CN210572087U

CN210572087U - Residual chlorine sensor based on electrochemical principle

Info

Publication number: CN210572087U
Application number: CN201920875230.0U
Authority: CN
Inventors: 张志峰
Original assignee: Chengdu Wanzhong One Core Biotechnology Co ltd
Current assignee: Chengdu Wanzhong One Core Biotechnology Co ltd
Priority date: 2019-06-12
Filing date: 2019-06-12
Publication date: 2020-05-19
Anticipated expiration: 2029-06-12

Abstract

The utility model relates to a chlorine residue sensor based on electrochemistry principle, chlorine residue sensor include working circuit and a plurality of electrode, the electrode material that has at least an adoption in a plurality of electrode includes metal silicide. The utility model discloses unexpected discovery of people, the material that constitutes by suitable metal silicide is the chlorine residue detection electrode material of very ideal, by the electrode that it was made, not only can be used for the detection of chlorine residue, and sensitivity is high, and this electrode still can keep very stable electrochemistry specific after taking place electrochemical reaction under the environment that contains chlorine residue moreover, and the electric treatment performance is strong in durability, and the electrode is difficult for ageing, therefore, the utility model discloses a sensor can effectively solve the needs that traditional electrochemistry detected chlorine residue and frequently change electrode, the difficult problem of awkward. Moreover, the utility model discloses a raw materials cost that the sensor adopted is showing lower, and can large-scale production.

Description

Residual chlorine sensor based on electrochemical principle

Technical Field

The utility model belongs to the technical field of the sensor, concretely relates to chlorine residue sensor based on electrochemistry principle.

Background

In the prior art, in the field of residual chlorine sensors, N-diethyl-p-phenylenediamine (DPD) spectrophotometry and electrochemical methods are commonly used for measuring residual chlorine.

The principle of DPD spectrophotometry is that DPD reacts rapidly with free residual chlorine in water to produce a red compound, and the absorbance of the red compound is measured by spectrophotometry at 515nm to measure residual chlorine. The spectrophotometric method has complex operation and poor real-time detection, and the residual chlorine detection result is interfered when various substances (such as manganese oxide, bromine, potassium iodide, copper and the like) exist in water, and in addition, the problems of unstable residual chlorine measurement result and low accuracy caused by easy color change of a reagent and the like exist.

The electrochemical method is to detect residual chlorine by using a sensor based on an electrochemical principle. The electrodes of prior art sensors for residual chlorine detection are typically metal (e.g., platinum) or metal alloy electrodes. For a long time, people find in practice that the electrode has weak durability of electric treatment performance, is easy to age, cannot realize long-term stable detection of residual chlorine, and must frequently replace the electrode, so that the use cost is very high, and a lot of inconvenience is caused to the use. Since the discovery of problems has been carried out for thirty years, the related problems have not yet been effectively solved. In addition, the conventional electrode is difficult to realize mass production, and the cost of raw materials is high.

Disclosure of Invention

The invention aims to provide an improved residual chlorine sensor in order to overcome the defects of a residual chlorine sensor based on an electrochemical principle in the prior art.

In order to achieve the above purpose, the utility model adopts the technical scheme that:

a residual chlorine sensor based on an electrochemical principle comprises a working circuit and a plurality of electrodes, wherein at least one of the electrodes adopts an electrode material comprising metal silicide.

Further, at least one of the plurality of electrodes is a working electrode and a counter electrode, and the electrode material adopted by the working electrode and/or the counter electrode comprises metal silicide.

Furthermore, the electrode material adopted by at least one of the electrodes is of a two-layer structure or a three-layer structure, when the electrode material is of a two-layer structure, one layer is made of the metal silicide, and the other layer is made of silicon; when the electrode material is a three-layer structure, the middle layer is made of silicon, and the outer layers positioned on two sides of the middle layer are made of the metal silicide.

Furthermore, in the two-layer structure or the three-layer structure, the thickness of the layer made of the metal silicide is 10-500 nanometers, and the thickness of the layer made of the silicon is 0.1-1.5 millimeters.

Furthermore, the two-layer structure or the three-layer structure is formed by taking a silicon substrate as a substrate, depositing a metal layer and then performing heat treatment.

The deposition method adopted by the deposition is a thermal evaporation deposition method, an electron beam evaporation deposition method, a magnetron sputtering deposition method, a chemical plating deposition method, an electroplating deposition method and the like; the heat treatment method is to adopt a rapid annealing furnace (RTA, RTP), a tubular annealing furnace, a hot plate or a vacuum annealing furnace to heat to 100-600 ℃ for 10-200 minutes under the condition that the atmosphere is nitrogen or vacuum.

Preferably, the thickness of the silicon substrate is 0.1-1.5 mm, and the thickness of the deposited metal layer is 10-500 nm.

The silicon substrate is made of polycrystalline silicon or doped monocrystalline silicon, and the resistivity of the silicon substrate is 0.01-10 omega cm.

More preferably, the thickness of the deposited metal layer is 30-150 nm.

Further, the metal in the metal silicide is selected from transition metals.

Preferably, the metal in the metal silicide is one or more selected from platinum, nickel, titanium, cobalt, palladium and tungsten.

Further, the metal silicide is one or more of platinum silicide, nickel silicide, titanium silicide, cobalt silicide, palladium silicide or tungsten silicide.

In some specific implementation aspects, the silicon substrate can be a silicon wafer with a polished or non-polished surface, and a silicon substrate with a micro-nano structure can also be selected as the substrate.

When a silicon substrate with a micro-nano structure is selected as a substrate, the silicon substrate is prepared by the following method: coating photoresist on the surface of a silicon substrate to form a photoresist layer, exposing the photoresist layer through a mask corresponding to a micro-nano structure graph by using ultraviolet light beams, obtaining a micro-nano geometric graph which is the same as the mask graph on the photoresist layer after developing, and manufacturing a required micro-structure on the silicon substrate through plasma dry etching to obtain the silicon substrate with the micro-nano structure.

If a silicon substrate with a micro-nano structure is selected as the silicon substrate, the prepared metal silicide electrode also has the micro-nano structure.

Further, the electrode materials adopted by one, two or three of the plurality of electrodes respectively comprise the metal silicide.

Further, one of the plurality of electrodes is a reference electrode that does not contain a metal silicide.

Preferably, the reference electrode is a silver/silver chloride electrode.

Furthermore, the residual chlorine sensor also comprises an auxiliary connecting mechanism which is used for conducting the electrode made of the electrode material containing metal silicide with the working circuit.

Furthermore, the auxiliary connecting mechanism comprises a shell, a circuit board positioned in the shell and a lead used for conducting the circuit board with the working circuit, one end of an electrode made of an electrode material containing metal silicide is in contact with the circuit board to be electrically conducted, the other end of the electrode material is a free end, and the free end is positioned outside the shell.

In some embodiments, the auxiliary connecting mechanism further includes a metal spring piece disposed in the housing and having two ends respectively pressed on the circuit board and the electrode made of the electrode material containing metal silicide, so that the circuit board and the electrode made of the electrode material containing metal silicide can be electrically connected.

In some embodiments, the residual chlorine sensor further includes a potting adhesive filled in the housing to ensure waterproofing of the circuit inside the housing.

In some embodiments, a circuit is disposed on the circuit board within the housing, and the circuit has a detection purpose in addition to conducting the electrode and the working circuit.

The residual chlorine sensor based on the electrochemical principle can be used for detecting residual chlorine content, pH value, fluorine ion content, potassium ion content and calcium ion content in a system, oxidation-reduction potential of the system, conductivity of the system or total amount of soluble solids in the system.

Further, the system is an aqueous system or a battery electrolyte system.

Further, the water system includes industrial process water, domestic water, seawater, sewage, swimming pool water, and natural water.

In the present invention, the residual chlorine refers to free chlorine in the system. If the system is water, it refers to the free chlorine in the water.

Because of the application of the technical scheme, compared with the prior art, the utility model has the following advantages:

the inventor of the invention has discovered unexpectedly that the material formed by suitable metal silicide is a very ideal electrode material for detecting residual chlorine, and the electrode made of the material not only can be used for detecting residual chlorine, has high sensitivity, but also can keep very stable electrochemistry special after electrochemical reaction under the environment containing residual chlorine, has strong durability of electric treatment performance and difficult aging of the electrode, therefore, the sensor of the utility model can effectively solve the difficult problems of frequent replacement of the electrode and inconvenient use in the traditional electrochemical detection of residual chlorine. Moreover, the utility model discloses a raw materials cost that the sensor adopted is showing lower, and can large-scale production.

Drawings

Fig. 1 is a schematic structural view of a metal silicide electrode of embodiment 1;

fig. 2 is a schematic front cross-sectional view of a metal silicide-based electrode module of example 2;

FIG. 3 is a schematic cross-sectional side view of the metal silicide-based electrode module of example 2;

FIGS. 4(a), (b) are schematic diagrams of a potentiostat circuit and an I-V conversion circuit, respectively, of the residual chlorine sensor of example 3;

FIG. 5 is a schematic view showing the structure of a residual chlorine sensor according to example 3;

FIG. 6 is a schematic structural diagram of a homemade reference electrode module used in the residual chlorine sensor of example 3;

FIG. 7 is a graph showing the results of measuring the open circuit voltage between a self-made reference electrode module and a commercial reference electrode used in the residual chlorine sensor of example 3;

FIG. 8 is a graph showing the relationship between the sensor output signal and the operating time in the residual chlorine detection in the residual chlorine sensor of example 3;

FIG. 9 is a graph showing the relationship between the output signal of the sensor and the calibration value of free chlorine obtained by performing a free chlorine content test on the residual chlorine sensor of example 3 in a water body with pH of 6.86 at 23 ℃;

FIG. 10 shows the results of five consecutive days of the chlorine residue sensor of example 3 in a water body having pH of 6.86 and a free chlorine content of 2mg/L at 23 deg.C for one time per day;

FIG. 11 is a graph of free chlorine content measurements versus free chlorine calibration using 5 residual chlorine sensors of example 3 in a water body having a pH of 6.86 at 23 deg.C;

FIG. 12 is a graph of the relationship between the sensor measurements and free chlorine calibration for the residual chlorine sensor of example 3 in water of different pH;

FIG. 13 is a graph showing the relationship between the measured value of residual chlorine and the temperature of a specific water sample measured by the residual chlorine sensor of example 3;

FIG. 14 shows examples 3 (A)RC_T-RC₂₃)/RC₂₃Plotting T-23;

FIGS. 15(a), (b) are schematic circuit diagrams of two voltage followers, U4A and U4B, respectively, of the residual chlorine sensor of example 4;

FIG. 16 is a schematic structural view of a residual chlorine sensor of example 4;

FIG. 17 is a schematic diagram showing the relationship between the output signal of the sensor and the pH calibration value obtained by testing the residual chlorine sensor of example 4 in the test solutions with different pH values at 23 ℃;

FIG. 18 is a graphical representation of the relationship of sensor measurements to pH calibration using 3 residual chlorine sensors of example 4, tested for pH in an environment at 23 ℃;

FIG. 19 is a schematic diagram showing the relationship between the output signal of the sensor and the ORP calibration value obtained by testing the residual chlorine sensor of example 4 in a water body with different oxidation-reduction potentials at 23 ℃;

FIGS. 20(a) and (b) are schematic circuit diagrams of an I-V conversion circuit and a voltage follower, respectively, of the residual chlorine sensor of example 5;

FIG. 21 is a schematic structural view of a residual chlorine sensor of example 5;

fig. 22 is a graph showing the relationship between the sensor output signal and the TDS calibration value obtained from the test of the residual chlorine sensor of example 5 in a water body with different TDSs in an environment of 23 ℃.

In the figure: 1. a metal silicide electrode; 101. a silicon substrate; 102. a metal silicide layer; 2. a housing; 3. a circuit board; 4. a metal spring piece; 5. pouring a sealant; 6. a wire; 7. a housing; 8. a silver/silver chloride electrode; 9. a silver wire; 10. agar gels containing saturated potassium chloride; 11. a piece of porous material; 12. waterproof glue; 13. a metal silicide based electrode module; 14. a reference electrode module; 15. connecting the circuit board externally; 16. and (6) liquid to be detected.

Detailed Description

As introduced in the background art, the electrode in the prior art is usually made of metal or metal alloy, and the cost of the electrode made of metal or metal alloy is higher, so that when the electrode is used for a residual chlorine sensor, the cost of the sensor is greatly increased, and the electrode is not suitable for large-scale production. In addition, the residual chlorine sensor prepared by the traditional electrochemical electrode (the electrode material is metal or metal alloy), because the residual chlorine has strong corrosive action, the traditional electrochemical electrode can react with the residual chlorine to generate chemical reaction, the electrochemical characteristics of the traditional electrode are influenced, the durability of the electrical treatment performance is weak, and the stable detection cannot be realized, which is a technical problem that cannot be solved in the field for two thirty years. The inventor of the application prepares novel silicide conductive ceramic from the semiconductor technology through the transboundary, it has fine electrode characteristic to discover unexpectedly that metal silicide has, be used for preparing the electrode with this metal silicide, this electrode still can keep very stable electrochemistry specific after taking place electrochemical reaction under the chlorine residue environment, the electrical treatment performance is strong in durability, the electrode is difficult for ageing, be used for chlorine residue sensor with this metal silicide electrode, the detection chlorine residue that can be stable, the technical problem that traditional electrode can not stably detect chlorine residue has been broken through.

The invention is further described with reference to the drawings and the specific embodiments.

Example 1

In the present embodiment, a metal silicide electrode 1 is provided, and referring to fig. 1, the metal silicide electrode 1 has a two-layer structure, wherein one layer is a silicon substrate 101, and the other layer is a metal silicide layer 102 formed on the silicon substrate 101.

Wherein the thickness of the metal silicide layer is 10-500 nm, and the thickness of the silicon substrate is 0.1-1.5 mm.

The metal silicide is one or more of platinum silicide, nickel silicide, titanium silicide, cobalt silicide, palladium silicide or tungsten silicide.

The metal silicide electrode 1 is prepared by the following method:

(1) depositing a metal layer on a silicon substrate;

(2) placing the workpiece prepared in the step (1) in an oxygen-free environment for heat treatment so that silicon and metal react to generate metal silicide;

(3) and (3) cutting the workpiece prepared in the step (2) to prepare the metal silicide electrode.

Wherein:

in the step (1), the step (c),

The thickness of the silicon substrate is 0.2 mm-1.5 mm, and particularly 0.5 mm can be selected.

In the step (2),

the metal is selected from transition metals, preferably, the metal is one or more selected from platinum, nickel, titanium, cobalt, palladium and tungsten. Specifically, platinum and tungsten can be selected.

The thickness of the metal layer is 10-500 nm. The thickness of the metal layer is preferably 30-150 nm. Specifically 50 nm and 100 nm.

The deposition method is thermal evaporation deposition, electron beam evaporation deposition, magnetron sputtering deposition, chemical plating deposition, electroplating deposition and the like.

The heat treatment method is to heat treat the mixture for 10 to 200 minutes by adopting a rapid annealing furnace (RTA, RTP), a tubular annealing furnace, a hot plate or a vacuum annealing furnace at the temperature of between 100 and 600 ℃ under the condition of nitrogen or vacuum.

Example 2

The electrode module based on metal silicide provided by the embodiment, referring to fig. 2-3, includes a metal silicide electrode 1, a housing 2, a circuit board 3 fixedly disposed in the housing 2, and a conducting wire 6 for electrically conducting the circuit board 3 with an external circuit, wherein one end of the metal silicide electrode 1 is in contact with the circuit board 3, and the other end is a free end, and the free end is located outside the housing 2.

This electrode module based on metal silicide still including set up in casing 2 and both ends press respectively to establish on circuit board 3 and metal silicide electrode 1 and make circuit board 3 and metal silicide electrode 1 metal spring leaf 4 that can the electric conduction, and fill potting compound 5 in casing 2 to guarantee the waterproof of casing 2 internal circuit.

The circuit board 3 in the housing 2 is provided with a circuit which can conduct the metal silicide electrode 1 and an external circuit, and has a detection purpose. Or the circuit arranged on the circuit board 3 in the shell 2 is only used for conducting the metal silicide electrode 1 with the external circuit.

Wherein, the shell 2 is made of hard plastics, and the materials include but are not limited to ABS engineering plastics, PE, PS and the like;

the metal spring piece 4 can be made of copper, glass copper, stainless steel and the like;

the potting adhesive 5 may be an AB epoxy resin or the like.

In this example, the structure of the metal silicide electrode 1 is the same as that of example 1, and the metal leaf spring 4 is pressed on the metal silicide layer 102 of the metal silicide electrode 1.

The preparation of the electrode module based on the metal silicide is as follows:

the upper end of the shell 2 is provided with a wire hole and a glue filling hole, the lower end of the shell is provided with a metal silicide electrode 1 socket, the other end of the wire 6 penetrates out of the shell 2 from the wire hole and extends to the outside of the shell 2, and the shell is connected with an external circuit according to further needs and used as an output signal and/or a power supply wire. One end of the metal silicide electrode 1 enters the shell 2 through an insertion hole at the lower end part of the shell 2, the metal silicide electrode 1 is required to be ensured to be in contact with the metal spring piece 4, the elasticity of the metal spring piece 4 provides pressure to fix the position of the metal silicide electrode 1 and ensure that the electric conduction condition between the metal silicide electrode 1 and the circuit board 3 is good; the casing 2 is filled with a potting adhesive 5 to ensure the water resistance of the internal circuit.

Example 3

The embodiment provides a residual chlorine sensor which is designed according to an amperometric determination principle, adopts a three-electrode working mode and is used for detecting the content of certain substances to be detected which are easy to generate oxidation-reduction reaction in a water body. The three electrodes are respectively a Working Electrode (WE), a Reference Electrode (RE) and a Counter Electrode (CE). When the residual chlorine sensor works, a constant voltage is applied to two ends of the working electrode and the reference electrode so as to ensure that the working electrode maintains a stable potential. Under the action of electrocatalysis, the object to be detected generates electrocatalysis reaction on the working electrode, and the current passing through the working electrode is related to the concentration of the object to be detected, so that the content of the object to be detected can be obtained by measuring the current on the working electrode.

The circuit design of the residual chlorine sensor is shown in fig. 4. The working principle of the circuit is as follows: the circuit consists of a constant potential rectifier circuit and an I-V conversion circuit. U4D and the accessory circuit form a potentiostat circuit, the potential of the reference electrode RE is applied through RC _ REF _ N to provide a stable working voltage to the working electrode WE, and U4C and the accessory circuit form an I-V conversion circuit for ad sampling through a port p 2.2. The role of RE is to provide a stable electrode potential during the measurement process to ensure that the potential of the working electrode remains stable during the measurement process.

Referring to fig. 5, the residual chlorine sensor includes a working circuit, 2 electrode modules 13 based on metal silicide, 1 reference electrode module 14 and an external circuit board 15, the working circuit is integrated on the external circuit board 15, and the 2 electrode modules 13 based on metal silicide and the 1 reference electrode module 14 are respectively electrically connected to the external circuit board 15.

In this example, the circuit design shown in fig. 4 is integrated on the external circuit board 15, and the circuit on the circuit board 3 of the metal silicide-based electrode module 13 is only used for conducting the metal silicide electrode 1 and the working circuit. In other embodiments, the circuit on the circuit board 3 of the metal silicide-based electrode module 13 has a detection purpose besides conducting the metal silicide electrode 1 and the working circuit.

In this example, the structure of the electrode module 13 based on metal silicide is designed as in example 2.

In this example, one of the metal silicide electrodes of the 2 metal silicide-based electrode modules 13 is used as a Working Electrode (WE), the other is used as a Counter Electrode (CE), and the reference electrode module 14 is used as a Reference Electrode (RE).

In this example, the reference electrode module may use a commercial reference electrode, such as a commercially available silver/silver chloride reference electrode. A self-made reference electrode module may also be used.

Referring to fig. 6, the homemade reference electrode module comprises a housing 7 with a containing cavity, a silver/silver chloride electrode 8 arranged in the housing 7, a silver lead 9 extending from the silver/silver chloride electrode 8, a porous material piece 11 arranged in the housing 7 and having one end penetrating one end of the housing 7 and extending out of the housing 7, and an agar gel 10 filled in the housing 7 and containing saturated potassium chloride, wherein one end of the silver lead 9 penetrates the other end of the housing 7 and extends out of the housing 7. Wherein, the shell 7 is made of hard plastics, and the materials include but are not limited to ABS engineering plastics, PE, PS and the like; the shape of the inner part of the shell is not limited, and the volume of the shell is 1-50 cubic centimeters; the porous material piece 11 is a fiber or a porous ceramic.

The shell 7 can be a shell and an upper cover matched with the shell, the upper cover is provided with a wire guide hole and a liquid injection hole, a silver/silver chloride electrode 8 made of silver wires is arranged in the shell, and the extended silver wires extend out of the shell through the wire guide hole on the upper cover. The lower end of the shell is provided with a liquid connecting through hole, a section of porous material piece 11 with proper size is inserted into the connecting hole, one end of the porous material piece 11 extends into the shell, the function of the porous material piece is to enable the gel in the shell to be in ion communication with the external solution to be detected and limit the diffusion speed of chloride ions in the shell to the external solution to be detected; in the shell, agar (1-5%) gel containing saturated potassium chloride is filled among the silver/silver chloride electrode 8, the porous material piece 11 and the inner wall of the shell; the upper cover is also provided with a liquid injection hole, and hot liquid sol can be injected into the shell through the liquid injection hole to fill the inner space. The space between the shell and the upper cover, the wire hole and the liquid injection hole are sealed by waterproof glue 12.

The manufacturing method of the silver/silver chloride electrode 8 comprises the following steps: winding a silver wire having a diameter of 0.1 to 1.0 mm into a spiral shape having an inner diameter of 2.0 to 10 mm by using a winding machine to increase a surface area per unit volume; soaking in a sodium hypochlorite solution with the concentration of 5% for 12 hours to obtain a silver/silver chloride electrode; the electrode was repeatedly pulled up five times in 12 ml of a tetrahydrofuran solution containing 0.01g of sodium chloride and 0.4g of polyvinyl chloride, dried at room temperature for 48 hours, then repeatedly pulled up five times in a 5% Nafion solution, then treated at 80 ℃ for 1 hour, and finally taken out and cooled to room temperature, thus obtaining a silver/silver chloride electrode.

In this example, ABS engineering plastic is used as the housing, the inner dimension of the housing is 50 × 20 × 10 mm, and the thickness of the housing is 2 mm; the diameter of the silver wire used is 0.2 mm, and the inner diameter of the spiral shape formed by winding is 2.5 mm; the porous material piece 11 is a fiber strip; the mass fraction of agar in the agar gel was 3%.

The fibers of the reference electrode module were soaked in tap water and the open circuit voltage between the reference electrode module and a commercial reference electrode (Ag/AgCl reference electrode) was measured. The results of the measurements are plotted against the soaking time as shown in fig. 7. As a result, the potential shift after 190 hours was found to be 3.85mV (relative to a commercial Ag/AgCl reference electrode). The self-made reference electrode module has stable potential and can be used as a reference electrode.

When the residual chlorine sensor provided in this embodiment is used to detect a liquid to be detected (for example, the liquid to be detected is water), referring to fig. 5, the metal silicide electrodes exposed outside on the two electrode modules 13 based on metal silicide used as the working electrode and the counter electrode and the fiber strips of the reference electrode module 14 are soaked in the liquid to be detected 16, and the liquid to be detected 16 is used as an electrolyte solution to form a circuit loop through conduction. The current passing through the working electrode can be converted into an output signal, and the acquisition frequency can be set. Because the circuit design has a potential correction function, the working electrode can keep a stable potential, so that the signal of the module can keep a good linear relation with the content of the object to be measured of water, and a linear fitting equation can be obtained. During measurement operation, the sensor operates in water to obtain an output signal, and the linear fitting equation is used for calculation to obtain the content of the substance to be measured in the water. In actual application, the influence of temperature and pH is also considered, and correction is carried out according to actual conditions.

The residual chlorine sensor provided by the embodiment can be used for detecting the content of some substances to be detected which are easy to generate oxidation-reduction reaction in water, such as residual chlorine content in water, such as tap water, sewage, swimming pool water and natural water. Different detection objects have different residual chlorine concentration ranges (Ministry of health of the people' S republic of China, sanitary standard of domestic drinking water [ S ]. GB 5749-2006, 2006:3-6), for example, after the pipe network domestic drinking water is disinfected by chlorine for 30 minutes, the content of free residual chlorine in the water is not lower than 0.3 mg/L; the standard value of the free residual chlorine in the water of the artificial swimming pool is 0.3 mg/L-0.5 mg/L; the content of free residual chlorine on the surface of the tableware disinfected by the chlorine-containing decontamination agent is less than 0.3 mg/L; the measuring range of the residual chlorine in the industrial circulating cooling water is 0.03 mg/L-2.5 mg/L. In this design, the residual chlorine measurement range is set to 0-8mg/L, which is merely an example to illustrate the function of the sensor. In actual use, the detection range of the sensor needs to be set in consideration of the requirements of a specific detection object.

The principle of residual chlorine detection is as follows: when chlorine gas is dissolved in water, hypochlorous acid, which is a weak acid and partially decomposed into hydrogen ions and hypochlorite ions, is generated through a series of reactions, and oxidation-reduction reaction of hypochlorous acid occurs on the surface of the electrode (formula (1) and formula (2)). During detection, a constant voltage is applied to the two ends of the working electrode and the reference electrode to keep the potential of the working electrode constant, and under the action of electrocatalysis, HOCl and OCl^-Electrocatalytic reaction is generated on the PtSi working electrode, and the electrode signal and the content of the substance to be detected in the water body form a linear relation.

The reaction that occurs when chlorine dissolves in water is as follows:

the reaction equation on the working electrode for residual chlorine detection is as follows:

HOCl+2e→Cl^-+OH^-formula (1)

OCl^-+H₂O+2e→Cl^-+2OH^-Formula (2)

The chlorine residue sensor of the present example was used to detect chlorine residue in water

Specifically, a platinum silicide electrode is used as a working electrode and a counter electrode, and the platinum silicide electrode is prepared as follows: a P-type silicon wafer with a polished single surface and a thickness of 0.5 mm is used as a substrate, 50 nanometers of platinum is plated on the polished surface by an electron beam evaporation deposition method, then heat treatment is carried out by a tubular annealing furnace in a nitrogen atmosphere to enable silicon and platinum to react to generate platinum silicide, and then a silicon substrate with the platinum silicide formed on the surface is cut into 3 multiplied by 9.5 multiplied by 0.5 mm by a blade to obtain a platinum silicide electrode, wherein the heat treatment temperature is 400 ℃, and the heat treatment time is 60 minutes.

In the electrode module based on metal silicide, the area of platinum silicide electrode exposed outside the module is 3 x 5 mm; the shell is made of ABS engineering plastics; the metal spring piece is made of copper; the pouring sealant is AB epoxy resin; the dimensions of the electrode socket on the housing are: 3.2X 0.7 mm.

Two electrode modules which are provided with platinum silicide electrodes and are based on metal silicide are respectively used as a working electrode and a counter electrode in a circuit, and a reference electrode module is used as a reference electrode in the circuit and is connected to the circuit designed as shown in figure 4.

When the electrode module is used, the platinum silicide electrode and the fiber strip of the reference electrode module, which are exposed outside on the two electrode modules based on the metal silicide and are used as the working electrode and the counter electrode, are soaked in a water body to be detected. During measurement operation, a constant voltage is applied across the working electrode and the reference electrode to maintain the working electrode at a potential of +350mV (vs reference electrode, i.e., RC _ REF _ P-RC _ REF _ N-350 mV), and then the sensor output signal is read and the acquisition frequency can be set.

The following tests were carried out on the properties of the residual chlorine sensor of this example when used for detecting residual chlorine in water:

1. the residual chlorine sensor of this example was used at pH 6.86 in an environment of 23 ℃ and contained various free chlorine contents (all free chlorine contents were measured by HACH Pocket Colorimeter)^TMII (CHLORINE) portable residual CHLORINE meter for calibration) in the water body, the relationship between the output signal of the residual CHLORINE sensor and the operation time is shown in fig. 8.

As can be seen from FIG. 8, the output signals obtained by the residual chlorine sensor in the water with different free chlorine contents are obviously distinguished, and the signals are stable after 60 seconds of operation. In order to collect stable signals and improve the accuracy, in the test, the process of each test of the residual chlorine sensor is as follows: and electrifying the residual chlorine sensor to operate for 120 seconds, collecting 10 data per second, and calculating an average value by adopting the data of the last 10 seconds as an output signal finally collected in the test.

2. In an environment of 23 ℃, a free chlorine content test was performed in a water body having a pH of 6.86 using a residual chlorine sensor, and the relationship between the obtained sensor output signal and the free chlorine calibration value was obtained, as shown in fig. 9.

As can be seen from FIG. 9, in the water with pH of 6.86 at 23 deg.C, the output signal of the residual chlorine sensor and the free chlorine in the water were in the range of 0-8mg/LThe chlorine content was fitted linearly with the equation-6.6 x +869.6, R²A better linearity is seen at 0.9951. And substituting the output signal of the sensor into calculation through the linear fitting equation to obtain the residual chlorine measurement value of the sensor.

3. The multiple residual chlorine measurements and errors of the residual chlorine sensor are shown in table 1.

TABLE 1

Calibration value of residual chlorine (mg/L)	Residual chlorine measurement (mg/L)	Absolute measurement deviation (mg/L)
			0.05412	0	0.05412
1.66644	2	0.33356
			0.04379	0	0.04379
5.75828	6	0.24172
			0.04366	0	0.04366
2.21797	2	0.21797
			0.03462	0	0.03462
1.95444	2	0.04556

As can be seen from Table 1, the absolute measurement deviation is 0.33356mg/L at the maximum, indicating that the error of the sensor is small.

4. And (3) carrying out stability test on the residual chlorine sensor: the residual chlorine sensor was continuously immersed in a water body having a pH of 6.86 and a free chlorine content of 2mg/L in an environment of 23 ℃, and the results of the test were shown in fig. 10 and are obtained from fig. 10 once a day for five consecutive days, with Std of 8.14%. The stability of the residual chlorine sensor in the test time is good.

5. And (3) carrying out consistency test on the residual chlorine sensor: in an environment of 23 ℃, 5 residual chlorine sensors are tested in a water body with pH of 6.86, the relationship between the measured values of the sensors and the calibration values of the free chlorine is shown in fig. 11, and the results show that the residual chlorine sensors are good in consistency.

6. Evaluation of ion selectivity of the residual chlorine sensor: in an environment of 23 ℃, the responses of the residual chlorine sensor to various possible interfering substances in the water body (the response value unit is mg/L, and the response current value is converted into the corresponding residual chlorine content through a residual chlorine linear fitting equation) are shown in table 2.

TABLE 2

Mg referred to above²⁺、Na⁺、K⁺、Ca²⁺、Cu²⁺、NH₄ ⁺、Zn²⁺、Cl^-、SO₄ ^2-、NO₂ ^-The experimental amount of ions exceeds the concentration range of common household water. Therefore, if the using scene is domestic water, the interference of the ions on the residual chlorine sensor can be ignored.

7. The relationship between the measured value of the residual chlorine sensor and the calibration value of the free chlorine in water bodies with different pH values is shown in figure 12.

The result shows that the output signal of the sensor is related to the pH value of the water body to be measured. When the pH value of the water body to be measured is 5-8, the measuring result is not influenced by the pH value. For detection of tap water and swimming pool water, the pH is within the range of 5-8, and compensation is not needed.

8. The residual chlorine measurements of the sensor in a particular water sample (free chlorine calibration held constant at 8 mg/L) are plotted versus temperature, as shown in FIG. 13.

It can be seen that the measured value of residual chlorine is greatly influenced by temperature, and the relationship between the measured value and the measured value is approximate to linearity. The temperature compensation can be performed as follows: t is the current temperature (DEG C), RC_TAs measured by residual chlorine in temperature T, RC₂₃The measured value of residual chlorine obtained at the same concentration in 23 ℃ was measured using the same sensor. Will (RC)_T-RC₂₃)/RC₂₃Plotting T-23 and performing linear fitting to obtain the fitting formula y ═ kx. Wherein k is the temperature correction coefficient. The temperature correction of the residual chlorine sensor can be performed using the following equation:

RC_C＝RC_M/[1+k(T-23)]

wherein RC_CFor temperature correction of the residual chlorine concentration using a sensor, RC_MThe measured value of the sensor before temperature correction.

In the embodiment, first, (RC)_T-RC₂₃)/RC₂₃T-23 (. degree. C.) is plotted as shown in FIG. 14. And performing linear fitting to obtain a fitting formula y ═ kx. Temperature ofCorrection factor k 0.03745 deg.C^-1. The measured values RC of the sensors before correction of the respective temperatures_MCarry-over into formula RC_C＝RC_M/[1+k(T-23)]And obtaining the residual chlorine concentration after temperature correction.

Example 4

The present embodiment provides a residual chlorine sensor designed based on the principle of potentiometry, which measures the activity (or concentration) of a substance to be measured using the relationship between the electrode potential and the activity (or concentration, etc.) of an ion in a solution. The electrochemical cell is based on measuring the electromotive force of the cell, and the chemical cell is composed of electrolyte solution as the liquid to be measured, two electrodes inserted in the electrolyte solution, one is an indicating electrode whose electrode potential has a quantitative relation with the activity (or concentration, etc.) of the liquid to be measured, and the other is a reference electrode whose potential is stable and unchanged.

The circuit design of the residual chlorine sensor is shown in FIG. 15. The working principle of the circuit is as follows: the residual chlorine sensor consists of two voltage followers, namely U4A and U4B, in the embodiment, U4B is used as a power supply module of the reference electrode, and voltage is supplied to the reference electrode through OUT2 (OUT 2 is 0V in ORP application, and OUT2 is 1V in pH application). U4A acts as a buffer to provide readings to the AD module. OUT is connected with the indicating electrode and is output to the AD module through p 2.3.

Referring to fig. 16, the residual chlorine sensor includes a working circuit, 1 metal silicide-based

electrode module

13, 1 reference electrode module 14, and an external circuit board 15, the working circuit is integrated on the external circuit board 15, and the 1 metal silicide-based electrode module 13 and the 1 reference electrode module 14 are electrically connected to the external circuit board 15, respectively. In this example, the circuit design shown in fig. 15 is integrated on the external circuit board 15, and the circuit on the circuit board 3 of the metal silicide-based electrode module 13 is only used for conducting the metal silicide electrode 1 and the working circuit. In other embodiments, the circuit on the circuit board 3 of the metal silicide-based electrode module 13 has a detection purpose besides conducting the metal silicide electrode 1 and the working circuit.

In this example, the metal silicide electrodes of the 1 metal silicide-based electrode module 13 are used as the indicator electrodes, and the reference electrode module 14 is used as the reference electrode.

In this example, the reference electrode module 14 used in the sensor is the same as that used in example 3.

When the residual chlorine sensor of this embodiment is used to detect a liquid to be detected, as shown in fig. 16, a metal silicide electrode exposed outside on the electrode module 13 based on a metal silicide used as an indicator electrode and a fiber strip of the reference electrode module 14 are soaked in the liquid to be detected 16 (a water body to be detected), the liquid to be detected is used as an electrolyte solution, the reference electrode module 14 can provide a stable and unchangeable potential, a quantitative relationship exists between an electromotive force of the electrode module based on a metal silicide used as an indicator electrode and a content of a substance to be detected, and a potential difference between the electrode module based on a metal silicide and the reference electrode module can be converted into an output signal through a sensor circuit. Therefore, the output signal of the residual chlorine sensor in the liquid 16 to be measured is calculated through a fitting equation, and the content of the substance to be measured can be obtained. In actual application, the influence of the test environment is also considered, and correction is carried out according to actual conditions.

The residual chlorine sensor of the embodiment can be used for detecting the content of various ions, including but not limited to hydrogen ions (i.e. pH value), chloride ions, fluoride ions, potassium ions, and calcium ions, and can also be used for detecting the oxidation-reduction potential (ORP) of the liquid to be detected.

The residual chlorine sensor of the embodiment is used for detecting the pH value in water

The detection principle of the tungsten silicide used as the electrode material of the indicating electrode is as follows:

tungsten atoms on the surface of the tungsten silicide are oxidized to form a tungsten oxide layer, and the solubility of tungsten oxide in water is low. When the tungsten silicide electrode is soaked in water, tungsten oxide on the surface of the electrode is saturated with water and undergoes the following hydrolysis reaction to generate tungsten ions:

the tungsten ions on the surface of the electrode have a tendency to acquire electrons which are reduced to tungsten atoms:

therefore, a potential difference is formed between the surface of the tungsten silicide electrode and the interface of the aqueous solution. According to the nernst formula:

E＝E₀+RT/nF*ln[Mⁿ⁺]

wherein E₀Is the standard potential of the electrode, R is the gas constant, T is the temperature, F is the Faraday constant, T is the absolute temperature value, n is the number of transmitted electrons, [ M ]ⁿ⁺]Is the concentration of the ions. Then the potential difference E and the interface W⁶⁺The ion concentrations are related as follows:

E＝E₀+RT/6F*ln[W⁶⁺]

when equilibrium is reached, different concentrations of tungsten ions will cause the tungsten silicide electrodes to have different electrode potentials. Because tungsten oxide is poorly soluble in water, its solubility is related to the pH of water, and there are:

E＝E₀-0.059pH

wherein the unit of the potential is V. The potential difference E can be obtained by measuring the open circuit voltage between the tungsten silicide electrode and the reference electrode, and thus the pH value of the solution.

Specifically, a tungsten silicide electrode was used as an indicator electrode, and the tungsten silicide electrode was prepared as follows: a P-type silicon wafer with a polished single surface and a thickness of 0.5 mm is used as a substrate, 100 nanometers of tungsten is plated on the polished surface by an electron beam evaporation deposition method, then silicon and tungsten are subjected to heat treatment in a nitrogen atmosphere by using a rapid annealing furnace (RTA) to react to generate tungsten silicide, and then a silicon substrate with the tungsten silicide formed on the surface is cut into 3 x 9.5 x 0.5 mm by using a blade to obtain a tungsten silicide electrode, wherein the heat treatment temperature is 400 ℃, and the heat treatment time is 10 minutes.

In the electrode module based on the metal silicide, the area of the tungsten silicide electrode exposed outside the electrode module is 3 multiplied by 5 mm; the shell is made of ABS engineering plastics; the metal spring piece is made of copper; the pouring sealant is AB epoxy resin; the dimensions of the electrode socket on the housing are: 3.2X 0.7 mm.

The metal silicide-based electrode module 13 equipped with a tungsten silicide electrode was used as an indicating electrode in the circuit, and the reference electrode module 14 was used as a reference electrode in the circuit, and was connected to a circuit designed as described in fig. 15.

When the electrode module is used, the tungsten silicide electrode exposed outside on the electrode module based on the metal silicide as the indicating electrode and the fiber strips of the reference electrode module are soaked in the water body to be detected. During measurement operation, the output signal of the sensor is collected through the circuit, and the collection frequency can be set. The process of each test of the sensor is as follows: the sensor is electrified and operated, the operation lasts for 10 seconds, 10 data are collected every second, and the average value of the data is calculated to be used as the output signal of the final collection of the test.

The following tests were conducted on the properties of the chlorine residue sensor of this example when used for detecting the pH value in water:

1. the residual chlorine sensor was tested in test solutions of different pH values (all calibrated using a mettler pH meter) in a 23 ℃ environment, and the relationship between the sensor output signal and the pH calibration value was obtained, as shown in fig. 17.

As can be seen from FIG. 17, in the environment of 23 deg.C, the output signals of the residual chlorine sensor obtained in water with different pH values are clearly distinguished. In the range of pH 5-9, the output signal of the sensor is linearly fitted with the pH value of the water body, and the equation is that y is-52.1175 x +10.1623, R²The linearity was found to be better at 0.9999. And substituting the output signal of the sensor into calculation through the linear fitting equation to obtain the pH value measured value of the sensor.

2. The multiple pH measurements and errors of the sensor are shown in table 3.

TABLE 3

As can be seen from table 3, the absolute measurement deviation is 0.17339 at the maximum, indicating that the error of the sensor is small.

3. Testing the consistency of the residual chlorine sensor: the pH test was performed using 3 residual chlorine sensors in a 23 ℃ environment, with the sensor measurements plotted against the pH calibration, as shown in figure 18. The results show that the consistency of the residual chlorine sensor is good.

The residual chlorine sensor of the embodiment is used for detecting ORP in water

A platinum silicide electrode is adopted as an ORP indicating electrode, and the detection principle is as follows:

an ORP indicating electrode is an electrode that can absorb or release electrons at the surface for potential measurement, while at the same time requiring chemical stability and resistance to chemical shock. The solution ORP can be obtained by measuring the potential difference between the ORP indicator electrode and the reference electrode. The sensor output signal is an output signal reflecting the open circuit voltage between the platinum silicide electrode and the reference electrode. Therefore, the output signal can have a good linear relation with the ORP of the liquid to be detected, a linear fitting equation can be obtained according to the linear relation, and the ORP of the liquid to be detected can be obtained by calculating through the linear fitting equation.

Specifically, a platinum silicide electrode was used as an indicator electrode, and the platinum silicide electrode was prepared as follows: a P-type silicon wafer with a polished single surface and a thickness of 0.5 mm is used as a substrate, a platinum 50 nm is plated on the polished surface by an electron beam evaporation method, then a tubular annealing furnace is used for carrying out heat treatment in a nitrogen atmosphere to enable silicon and platinum to react to generate platinum silicide, and then a blade is used for cutting the platinum silicide into 3 x 9.5 x 0.5 mm to obtain a platinum silicide electrode, wherein the heat treatment temperature is 400 ℃, and the heat treatment time is 60 minutes.

A metal silicide-based electrode module equipped with a platinum silicide electrode was used as an ORP indicating electrode in the circuit, and a reference electrode module was used as a reference electrode in the circuit, and was connected to the circuit designed as shown in FIG. 15.

When the electrode module is used, the platinum silicide electrode exposed outside on the electrode module based on the metal silicide serving as the ORP indicating electrode and the fiber strips of the reference electrode module are soaked in a water body to be measured. During measurement operation, the output signal of the sensor is collected through the circuit, and the collection frequency can be set. In this embodiment, the procedure of each test of the residual chlorine sensor is as follows: the sensor is electrified and operated, the operation lasts for 10 seconds, 10 data are collected every second, and the average value of the data is calculated to be used as the output signal of the final collection of the test.

The following tests were conducted on the various performances of the residual chlorine sensor of this example for detecting ORP in water:

1. in a 23 ℃ environment, a residual chlorine sensor was used to test in water with different oxidation-reduction potentials, and the relationship between the obtained sensor output signal and the ORP calibration value is shown in fig. 19.

As can be seen from FIG. 19, in the environment of 23 ℃, the output signals of the residual chlorine sensor obtained in the water bodies with different oxidation-reduction potentials are clearly distinguished. The output signal of the sensor is linearly fitted with the ORP value of the water body, and the equation is that y is 0.8682x +92.0617, R²A better linearity is seen at 0.9542. Through the linear fitting equation, the output signal of the sensor is substituted into calculation to obtain the ORP measurement value of the sensor.

Example 5

This example provides a residual chlorine sensor designed by resistance measurement, which uses two conductivity electrodes to measure the conductivity and Total Dissolved Solids (TDS) of industrial process water, domestic water, seawater, battery electrolytes, etc.

In this embodiment, the metal silicide electrodes of the two metal silicide-based electrode modules are immersed in the solution to be measured as conductivity electrodes, and the conductivity of the intermediate solution is measured by using an ac bridge method. The relative positions of two electrode modules based on metal silicide as conductivity electrodes are fixed, the two electrodes can be placed in parallel, and the metal layers are opposite; the two electrodes may also be placed in the same plane.

When the sensor is used, the metal silicide electrodes exposed outside on the electrode modules based on the metal silicide serving as the conductivity electrodes are soaked in a water body, alternating current is applied to two ends of the two electrode modules, the current value flowing through the electrodes is converted into an output signal of the sensor circuit, and the output signal has correlation with the conductivity of the water body, so that a linear fitting equation can be obtained. During measurement operation, the sensor operates in the liquid to be measured to obtain an output signal, and the conductivity of the liquid to be measured can be obtained through calculation by a linear fitting equation. In actual application, the influence of temperature and pH is also considered, and correction is carried out according to actual conditions.

The circuit design of the residual chlorine sensor is shown in fig. 20. The working principle of the circuit is as follows: in the design, U1A is an I-V conversion circuit connected to an ADC module through P1.6, and U1B forms a voltage follower. p2.7 is connected to the IDAC module, and a voltage signal of 0.5-1-0V-0.5V is applied to one side electrode through the IDAC module. Wherein the two conductivity electrodes are respectively connected with the pin 2 and the pin 7.

Referring to fig. 21, the residual chlorine sensor includes a working circuit, 2 electrode modules 13 based on metal silicide and an external circuit board 15, the working circuit is integrated on the external circuit board 15, and the 2 electrode modules 13 based on metal silicide are electrically connected to the external circuit board 15, respectively. In this example, the circuit shown in fig. 20 is integrated on the external circuit board 15, and the circuit on the circuit board 3 of the metal silicide-based electrode module 13 is used only for conducting the metal silicide electrode 1 and the working circuit. In other embodiments, the circuit on the circuit board 3 of the metal silicide-based electrode module 13 has a detection purpose besides conducting the metal silicide electrode 1 and the working circuit.

The residual chlorine sensor of this example was used to detect the Total Dissolved Solids (TDS) of an aqueous solution

There is a good correlation between Total Dissolved Solids (TDS) and conductivity of an aqueous solution, and for a typical body of water, there is the following relationship:

TDS(mg/L)＝α×K(ms)

therefore, when TDS measurement is performed using the residual chlorine sensor of the present embodiment, TDS of the solution can be calculated by the above formula (α is an empirical value).

Specifically, a platinum silicide electrode was used as the conductivity electrode, and the platinum silicide electrode was prepared as follows: a P-type silicon wafer with a polished single surface and a thickness of 0.5 mm is used as a substrate, 50 nanometers of platinum is plated on the polished surface by an electron beam evaporation deposition method, then heat treatment is carried out by a tubular annealing furnace in a nitrogen atmosphere to enable silicon and platinum to react to generate platinum silicide, and then a silicon substrate with the platinum silicide formed on the surface is cut into 3 multiplied by 9.5 multiplied by 0.5 mm by a blade to obtain a platinum silicide electrode, wherein the heat treatment temperature is 400 ℃, and the heat treatment time is 60 minutes.

In the electrode module based on metal silicide, the area of platinum silicide electrode exposed outside the electrode module is 3 x 5 mm; the positions of the two electrodes are positioned on the same plane, and the distance between the two electrodes is 3 mm; the shell is made of ABS engineering plastics; the metal spring piece is made of copper; the pouring sealant is AB epoxy resin; the dimensions of the electrode socket on the housing are: 3.2X 0.7 mm.

A metal silicide-based electrode module equipped with a platinum silicide electrode was connected as an in-circuit conductive electrode to a circuit designed as described in fig. 20.

When in use, the platinum silicide electrode exposed outside on the electrode module based on metal silicide as the conductivity electrode is soaked in the liquid 16 to be detected (water body to be detected), as shown in fig. 21. During measurement operation, the output signal of the sensor is collected through the circuit, and the collection frequency can be set. The process of each test of the sensor is as follows: the sensor is electrified and operated, the operation lasts for 10 seconds, 10 data are collected every second, and the average value of the data is calculated to be used as the output signal of the final collection of the test.

The following tests were conducted on the properties of the residual chlorine sensor of this example for detecting Total Dissolved Solids (TDS) in an aqueous solution:

1. in a 23 ℃ environment, a test was performed using a residual chlorine sensor in a body of water with different TDS, and the relationship of the obtained sensor output signal to the TDS calibration value is shown in fig. 22.

As can be seen from fig. 22, in the environment of 23 ℃, the output signals of the residual chlorine sensors obtained in the water bodies with different TDS are clearly distinguished. Sensor output signalThe equation is that the number is linearly fitted with the TDS of the water body, and the equation is that y is 1.037x +950.407, R²A better linearity is seen at 0.9992. Through the linear fitting equation, the TDS measured value of the sensor can be obtained by substituting the output signal of the sensor into calculation.

2. Multiple TDS measurements and errors of the sensor are shown in table 4.

TABLE 4

As can be seen from table 4, the relative error is a maximum of 3.4%, indicating that the error of the sensor is small.

It should be noted that, when a specific residual chlorine sensor is assembled, 2 electrode modules based on metal silicide and 1 reference electrode module may be assembled into one residual chlorine sensor, and then different operation modes (for example, an operation mode in which 2 electrode modules based on metal silicide and 1 reference electrode module simultaneously operate (for example, the three-electrode operation mode in embodiment 3), an operation mode in which 1 electrode module based on metal silicide and 1 reference electrode module simultaneously operate (for example, the operation mode in embodiment 4), and an operation mode in which 2 electrode modules based on metal silicide simultaneously operate (for example, the operation mode in embodiment 5)) may be switched at different times by designing a circuit, so that it may be achieved that 1 residual chlorine sensor may monitor multiple indexes of a water body. The above combination is only one combination of the present invention, and other combinations may be performed as needed.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, so as not to limit the protection scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims

1. A residual chlorine sensor based on electrochemical principle comprises a working circuit and a plurality of electrodes, and is characterized in that: the electrode material adopted by at least one of the plurality of electrodes comprises a metal silicide layer composed of metal silicide.

2. The electrochemical-based residual chlorine sensor according to claim 1, wherein: at least a working electrode and a counter electrode are arranged in the plurality of electrodes, and electrode materials adopted by the working electrode and/or the counter electrode comprise the metal silicide layer.

3. The electrochemical-based residual chlorine sensor according to claim 1 or 2, characterized in that: one of the plurality of electrodes is a reference electrode that does not include the metal silicide layer.

4. The electrochemical-based residual chlorine sensor according to claim 3, wherein: the reference electrode is a silver/silver chloride electrode.

5. The electrochemical-based residual chlorine sensor according to claim 1 or 2, characterized in that: when the electrode material is of a two-layer structure, one layer is composed of the metal silicide, and the other layer is composed of silicon; when the electrode material is a three-layer structure, the middle layer is made of silicon, and the outer layers positioned on two sides of the middle layer are made of the metal silicide.

6. The electrochemical-based residual chlorine sensor according to claim 5, wherein: in the two-layer structure or the three-layer structure, the thickness of the layer composed of the metal silicide is 10-500 nanometers, and the thickness of the layer composed of the silicon is 0.1-1.5 millimeters.

7. The electrochemical-based residual chlorine sensor according to claim 5, wherein: the two-layer structure or the three-layer structure is formed by depositing a metal layer on a silicon substrate and then performing heat treatment.

8. The electrochemical-based residual chlorine sensor according to claim 7, wherein: the thickness of the silicon substrate is 0.1-1.5 mm, and the thickness of the deposited metal layer is 10-500 nm.

9. The electrochemical-based residual chlorine sensor according to claim 1 or 2, characterized in that: the metal in the metal silicide is selected from transition metals.

10. The electrochemical-based residual chlorine sensor according to claim 9, wherein: the metal in the metal silicide is one or more selected from platinum, nickel, titanium, cobalt, palladium and tungsten.

11. The electrochemical-based residual chlorine sensor according to claim 1 or 2, characterized in that: the metal silicide is one or more of platinum silicide, nickel silicide, titanium silicide, cobalt silicide, palladium silicide or tungsten silicide.

12. The electrochemical-based residual chlorine sensor according to claim 1, wherein: the electrode material used for one, two or three of the plurality of electrodes respectively comprises the metal silicide layer.

13. The electrochemical-based residual chlorine sensor according to claim 1 or 2, characterized in that: the residual chlorine sensor also comprises an auxiliary connecting mechanism which is used for conducting the electrode of the electrode material containing the metal silicide layer with the working circuit.

14. The electrochemical-based residual chlorine sensor according to claim 13, wherein: the auxiliary connecting mechanism comprises a shell, a circuit board positioned in the shell and a lead used for conducting the circuit board and the working circuit, wherein one end of an electrode of the electrode material containing a metal silicide layer is in contact electrical conduction with the circuit board, the other end of the electrode material is a free end, and the free end is positioned outside the shell.

15. The electrochemical-based residual chlorine sensor according to claim 14, wherein: the auxiliary connecting mechanism further comprises a metal spring piece which is arranged in the shell, and two ends of the metal spring piece are respectively pressed on the circuit board and the electrode of the electrode material containing the metal silicide layer, so that the circuit board and the electrode of the electrode material containing the metal silicide layer can be electrically conducted.

16. The electrochemical-based residual chlorine sensor according to claim 14, wherein: the residual chlorine sensor also comprises pouring sealant filled in the shell to ensure the water resistance of the circuit in the shell.

17. The electrochemical-based residual chlorine sensor according to claim 14, wherein: the circuit board in the shell is provided with a circuit, and the circuit has detection application except for conducting the electrode and the working circuit.