This relationship can then be quantified to correct the sensor's calibration curve and obtain a calibration model. During sensor use, the current state of the working electrode can be obtained by performing EIS measurements, allowing for the manual correction of the sensor's calibration curve and achieving the electrode calibration function.

[0021] The specific calibration method is as follows: the test solution is added dropwise to the calibration electrolytic cell (9), and the EIS standard curve is measured. Then the test solution is added dropwise to the working electrolytic cell (8), and the EIS test curve is measured. Based on the sensor calibration model, the EIS test curve measured by the working electrolytic cell is corrected using the EIS standard curve to achieve the calibration function and ensure the accuracy of the working electrode test.

[0022] The lower end of the four electrodes is connected to electrode pins, and electrode pins are provided with electrode through holes (5), specifically conductive through holes, into which pins can be inserted, and the surface of the four electrodes can be modified or processed in a secondary manner by electrochemical methods.

[0023] The beneficial effects of this invention are:

[0024] (1) The present invention sets up a working electrode, a reference electrode and two auxiliary electrodes on the same plane, sets up a detection layer and interdigitated strips on the working electrode, and forms an interdigitated structure with one of the auxiliary electrodes, so that the electrode has a detection area and a calibration area, realizes the self-calibration function of the electrode, optimizes the function and structural design of the standard electrode, and expands the application field of the electrode.

[0025] (2) By setting electrode through holes on the electrode pins, the present invention can achieve secondary modification and secondary processing of the electrode through the electrode through holes by connecting the electroplating equipment to the electrode through holes, thereby realizing the purpose of secondary modification of the standard electrode according to the detection requirements and expanding the application range of the electrode; by designing the pin part to conform to the size of the USB interface, the entire electrode can be tightly connected to the USB interface, thereby realizing the connection with the conventional electrochemical workstation, which is convenient for use and replacement.

[0026] (3) The present invention integrates four electrodes onto a fixed-size electrode substrate, realizing the integration of three-electrode systems with different functions on the same plane, greatly reducing and fixing the electrode spacing, reducing detection interference, realizing the miniaturization of multi-electrode coplanar electrodes, and greatly improving electrode sensitivity and accuracy. Attached Figure Description

[0027] The invention will be further illustrated with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the invention. For those skilled in the art, other drawings can be obtained based on the following drawings without any creative effort.

[0028] Figure 1 This is a front view of a four-electrode coplanar standard electrode with self-calibration function;

[0029] Figure 2 This is a schematic diagram of the back side of a four-electrode coplanar standard electrode with self-calibration function;

[0030] Figure 3 This is a schematic diagram of the front side of an ink-covered standard electrode with a self-calibrating four-electrode coplanar structure.

[0031] Figure 4 This is a schematic diagram of the ink-covered back side of a four-electrode coplanar standard electrode with self-calibration function;

[0032] Figure 5 The figures (a) and (b) are the dissolution voltammetry curves (a) and the fitting curves (b) of current density versus copper ion concentration for the detection of different concentrations of copper ions in the human body by the four electrodes of the electrochemical sensing detection of this invention.

[0033] Figure 6 This is a repeatability test of the four electrodes for copper ion detection in the electrochemical sensing detection of this invention;

[0034] Figure 7 The open-circuit potential-time relationship diagram and the linear fitting curve (b) of pH value (a) and open-circuit potential for the detection of different pH values ​​of the human body by the four electrodes of the electrochemical sensing detection of this invention are shown.

[0035] Figure 8 This invention relates to a test of the anti-interference performance of the four-electrode electrochemical sensing detection system for human pH detection.

[0036] Legend:

[0037] 1. First electrode; 2. Second electrode; 3. Third electrode; 4. Fourth electrode; 5. Electrode through hole; 6. Detection layer; 7. Calibration area; 8. Working electrolytic cell; 9. Calibration electrolytic cell; 10. First layer ink; 11. Second layer ink; 12. Third layer ink. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail with reference to the following specific embodiments and the accompanying drawings.

[0039] Example 1

[0040] As attached Figure 1 As shown, this invention provides a four-electrode coplanar standard electrode with self-calibration function. Specifically, it includes an electrode substrate made of FR-4 material, measuring 35.0 x 12.0 mm and 0.8 mm thick. Four coplanar electrodes are fixedly disposed on the electrode substrate, from left to right: a first electrode 1, a second electrode 2, a third electrode 3, and a fourth electrode 4. Each electrode includes a lead portion and a detection portion. The lead portions are equidistantly disposed at one end of the standard electrode, namely the first lead, the second lead, the third lead, and the fourth lead. The detection portion is disposed at the other end of the standard electrode. The device is connected to four electrode pins and includes a first detection section, a second detection section, a third detection section, and a fourth detection section. A detection layer 6 is connected to the upper end of the second detection section. Several second interdigitated strips extend vertically from the middle of the second detection section, with the total area of ​​the second interdigitated strips being one-quarter of the area of ​​the detection layer 6. Several third interdigitated strips extend vertically from the upper end of the third detection section. The second and third interdigitated strips are arranged in a comb-like, equidistant, staggered pattern to form an interdigitated structure, creating a calibration area 7. The distance between the second and third interdigitated strips is 200 μm. The width of the second and third interdigitated strips is the same, both being 200 μm. The second detection section is located below the calibration area 7. The fourth detection section extends from its upper end with a first end and a second end.

[0041] The electrode surface is provided with a working electrolytic cell 8, including the area where the first detection section, the detection layer 6 and the second end of the fourth detection section are located; the electrode surface is provided with a calibration electrolytic cell 9, including the area where the second detection section, the third detection section, the calibration area 7 and the first end of the fourth detection section are located.

[0042] The working electrolytic cell 8 and the calibration electrolytic cell 9 are surrounded by ink dams, which consist of a multi-layered structure that gradually expands, as shown in the attached diagram. Figure 3 Appendix Figure 4 As shown, the first layer of ink covers the front and back sides of the unmodified metal electrode substrate, as well as the middle of the first detection section, the upper middle electrode strip of the second detection section connected to the detection layer 6 and the second interdigital strip, the upper end of the third detection section, and the upper end of the fourth detection section connected to two electrode strips at two ends; the second layer of ink covers the area between the upper side of the second end of the fourth detection section and the lower side of the detection layer 6; the third layer of ink covers the area between the outer side of the first detection section and the outer side of the first end of the fourth detection section and the edge of the electrode substrate, with each layer of ink having a thickness of 25 μm.

[0043] As attached Figure 2As shown, the detection parts of the first electrode 1, the second electrode 2, the third electrode 3, and the fourth electrode 4 are respectively connected to the first pin, the second pin, the third pin, and the fourth pin; the first pin, the second pin, the third pin, and the fourth pin are respectively provided with electrode through holes 5, specifically conductive through holes, with a diameter of 1.0 mm.

[0044] The first electrode 1 is an auxiliary electrode, the second electrode 2 is a test electrode, the third electrode 3 is a calibration electrode, and the fourth electrode 4 is a reference electrode.

[0045] The bottom of the first electrode 1, the second electrode 2, the third electrode 3 and the fourth electrode 4 are modified with a copper layer with a thickness of 35.00 μm. The surface of the copper layer is modified with a metal layer including a nickel plating layer and a gold plating layer. The nickel plating layer has a thickness of 3.00 μm and the gold plating layer has a thickness of 0.05 μm.

[0046] The surface of the detection part of the first electrode 1 is also modified with a platinum layer with a thickness of 0.50 μm; the surface of the detection part of the second electrode 2 is also modified with a nickel layer and a gold layer with a thickness of 3.00 μm and a gold layer with a thickness of 1.00 μm; the surface of the detection part of the third electrode 3 is also modified with a platinum layer with a thickness of 0.50 μm; and the surface of the detection part of the fourth electrode 4 is also modified with a silver-silver chloride layer with a thickness of 5.00 μm.

[0047] Example 2

[0048] A four-electrode coplanar standard electrode with self-calibration function specifically includes: an electrode substrate made of FR-4 material, measuring 35.0 x 12.0 mm and 0.8 mm thick; four coplanar electrodes are fixedly disposed on the electrode substrate, namely, a first electrode 1, a second electrode 2, a third electrode 3, and a fourth electrode 4, from left to right. Each electrode includes a lead portion and a detection portion. The lead portions of the four electrodes are equidistantly disposed at one end of the standard electrode, namely, a first lead, a second lead, a third lead, and a fourth lead; the detection portion of the four electrodes is disposed at the other end of the standard electrode. The pins are connected to each other, including a first detection section, a second detection section, a third detection section, and a fourth detection section. A detection layer 6 is connected to the upper end of the second detection section. Several second interdigitated strips extend vertically from the middle of the second detection section, with the total area of ​​the second interdigitated strips being one-quarter of the area of ​​the detection layer 6. Several third interdigitated strips extend vertically from the upper end of the third detection section. The second and third interdigitated strips are arranged in a comb-like, equidistant, staggered pattern to form an interdigitated structure, creating a calibration area 7. The distance between the second and third interdigitated strips is 100 μm. The width of the second and third interdigitated strips is the same, both being 100 μm. The second detection section is located below the calibration area 7. The fourth detection section extends from its upper end with a first end and a second end.

[0049] The electrode surface is provided with a working electrolytic cell 8, including the area where the first detection section, the detection layer 6 and the second end of the fourth detection section are located; the electrode surface is provided with a calibration electrolytic cell 9, including the area where the second detection section, the third detection section, the calibration area 7 and the first end of the fourth detection section are located.

[0050] An ink dam is established around the working electrolytic cell 8 and the calibration electrolytic cell 9. The dam includes a multi-layered structure that gradually expands. The first layer of ink covers the front and back of the unmodified metal of the electrode substrate, as well as the middle of the first detection section, the upper middle electrode strip of the second detection section connected to the detection layer 6 and the second interdigital strip, the upper end of the third detection section, and the upper end of the fourth detection section connected to electrode strips with two ends. The second layer of ink covers the area between the upper side of the second end of the fourth detection section and the lower side of the detection layer 6. The third layer of ink covers the area between the outer side of the first detection section and the outer side of the first end of the fourth detection section and the edge of the electrode substrate. The thickness of each ink layer is 30 μm.

[0051] The detection parts of the first electrode 1, the second electrode 2, the third electrode 3, and the fourth electrode 4 are respectively connected to the first pin, the second pin, the third pin, and the fourth pin; each of the first pin, the second pin, the third pin, and the fourth pin is provided with an electrode through hole 5, specifically a conductive through hole, with a diameter of 1.0 mm.

[0052] The first electrode 1 is an auxiliary electrode, the second electrode 2 is a test electrode, the third electrode 3 is a calibration electrode, and the fourth electrode 4 is a reference electrode.

[0053] The bottom of the first electrode 1, the second electrode 2, the third electrode 3 and the fourth electrode 4 are modified with a copper layer with a thickness of 40.00 μm. The surface of the copper layer is modified with a metal layer including a nickel plating layer and a gold plating layer. The nickel plating layer has a thickness of 5.00 μm and the gold plating layer has a thickness of 0.10 μm.

[0054] The surface of the detection section of the first electrode 1 is also modified with a platinum layer with a thickness of 0.10 μm; the surface of the detection section of the second electrode 2 is also modified with a nickel layer and a gold layer with a thickness of 5.00 μm and a gold layer with a thickness of 3.00 μm; the surface of the detection section of the third electrode 3 is also modified with a platinum layer with a thickness of 1.00 μm; and the surface of the detection section of the fourth electrode 4 is also modified with a silver-silver chloride layer with a thickness of 5.00 μm.

[0055] Example 3

[0056] A self-calibrating four-electrode coplanar standard electrode specifically includes: a ceramic substrate electrode base with dimensions of 35.0 x 12.0 mm and a thickness of 0.8 mm; four coplanar electrodes are fixedly disposed on the electrode base, namely, a first electrode 1, a second electrode 2, a third electrode 3, and a fourth electrode 4, from left to right. Each electrode includes a lead portion and a detection portion. The lead portions of the four electrodes are equidistantly disposed at one end of the standard electrode, namely, a first lead, a second lead, a third lead, and a fourth lead; the detection portion of the four electrodes is disposed at the other end of the standard electrode and is connected to the lead portions of the four electrodes. The device comprises four interconnected detection units: a first detection unit, a second detection unit, a third detection unit, and a fourth detection unit. The upper end of the second detection unit is connected to a detection layer 6. Several second interdigitated strips extend vertically from the middle of the second detection unit, with the total area of ​​the second interdigitated strips being one-quarter of the area of ​​the detection layer 6. Several third interdigitated strips extend vertically from the upper end of the third detection unit. The second and third interdigitated strips are arranged in a comb-like, equidistant, staggered pattern to form an interdigitated structure, creating a calibration area 7. The distance between the second and third interdigitated strips is 150 μm. The width of the second and third interdigitated strips is the same, also 150 μm. The second detection unit is located below the calibration area 7. The upper end of the fourth detection unit extends into a first end and a second end.

[0057] The electrode surface is provided with a working electrolytic cell 8, including the area where the first detection section, the detection layer 6 and the second end of the fourth detection section are located; the electrode surface is provided with a calibration electrolytic cell 9, including the area where the second detection section, the third detection section, the calibration area 7 and the first end of the fourth detection section are located.

[0058] An ink dam is established around the working electrolytic cell 8 and the calibration electrolytic cell 9. The dam includes a multi-layered structure that gradually expands. The first layer of ink covers the front and back of the unmodified metal of the electrode substrate, as well as the middle of the first detection section, the upper middle electrode strip of the second detection section connected to the detection layer 6 and the second interdigital strip, the upper end of the third detection section, and the upper end of the fourth detection section connected to electrode strips with two ends. The second layer of ink covers the area between the upper side of the second end of the fourth detection section and the lower side of the detection layer 6. The third layer of ink covers the area between the outer side of the first detection section and the outer side of the first end of the fourth detection section and the edge of the electrode substrate. The thickness of each ink layer is 30 μm.

[0059] The detection parts of the first electrode 1, the second electrode 2, the third electrode 3, and the fourth electrode 4 are respectively connected to the first pin, the second pin, the third pin, and the fourth pin; each of the first pin, the second pin, the third pin, and the fourth pin is provided with an electrode through hole 5, specifically a conductive through hole, with a diameter of 1.0 mm.

[0060] The first electrode 1 is an auxiliary electrode, the second electrode 2 is a test electrode, the third electrode 3 is a calibration electrode, and the fourth electrode 4 is a reference electrode.

[0061] The bottom of the first electrode 1, the second electrode 2, the third electrode 3 and the fourth electrode 4 are modified with a copper layer with a thickness of 45.00 μm. The surface of the copper layer is modified with a metal layer including a nickel plating layer and a gold plating layer. The nickel plating layer has a thickness of 5.50 μm and the gold plating layer has a thickness of 0.30 μm.

[0062] The surface of the detection part of the first electrode 1 is also modified with a platinum layer with a thickness of 0.30 μm; the surface of the detection part of the second electrode 2 is also modified with a nickel layer and a gold layer with a thickness of 5.50 μm and a gold layer with a thickness of 5.00 μm; the surface of the detection part of the third electrode 3 is also modified with a platinum layer with a thickness of 2.00 μm; and the surface of the detection part of the fourth electrode 4 is also modified with a silver-silver chloride layer with a thickness of 5.00 μm.

[0063] Example 4

[0064] Applications of the self-calibration function of a four-electrode coplanar standard electrode:

[0065] Figure 5 and Figure 6 To test the response performance of the four-electrode electrochemical sensing detection system prepared in Example 1 to copper ions in the human body. A three-electrode detection system was constructed using the first electrode (1), the second electrode (2), and the fourth electrode (4), with the third electrode (3) serving as the calibration electrode.

[0066] The specific calibration method is as follows: A copper ion detection solution is added to the calibration electrolytic cell (9), and the EIS standard curve is measured. Then, copper ion detection is added to the working electrolytic cell (8), and the EIS test curve is measured. Based on the sensor calibration model, the EIS test curve of the working electrolytic cell is corrected using the EIS standard curve to calibrate the sensing electrode and ensure the accuracy of the test. Subsequently, a three-electrode system is used to test the response performance of copper ions at different concentrations in body fluids.

[0067] As attached Figure 5 The figure shows the dissolution voltammetry curves and the fitting curves of current density versus copper ion concentration for the detection of different concentrations of copper ions in the human body using the electrochemical sensing four-electrode method prepared in this invention. From... Figure 5 As can be seen from a, as the copper ion concentration increases from 100 to 400 ppb, its response current density gradually increases. Figure 5 As can be seen from b, the response current density and concentration fitting curve show a good linear relationship, indicating that the sensing electrode prepared in this invention has a good response performance to copper ions in the human body.

[0068] To assess the reliability of the three-electrode system, a copper ion standard solution of the same concentration (200 ppb) was tested eight times consecutively under the same detection conditions. The test results are as follows: Figure 6As shown in the figure, the dissolution curves of the eight tests highly overlap, the peak current density fluctuates within a very small range, and the relative standard deviation (RSD) of the measurement results is 2.26%, which indicates that the sensing electrode of the present invention has high reliability.

[0069] Example 5

[0070] Applications of self-calibrating four-electrode coplanar standard electrodes in biochemical molecular detection:

[0071] Figure 7 and Figure 8 This study investigates the performance of a four-electrode electrochemical sensor designed in Implementation Case 2 for detecting human body pH. A two-electrode detection system was established using the first electrode (1) and the second electrode (2), with the third electrode (3) serving as the calibration electrode. When electrode calibration was required, a pH buffer solution was added to the calibration electrolytic cell (9), and the EIS standard curve was measured. Then, the pH buffer solution was added to the working electrolytic cell (8), and the EIS test curve was measured. Based on the sensor calibration model, the EIS test curve of the working electrolytic cell was corrected using the EIS standard curve, thus completing the calibration of the sensing electrodes. Subsequently, the two-electrode system was used to test human body pH.

[0072] Figure 7 The potential-time curves (a) and potential-pH linear fitting curves (b) are shown for buffer solutions with pH values ​​of 4.0, 5.0, 6.0, 7.0, 8.0, and 9.0. The figures show that the pH-tested potential is stable, and its fitting curve with pH is good, with R... 2 =0.997, indicating that the electrode of the present invention has excellent response performance to human body pH value.

[0073] Figure 8 This invention relates to a test of the anti-interference performance of the four-electrode electrochemical sensing detection system for human pH detection. The main interfering ions in human sweat include Na+. + K + Mg 2+ Li + and Ca 2+ As can be seen from the figure, when several interfering ions were added, the open-circuit potential curve did not show obvious fluctuations, indicating that the electrode of the present invention has good anti-interference performance against common ions in the human body.

[0074] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0075] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. Technical details not described in detail in this invention can all be implemented using any existing technology in the art. In particular, all technical features not described in detail in this invention can be implemented using any existing technology.

Claims

1. A four-electrode coplanar standard electrode with self-calibration function, comprising an electrode substrate, characterized in that, Four electrodes, coplanar with each other, are fixedly disposed on the electrode substrate. From left to right, they are the first electrode (1), the second electrode (2), the third electrode (3), and the fourth electrode (4). Each of the four electrodes includes a lead portion and a detection portion. The lead portions of the four electrodes are equidistantly arranged, and from left to right, they are the first lead, the second lead, the third lead, and the fourth lead. The detection portions of the four electrodes are connected to the lead portions of the four electrodes respectively, including the first detection portion, the second detection portion, the third detection portion, and the fourth detection portion. The upper end of the second detection portion is connected to a detection layer (6). Several second interdigitated strips extend vertically from the middle of the second detection portion. Several third interdigitated strips extend vertically from the upper end of the third detection portion. The second interdigitated strips and the third interdigitated strips are arranged in a comb-like, equidistant, staggered manner to form an interdigitated structure, forming a calibration area (7). The upper end of the fourth detection portion extends from bottom to top, with the first end and the second end extending from bottom to top. The electrode substrate surface is provided with a working electrolytic cell (8), which includes the area where the first detection part, the detection layer (6), and the second end of the fourth detection part are located; the electrode substrate surface is provided with a calibration electrolytic cell (9), which includes the area where the second detection part, the third detection part, the calibration area (7), and the first end of the fourth detection part are located; The first electrode (1) is an auxiliary electrode, the second electrode (2) is a test electrode, the third electrode (3) is a calibration electrode, and the fourth electrode (4) is a reference electrode; The four electrodes are provided with electrode through holes (5), specifically conductive through holes, for inserting pins, and the surface of the four electrodes is modified secondary by an electrochemical method.

2. The four-electrode coplanar standard electrode with self-calibration function according to claim 1, characterized in that, The total area of ​​the second interdigitated strip is one-quarter of the area of ​​the detection layer (6).

3. A four-electrode coplanar standard electrode with self-calibration function according to claim 1, characterized in that, The first detection unit, the second detection unit, the third detection unit and the fourth detection unit are respectively connected to the first pin, the second pin, the third pin and the fourth pin; the first pin, the second pin, the third pin and the fourth pin are respectively provided with electrode through holes (5), specifically conductive through holes.

4. A four-electrode coplanar standard electrode with self-calibration function according to claim 1, characterized in that, The bottom of the first electrode (1), the second electrode (2), the third electrode (3) and the fourth electrode (4) are decorated with a copper layer, the copper layer having a thickness of at least 35.00 μm, and the surface of the copper layer is decorated with a metal layer, the metal layer including a nickel layer and a gold layer, the nickel layer having a thickness of at least 3.00 μm and the gold layer having a thickness of at least 0.05 μm.

5. A four-electrode coplanar standard electrode with self-calibration function according to claim 1, characterized in that, The surface of the first detection unit is further modified with a platinum layer, the platinum layer having a thickness of at least 0.50 μm; the surface of the second detection unit is further modified with a nickel layer and a gold layer, the nickel layer having a thickness of at least 3.00 μm and the gold layer having a thickness of at least 1.00 μm; the surface of the third detection unit is further modified with a platinum layer, the platinum layer having a thickness of at least 0.50 μm; and the surface of the fourth detection unit is further modified with a silver chloride layer.

6. A four-electrode coplanar standard electrode with self-calibration function according to claim 1, characterized in that, The distance between the second and third interdigitated fingers is 100-200 μm; the width of the second and third interdigitated fingers is the same, both being 100-200 μm.

7. The application of a four-electrode coplanar standard electrode with self-calibration function as described in any one of claims 1 to 6 in the biochemical molecular detection of body fluids.

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