Electrochemical water quality microsensor

Abstract

An electrochemical water quality microsensor is provided, which can be applied to the field of water quality detection sensor technology. The sensor includes: a substrate, a thin-layer detection cavity structure, a common counter electrode, a common reference electrode, a detection working electrode, and a pH control electrode, wherein the thin-layer detection cavity structure includes a groove, an inlet, and an outlet; a cavity is formed between the groove of the thin-layer detection cavity structure and the substrate; the sample to be detected flows into the cavity from the inlet and out from the outlet; the pH control electrode and the detection working electrode form a circular concentric array, distributed in a double helix structure. By adjusting the potential or current applied to the pH control electrode, the pH value of the solution in the vicinity of the working electrode is controlled, thereby avoiding the acidification or alkalization steps required in conventional electrochemical detection and analysis, achieving reagent-free or low-reagent detection, and greatly simplifying the process of using electrochemical methods to detect pollutants in water.

Description

Technical Field

[0001] The present disclosure relates to the technical field of water quality detection sensors, and in particular to an electrochemical water quality microsensor. Background Art

[0002] Traditional water quality testing technologies primarily include atomic absorption spectrophotometry, atomic fluorescence spectrometry, and inductively coupled plasma mass spectrometry. While these technologies offer good detection performance, they are often characterized by bulky instrumentation, complex operation, long testing cycles, high analytical costs, and the need for pre-concentration and separation techniques (such as solid-phase microextraction and dispersive liquid-liquid microextraction). Consequently, they are often limited to laboratory deployment, making them difficult to use for rapid on-site testing and responding to sudden water pollution incidents. The environmental monitoring sector urgently needs simple, rapid, sensitive, and miniaturized water pollution detection technologies suitable for on-site testing. Water pollution detection technologies with these characteristics are currently a key development direction for water quality testing.

[0003] Electrochemical sensors are devices or apparatuses that sense (or respond to) biological or chemical quantities and convert them into electrical signals according to specific patterns. They can directly convert chemical signals into electrical signals and offer advantages such as high sensitivity, low detection limits, simple operation, low equipment cost, and ease of miniaturization. They possess unique advantages for rapid on-site water quality testing and are considered the most suitable method for such testing. Currently, research on the use of electrochemical sensors for the detection of water quality parameters such as pH, dissolved oxygen, nitrate, ammonia nitrogen, chemical oxygen demand, and heavy metals has been widely reported. These research results have found widespread practical application in wastewater treatment, aquaculture, lake and reservoir monitoring, organic agriculture, and environmental monitoring.

[0004] Under current technological conditions, the use of electrochemical sensors to detect pollutants in water still relies on the use of numerous chemical reagents. For example, before using stripping voltammetry to detect heavy metal ions, both the test water sample and the standard sample solution must be acidified. The degree of acidification required varies depending on the type of heavy metal ion and the detection electrode used. When detecting lead using a carbon electrode, the test solution must be adjusted to a weakly acidic pH of approximately 4.5. When detecting mercury using a gold electrode, the test solution must be acidified to a strongly acidic pH of 1 using highly concentrated hydrochloric acid. Electrochemical detection of nitrate in water using copper or silver modified electrodes generally requires adjusting the test sample to an acidic pH of 1-2. Electrochemical detection of ammonia nitrogen in water using a platinum electrode generally requires adjusting the test sample to a strongly alkaline pH of >12. This complex and hazardous reagent preparation requirement not only increases the number of steps and testing costs, but also creates additional chemical hazard handling and management challenges, naturally increasing the potential for errors and mishandling. Summary of the Invention

[0005] (1) Technical issues to be resolved

[0006] In order to solve the problems existing in the electrochemical detection of pollutants in water in the prior art, the embodiments of the present disclosure provide an electrochemical water quality microsensor, which is designed by designing two functionalized microelectrodes adjacent to each other and distributed in a double helix structure and a microflow sensor with a thin layer detection cell, wherein one of the two functionalized microelectrodes is used as a working electrode for electrochemical detection, and the other is used as an electrode for pH control of the solution in the detection cell. By adjusting the potential or current applied to the pH control electrode, the pH value of the solution in the vicinity of the working electrode is controlled, thereby avoiding the acidification or alkalization operation steps required for conventional electrochemical detection and analysis, realizing reagent-free / low-reagent detection, and greatly simplifying the process of using electrochemical methods to detect pollutants in water. This invention is of great significance to water quality detection, and at the same time has important application value for on-site in-situ analysis and continuous monitoring of pollutants in water by electrochemical sensors.

[0007] (2) Technical solution

[0008] In view of the above problems, an embodiment of the present disclosure provides an electrochemical water quality microsensor.

[0009] According to the first aspect of the present disclosure, an electrochemical water quality microsensor is provided, which is characterized by comprising: a substrate, a thin-layer detection cavity structure, a common counter electrode, a common reference electrode, a detection working electrode and a pH control electrode, wherein the thin-layer detection cavity structure includes a groove, an injection port and a sample outlet; a cavity is formed between the groove of the thin-layer detection cavity structure and the substrate; the sample to be detected flows into the cavity from the injection port and flows out from the sample outlet; one end of the common counter electrode, the common reference electrode, the detection working electrode and the pH control electrode is located inside the cavity.

[0010] In some exemplary embodiments, the pH controlling electrode and the detection working electrode form a circular concentric array and are distributed in a double helix structure; the pH controlling electrode is used to control the pH value of the solution, and the pH value of the solution is related to the potential or current applied to the pH controlling electrode; and the distance between the detection working electrode and the pH controlling electrode does not exceed the range in which the pH controlling electrode can control the pH value of the solution.

[0011] In some exemplary embodiments, the geometric size of the detection working electrode is on the order of micrometers; the geometric size of the pH control electrode is on the order of micrometers; and the geometric size of the common counter electrode is on the order of millimeters.

[0012] In some exemplary embodiments, at least one of the following features is included: the height of the cavity is 50μm-400µm; the electrode width of the detection working electrode is 2μm-20µm; the electrode width of the pH control electrode is 2μm-20µm; and the spacing between the pH control electrode and the detection working electrode is 1 to 5 times the width of the pH control electrode.

[0013] In some exemplary embodiments, the structure of the common counter electrode is a ring structure; the electrode width of the common counter electrode is 1mm-5mm; the distance between the inner ring of the common counter electrode and the double helix structure formed by the detection working electrode and the pH control electrode is 5mm-25mm; the area of ​​the common counter electrode is greater than 1000 times the area of ​​the detection working electrode.

[0014] In some exemplary embodiments, the common reference electrode includes an on-chip integrated Ag / AgCl solid-state reference electrode, wherein the preparation method of Ag / AgCl includes: preparing it by chlorinating a metal silver film in an acidic solution environment; or preparing it by coating Ag / AgCl slurry on a gold base electrode.

[0015] In some exemplary embodiments, the detection working electrode, the common counter electrode and the common reference electrode form a micro-electrochemical three-electrode system, which can perform electrochemical scanning to achieve the identification and detection of pollutants in water bodies; and the pH control electrode, the common counter electrode and the common reference electrode form an electrochemical pH control system, which performs electrochemical constant current and / or constant voltage scanning to maintain the hydrolysis reaction in a specific area of ​​the thin-layer detection cavity, so as to achieve the control of the pH value of the solution in the detection area of ​​the detection working electrode.

[0016] In some exemplary embodiments, the material of the substrate includes one of silicon or glass. When the material of the substrate is silicon, an insulating film is grown on the silicon surface, and the material of the insulating film includes silicon oxide and silicon nitride; the material of the pH control electrode includes gold; the material of the common counter electrode includes gold; the material of the detection working electrode is related to the type of pollutant to be detected, and the material of the detection working electrode includes one of gold, platinum, silver, copper or carbon.

[0017] In some exemplary embodiments, the surfaces of the pH control electrode, the common counter electrode, the detection working electrode and the common reference electrode are covered with an insulating layer, and the material of the insulating layer includes one of silicon oxide, silicon nitride, a composite film composed of silicon oxide and silicon nitride, or a photoresist.

[0018] In some exemplary embodiments, at least one of the following features is included: a thin-layer detection cavity structure is prepared by using a PDMS material using a demolding process; the thin-layer detection cavity structure and the substrate are encapsulated and formed by an oxygen plasma bonding process; and the preparation method of the detection working electrode, the pH control electrode, the common counter electrode and the common reference electrode includes one of a magnetron sputtering method or an electron beam evaporation method.

[0019] (3) Beneficial effects

[0020] It can be seen from the above technical solutions that the electrochemical water quality microsensor provided by the embodiments of the present disclosure has at least one of the following beneficial effects:

[0021] (1) Two adjacent functionalized microelectrodes with a double-helix structure are designed, and a microfluidic sensor with a thin-layer detection cell is designed. Among the two functionalized microelectrodes, one electrode is used as a working electrode for electrochemical detection, and the other is used as a pH control electrode for the solution in the detection cell. By adjusting the potential or current applied to the pH control electrode, the pH value of the solution in the area near the working electrode is controlled, thereby avoiding the acidification or alkalization steps required for conventional electrochemical detection and analysis, achieving reagent-free / low-reagent detection, and greatly simplifying the process of using electrochemical methods to detect pollutants in water.

[0022] (2) This invention is of great significance to water quality testing, and also has important application value in the on-site in-situ analysis and continuous monitoring of pollutants in water by electrochemical sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0024] Figure 1 The overall structure of an electrochemical water quality microsensor according to an embodiment of the present disclosure is schematically shown;

[0025] Figure 2 Schematically shows a schematic diagram of the explosion structure of an electrochemical water quality microsensor according to an embodiment of the present disclosure; and

[0026] Figure 3 The figure schematically shows a planar distribution diagram of an electrochemical water quality microsensor according to an embodiment of the present disclosure.

[0027] Reference numerals:

[0028] 1-thin layer detection cavity structure; 11-inlet; 12-outlet; 13-groove; 2-substrate; 3-cavity; 4-common counter electrode; 5-pH control electrode; 6-detection working electrode; 7-common reference electrode. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the present disclosure more clearly understood, the present disclosure is further described below in conjunction with specific embodiments and with reference to the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present disclosure, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present disclosure without inventive effort are intended to fall within the scope of protection of the present disclosure.

[0030] Figure 1 The overall structure of an electrochemical water quality microsensor according to an embodiment of the present disclosure is schematically shown; Figure 2 Schematically shows a schematic diagram of the explosion structure of an electrochemical water quality microsensor according to an embodiment of the present disclosure; and Figure 3 The figure schematically shows a planar distribution diagram of an electrochemical water quality microsensor according to an embodiment of the present disclosure.

[0031] like Figure 1 、 Figure 2 and Figure 3As shown, an electrochemical water quality microsensor according to an embodiment of the present disclosure includes: a substrate 2, a thin-layer detection cavity structure 1, a common counter electrode 4, a common reference electrode 7, a detection working electrode 6 and a pH control electrode 5, wherein the thin-layer detection cavity structure 1 includes a groove 13, an injection port 11 and a sample outlet 12; a cavity 3 is formed between the groove 13 of the thin-layer detection cavity structure 1 and the substrate 2; the sample to be detected flows into the cavity 3 from the injection port 11 and flows out from the sample outlet 12; one end of the common counter electrode 4, the common reference electrode 7, the detection working electrode 6 and the pH control electrode 5 are located inside the cavity 3.

[0032] The microsensor is fabricated using micromachining (MEMS) technology and integrates four functional electrodes in a thin layer detection cavity. The detection working electrode 6 and the pH control electrode 5 are adjacent to each other and are distributed in a double helical structure. Figure 3 ; The detection working electrode 6, the common counter electrode 4 and the common reference electrode 7 form a micro-electrochemical three-electrode system, which can perform electrochemical scanning to detect pollutants in water bodies; and the pH control electrode 5, the common counter electrode 4 and the common reference electrode 7 form an electrochemical pH control system, which performs electrochemical constant current and / or constant voltage scanning to maintain the hydrolysis reaction in the thin layer detection cavity, so as to realize the regulation of the pH value of the solution in the detection area of ​​the detection working electrode 6.

[0033] In some exemplary embodiments, the pH controlling electrode 5 and the detection working electrode 6 form a circular concentric array and are distributed in a double helix structure; the pH controlling electrode 5 is used to control the pH value of the solution, and the pH value of the solution is related to the potential or current applied to the pH controlling electrode 5; and the distance between the detection working electrode 6 and the pH controlling electrode 5 does not exceed the range in which the pH controlling electrode 5 can control the pH value of the solution.

[0034] By adjusting the potential or current applied to the pH control electrode 5, the pH value of the solution in the area near the working electrode is controlled, thereby avoiding the acidification or alkalization operation steps required in conventional electrochemical detection and analysis, realizing reagent-free / low-reagent detection, and greatly simplifying the process of using electrochemical methods to detect pollutants in water.

[0035] In some exemplary embodiments, the geometric dimensions of the detection working electrode 6 are in the micrometer range; the geometric dimensions of the pH control electrode 5 are in the micrometer range; and the spacing between the pH control electrode 5 and the detection working electrode 6 is 1-5 times the width of the pH control electrode 5.

[0036] For example, the electrode width of the detection working electrode 6 is 2 μm-20 μm; the electrode width of the pH control electrode 5 is 2 μm-20 μm.

[0037] In some exemplary embodiments, the common counter electrode 4 is annular; its dimensions are in the micrometer range; the distance between the inner ring of the common counter electrode 4 and the double helix structure formed by the detection working electrode 6 and the pH control electrode 5 is 5 mm to 25 mm; and the area of ​​the common counter electrode 4 is 1000 times greater than that of the detection working electrode 6. Optionally, the electrode width of the common counter electrode 4 is 1 mm to 5 mm.

[0038] In some exemplary embodiments, the material of substrate 2 includes silicon, glass, etc. When substrate 2 is a silicon wafer, an insulating film needs to be grown on the surface of the silicon wafer. Optionally, the insulating film includes silicon oxide and silicon nitride.

[0039] In some exemplary embodiments, the material of the pH control electrode 5 includes gold; the material of the common counter electrode 4 includes gold; and the material of the detection working electrode 6 is related to the type of pollutant to be detected, and the material of the detection working electrode 6 includes one of gold, platinum, silver, copper, or carbon. Optionally, the detection working electrode 6, the pH control electrode 5, the common reference electrode 7, and the common counter electrode 4 are prepared by magnetron sputtering or electron beam evaporation.

[0040] In some exemplary embodiments, the common reference electrode 7 includes an on-chip integrated Ag / AgCl solid-state reference electrode, wherein the preparation method of Ag / AgCl includes: preparing it by chlorinating a metal silver film in an acidic solution environment; or preparing it by coating Ag / AgCl slurry on a gold substrate 2 electrode.

[0041] Optionally, the surface of the electrode layer is covered with an insulating layer, which may be silicon oxide, silicon nitride, a composite film of silicon oxide and silicon nitride, or SU8 photoresist, to define the surface of each sensitive electrode and the corresponding pad position.

[0042] In some exemplary embodiments, the thin-layer detection cavity structure 1 is made of PDMS material (polydimethylsiloxane, an organic silicon polymer material composed of alternating silicon and oxygen atoms and carrying methyl groups. These methyl groups give PDMS good plasticity and elasticity, and its physical and chemical properties can be changed by adjusting the molecular weight and cross-linking degree) using a demolding process. The thin-layer detection cavity structure 1 and the substrate 2 are encapsulated and molded by an oxygen plasma bonding process. Optionally, the height of the cavity 3 is 50μm-400µm.

[0043] In some exemplary embodiments, the surfaces of the pH control electrode 5, the common counter electrode 4, the detection working electrode 6 and the common reference electrode 7 are covered with an insulating layer, and the material of the insulating layer includes one of silicon oxide, silicon nitride, a composite film composed of silicon oxide and silicon nitride, or a photoresist.

[0044] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. An electrochemical water quality microsensor, characterized in that: include: Substrate, thin layer detection cavity structure, common counter electrode, common reference electrode, detection working electrode and pH control electrode, The thin layer detection cavity structure includes a groove, an inlet and an outlet; A cavity is formed between the groove of the thin-layer detection cavity structure and the substrate; The sample to be tested flows into the cavity from the sample inlet and flows out from the sample outlet; The common counter electrode, the common reference electrode, the detection working electrode and one end of the pH control electrode are located inside the cavity.

2. The electrochemical water quality microsensor according to claim 1, characterized in that: The pH regulating electrode and the detection working electrode form a circular concentric array and are distributed in a double helix structure; The pH control electrode is used to control the pH value of the solution, and the pH value of the solution is related to the potential or current applied to the pH control electrode; as well as The distance between the detection working electrode and the pH control electrode does not exceed the range in which the pH control electrode can control the pH value of the solution.

3. The electrochemical water quality microsensor according to claim 2, characterized in that: The geometric size of the detection working electrode is in the micrometer range; The geometric size of the pH control electrode is in the micrometer range; and The geometric dimensions of the common counter electrode are in the order of millimeters.

4. The electrochemical water quality microsensor according to claim 3, characterized in that: Include at least one of the following features: The height of the cavity is 50 μm-400 μm; The electrode width of the detection working electrode is 2μm-20μm; The electrode width of the pH control electrode is 2μm-20μm; The distance between the pH regulating electrode and the detection working electrode is 1 to 5 times the width of the pH regulating electrode.

5. The electrochemical water quality microsensor according to claim 3, characterized in that: The structure of the common counter electrode is a ring structure; The electrode width of the common counter electrode is 1 mm to 5 mm; The distance between the inner ring of the common counter electrode and the double helix structure formed by the detection working electrode and the pH control electrode is 5 mm to 25 mm; The area of ​​the common counter electrode is 1000 times greater than the area of ​​the detection working electrode.

6. The electrochemical water quality microsensor according to claim 2, characterized in that: The common reference electrode includes an on-chip integrated Ag / AgCl solid-state reference electrode, wherein the preparation method of the Ag / AgCl includes: Prepared by chlorinating the metallic silver film in an acidic solution environment; or The Ag / AgCl slurry is coated on the base electrode to prepare it.

7. The electrochemical water quality microsensor according to claim 2, characterized in that: The detection working electrode, the common counter electrode and the common reference electrode form a micro electrochemical three-electrode system, which can perform electrochemical scanning to achieve identification and detection of pollutants in water; and The pH control electrode, the common counter electrode and the common reference electrode form an electrochemical pH control system, which performs electrochemical constant current and / or constant voltage scanning to maintain the hydrolysis reaction in the specific area of ​​the thin layer detection cavity, so as to realize the control of the pH value of the solution in the detection area of ​​the detection working electrode.

8. The electrochemical water quality microsensor according to any one of claims 1 to 7, characterized in that: The material of the substrate includes one of silicon or glass. When the material of the substrate is silicon, an insulating film is grown on the surface of the silicon. The material of the insulating film includes silicon oxide and silicon nitride. The material of the pH control electrode includes gold; The material of the common counter electrode includes gold; The material of the detection working electrode is related to the type of pollutants to be detected, and the material of the detection working electrode includes one of gold, platinum, silver, copper or carbon.

9. The electrochemical water quality microsensor according to claim 8, characterized in that: The surfaces of the pH regulating electrode, the common counter electrode, the detection working electrode and the common reference electrode are covered with an insulating layer, and the material of the insulating layer includes one of silicon oxide, silicon nitride, a composite film composed of silicon oxide and silicon nitride, or a photoresist.

10. The electrochemical water quality microsensor according to any one of claims 1 to 7, characterized in that: Include at least one of the following features: The thin layer detection cavity structure is prepared by using PDMS material and a demoulding process; The thin layer detection cavity structure and the substrate are packaged and formed by an oxygen plasma bonding process; and The preparation method of the detection working electrode, the pH control electrode, the common counter electrode and the common reference electrode comprises a magnetron sputtering method or an electron beam evaporation method.

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