CN112903774A - All-solid-state pH sensor for deep sea and preparation method thereof - Google Patents
All-solid-state pH sensor for deep sea and preparation method thereof Download PDFInfo
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Images
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/302—Electrodes, e.g. test electrodes; Half-cells pH sensitive, e.g. quinhydron, antimony or hydrogen electrodes
-
- B22F1/0003—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/02—Compacting only
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/10—Oxidising
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/301—Reference electrodes
Abstract
The invention relates to an all-solid-state pH sensor and a preparation method thereof, belonging to the technical field of pH sensors. The all-solid-state pH sensor comprises an electrode protection shell (7), wherein the electrode protection shell (7) internally comprises a pH sensor fixed by a packaging material (5) and a sealing and packaging material (8) for sealing, and the lower end of the electrode protection shell is provided with a protective cover (9); the pH sensor comprises an all-solid-state iridium oxide pH response electrode (3) and an all-solid-state Ag/AgX reference electrode (4), wherein the all-solid-state iridium oxide pH response electrode (3) comprises an iridium metal core (2) and an iridium oxide film (1) wrapped on the outer surface of the iridium metal core (2); the iridium oxide film (1) is prepared and generated by adopting a high-temperature thermal oxidation method; the all-solid-state iridium oxide pH response electrode (3) and the all-solid-state Ag/AgX reference electrode (4) are respectively connected with a lead (6). The sensor device has the characteristics of high pressure resistance, high stability, small size and the like, and can be applied to a deep-sea high-pressure environment.
Description
Technical Field
The invention belongs to the technical field of sensor analysis and test, and particularly relates to an all-solid-state pH sensor for deep sea and a preparation method thereofx) The electrode adopts a high-pressure forming method to prepare an all-solid Ag/AgX reference electrode and a packaging technology thereof.
Background
The traditional pH composite glass electrode has the problems of high impedance, easy breakage and the like, is difficult to be applied to extreme environments such as deep sea and strong corrosive systems, and blocks the pH value detection of the extreme environments.
IrOxAs H+The response electrode has the characteristics of wide response range, high response speed and the like, is suitable for being used as an electrode core of the pH response electrode, and the optimization of the preparation method of the response electrode is a research hotspot all the time. The traditional reference electrode is a silver/silver chloride electrode, a saturated potassium chloride solution is arranged in the tube body, and the tube body is mostly made of glass materials and is difficult to apply to a high-pressure environment; the silver wire with the silver chloride coating is used as a reference, the coating is easy to fall off in the using process, the service life is short, the stability is poor, and the silver wire is more difficult to apply to high-pressure environments such as deep sea and the like.
In addition, the problem of packaging the electrode in high-voltage environments such as deep sea is also a great problem in limiting the application of the conventional electrode in high-voltage environments such as deep sea. Exploration of suitable IrOx H+The response electrode and the reference electrode are prepared by the preparation method, the pH electrode and the reference electrode which have stable performance and are suitable for deep sea environment are prepared, the electrodes are packaged by adopting a proper method, the sensor is applied to high-voltage environments such as deep sea environment and the like, the technical problem of overcoming is always solved by researchers, and the method has important practical significance。
Disclosure of Invention
Aiming at the technical problems, the invention provides an all-solid-state pH sensor for deep sea and a preparation method thereof. The all-solid-state pH sensor for the deep sea provided by the invention has good stability, can be applied to testing under complex environments such as high pressure, strong corrosion and the like, ensures the accuracy of pH measurement, and overcomes the defects of the traditional pH electrode.
The invention is realized by the following technical scheme:
an all-solid-state pH sensor comprises an electrode protection shell, wherein the inside of the electrode protection shell comprises a pH sensor fixed by packaging materials and sealing and packaging materials for sealing;
the pH sensor comprises an all-solid-state iridium oxide pH response electrode (3) and an all-solid-state Ag/AgX reference electrode, and when the all-solid-state iridium oxide pH response electrode and the all-solid-state Ag/AgX reference electrode are packaged in the sealing material, one part of the all-solid-state iridium oxide pH response electrode and one part of the all-solid-state Ag/AgX reference electrode exposed outside are used for pH sensing;
the all-solid-state iridium oxide pH response electrode comprises an iridium metal core and an iridium oxide film wrapped on the outer surface of the iridium metal core; the iridium oxide film is prepared and generated by adopting a high-temperature thermal oxidation method;
the all-solid-state iridium oxide pH response electrode and the all-solid-state Ag/AgX reference electrode are respectively connected with a lead.
Further, a protective cover is arranged at the lower end of the all-solid-state iridium oxide pH response electrode.
Furthermore, the electrode protection shell is made of high-strength metal or high-strength non-metal materials; including stainless steel, titanium alloys, polytetrafluoroethylene or polyvinyl chloride.
Further, the packaging material and the sealing and packaging material adopt silicon rubber or epoxy resin.
The sizes of the pH response electrode and the reference electrode can be changed within a certain range, a microelectrode (less than or equal to 100 mu m) is manufactured when the size is small, and a common electrode (more than 100 mu m) is manufactured when the size is larger.
Further, the all-solid-state iridium oxide pH response electrode has a wide pH response range, the pH response range is 0-14, and the response sensitivity is the near Nernst response of 40-70 mV/pH.
A method of making an all-solid pH sensor, the method comprising:
preparing an all-solid-state iridium oxide pH response electrode by adopting a high-temperature thermal oxidation method;
preparing an all-solid-state Ag/AgX reference electrode by adopting a high-pressure forming method;
the solid-sealed all-solid-state iridium oxide pH response electrode and the all-solid-state Ag/AgX reference electrode are vertically fixed above a desktop in an inverted manner, and the tops of electrode cores are basically in the same horizontal plane;
sleeving the electrode protection shell and fixing, injecting a fixed sealing material and a packaging material for sealing, standing until the sealing material is completely sealed to obtain the all-solid-state pH sensor.
Further, the method for preparing the full-solid iridium oxide pH response electrode by adopting a high-temperature thermal oxidation method comprises the following steps:
(1) cleaning and pretreating the surface of the iridium metal core;
(2) soaking the pretreated iridium metal core in an alkali solution to activate the metal surface;
(3) heating the iridium metal core treated in the step (2) at a constant temperature in a high-temperature environment for a period of time, then air-cooling or taking out the iridium metal core, and immediately quenching the iridium metal core to generate an iridium oxide film on the surface of the iridium metal core to prepare and obtain a pH response electrode core;
(4) soaking the pH response electrode core in the step (3) in deionized water for a period of time;
(5) and connecting one end of the soaked pH response electrode core with a lead, and sealing in a packaging material to generate the all-solid-state iridium oxide pH response electrode.
The all-solid-state iridium oxide pH response electrode prepared by the high-temperature thermal oxidation method can obtain an iridium oxide surface induction film with the thickness of micron level, wherein H can be realized+High proportion of responsive membrane components, less defective components, uniform membrane component particles, H+Large response specific surface area, convenient preparation, good stability and high sensitivity (50-60mV/pH, which is a Nenernst response).
Further, in the step (1), the pretreatment is to perform ultrasonic cleaning in concentrated hydrochloric acid solution and then perform ultrasonic cleaning in deionized water, wherein the cleaning time is longer than 15 min;
in the step (2), the adopted alkali solution is concentrated alkali (5mol/L sodium hydroxide solution), and the soaking time is at least 24 hours;
in the step (3), the high-temperature treatment conditions are as follows: the temperature is 700 ℃ and 900 ℃, and the heating time is 30min-2 h; the quenching medium is deionized water;
in the step (4), the soaking time is more than 2 days.
Further, the all-solid-state Ag/AgX reference electrode is prepared by a high-pressure forming method, and the method comprises the following steps:
(1) fully grinding a certain amount of pure Ag powder and AgX powder, and uniformly mixing;
(2) placing the uniformly mixed powder in a die of a powder tablet machine, performing compression molding on the powder tablet machine under certain pressure, maintaining the pressure for a period of time, and demolding by using a demolding die to prepare a cylindrical Ag/AgX reference electrode;
(4) welding the Ag/AgX reference electrode lead, reserving a working surface, and fixedly sealing the welding spot and other surfaces with packaging materials;
(4) polishing the sealed electrode step by using abrasive paper, scrubbing the surface by using absolute ethyl alcohol and washing the surface by using distilled water, and then activating the electrode in dilute hydrochloric acid for a period of time for later use; and obtaining the all-solid-state Ag/AgX reference electrode.
Further, in the step (1), the purity of the pure Ag powder is more than or equal to 99.99 percent, and the pure Ag powder is sieved by a 100-mesh sieve; the AgX powder is AgCl and AgBr mixed powder; according to the mass percentage, the percentage content of the silver chloride is 70-90 percent, and the sum of the percentage content of the silver chloride and the percentage content of the silver chloride is 100 percent.
The AgX powder, AgCl and AgBr are in proper proportion, all components are uniformly dispersed and the particle size of the powder is small after being fully ground by a grinding machine, and the prepared all-solid-state reference electrode is high in response speed and good in potential stability.
Compared with the prior art, the invention has the advantages that:
in the all-solid-state pH sensor provided by the invention, the all-solid-state oxygenIridium oxide (IrO)x) The pH electrode is provided with IrO prepared by a high-temperature thermal oxidation methodxA surface film, the film layer having an iridium oxide surface-sensitive film of micron-scale thickness, wherein H can be achieved+High proportion of responsive membrane components, less defective components, uniform membrane component particles, H+The response specific surface area is large; thus, the electrode has a wide pH response range (pH0-14) with response sensitivity of a near Nernst response (40-70 mV/pH). The all-solid-state Ag/AgX reference electrode is prepared by a high-pressure forming method, the ratio of AgCl to AgBr is proper, all components are uniformly dispersed and the particle size of powder is small after the components are fully ground by a grinding machine; therefore, the electrode has a fast response speed and good long-term stability. The all-solid-state iridium oxide electrode and the all-solid-state reference electrode are high-pressure resistant and corrosion resistant, and are hermetically packaged by pressure-resistant and corrosion-resistant materials and a shell.
The all-solid-state pH sensor prepared by the invention can be applied to the determination of the pH of a strong corrosive system in deep water and deep sea high-pressure environments. The method provided by the invention couples the all-solid-state iridium/iridium oxide pH electrode which responds to hydrogen ions and the all-solid-state silver/silver halide reference electrode which is stable under high pressure through a packaging technology, and the sensor device has the characteristics of sensitive response, high pressure resistance, high stability, small volume, convenience in installation and carrying and the like. The preparation method of the all-solid-state pH sensor provided by the invention is simple and feasible, good in practicability, low in cost and wide in application range.
Drawings
Fig. 1 is a schematic structural diagram of an all-solid-state pH sensor provided in an embodiment of the present invention;
FIG. 2 is a short term stability curve for an all-solid Ag/AgX reference electrode provided in accordance with an embodiment of the present invention;
FIG. 3a is a graph of potential (E) versus time for an all-solid Ag/AgX reference electrode provided in accordance with an embodiment of the present invention in 3 wt.% NaCl solutions at different pH;
FIG. 3b is a potential-pH response curve for an all-solid Ag/AgX reference electrode provided by an embodiment of the present invention;
FIG. 4a is a graph of potential (E) versus time for an all-solid Ag/AgX reference electrode in NaCl solutions of different concentrations provided by an example of the present invention;
FIG. 4b is a Nernst response curve for an all solid state Ag/AgX reference electrode provided by an embodiment of the present invention;
FIG. 5 shows an embodiment of the present invention providing all-solid Ir/IrOxNernst response curve of pH electrode;
fig. 6 is a graph illustrating an application of the all-solid-state sensor according to the embodiment of the present invention in seawater.
Reference numerals: 1-IrO (IrO)x) The method comprises the following steps of preparing a film, 2-iridium metal core, 3-all-solid-state iridium oxide pH response electrode, 4-all-solid-state Ag/AgX reference electrode, 5-packaging material, 6-lead, 7-electrode protection shell, 8-sealing and packaging material and 9-protection cover.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
On the contrary, the invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, certain specific details are set forth in order to provide a better understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details.
Aiming at the technical problem that the traditional pH electrode is not suitable for a high-pressure and strong-corrosion deep sea environment, the embodiment of the invention provides an all-solid-state pH sensor for deep sea, which is a bipolar pH sensor and is shown in figure 1: the method comprises the following steps:
an electrode shield case 7, the inside of the electrode shield case 7 including a pH sensor fixed by an encapsulating material 5 and a sealing and encapsulating material 8 for sealing;
the pH sensor comprises an all-solid-state iridium oxide pH response electrode 3 and an all-solid-state Ag/AgX reference electrode 4, wherein the all-solid-state iridium oxide pH response electrode 3 and the all-solid-state Ag/AgX reference electrode 4 are respectively connected with a wire 6;
the all-solid-state iridium oxide pH response electrode 3 comprises an iridium metal core 2 and a layer of iridium oxide film 1 wrapping the outer surface of the iridium metal core 2; the iridium oxide film 1 is prepared and generated by adopting a high-temperature thermal oxidation method; the lower end of the all-solid iridium oxide pH response electrode 3 is provided with a protective cover.
Specifically, when the all-solid-state iridium oxide pH response electrode 3 and the all-solid-state Ag/AgX reference electrode 4 are packaged in the sealing material 5, a part of the all-solid-state iridium oxide pH response electrode exposed outside is used for pH sensing.
The sizes of the all-solid-state iridium oxide pH response electrode 3 and the all-solid-state Ag/AgX reference electrode 4 can be changed within a certain range, and a microelectrode is manufactured when the size is small, and a common electrode is manufactured when the size is large.
The lead 6 is a copper, silver, aluminum lead or other material with good conductivity.
The electrode protection shell 7 is made of high-strength metal or high-strength non-metal materials; including stainless steel, titanium alloys or similar metallic or non-metallic materials such as polytetrafluoroethylene, polyvinyl chloride, and the like.
The sealing material 5 and the sealing and packaging material 8 are made of materials with sealing functions, such as silicon rubber or epoxy resin.
The embodiment of the invention provides a preparation method of an all-solid-state pH sensor for deep sea, which comprises the following steps:
preparing an all-solid-state iridium oxide pH response electrode by adopting a high-temperature thermal oxidation method;
preparing an all-solid-state Ag/AgX reference electrode by adopting a high-pressure forming method;
the solid-sealed all-solid-state iridium oxide pH response electrode and the all-solid-state Ag/AgX reference electrode are vertically fixed above a desktop in an inverted manner, and the tops of electrode cores are basically in the same horizontal plane;
sleeving the electrode protection shell and fixing, injecting a fixed sealing material and a packaging material for sealing, standing until the sealing material is completely sealed to obtain the all-solid-state pH sensor.
In this embodiment, the preparation of the all-solid iridium oxide pH-responsive electrode by using a high-temperature thermal oxidation method includes the following steps:
(1) cleaning and pretreating the surface of the iridium metal core; the pretreatment is that ultrasonic cleaning is firstly carried out in concentrated hydrochloric acid solution (more than 1mol/L), and then ultrasonic cleaning is carried out in deionized water, and the cleaning time is more than 15 min;
(2) soaking the pretreated iridium metal core in an alkali solution to activate the metal surface; the adopted alkali solution is concentrated alkali (5mol/L), and the soaking time is at least 24 h;
(3) heating the iridium metal core treated in the step (2) at a constant temperature in a high-temperature environment for a period of time, then air-cooling or taking out the iridium metal core, and immediately quenching the iridium metal core to generate an iridium oxide film on the surface of the iridium metal core to prepare and obtain a pH response electrode core; the high-temperature treatment conditions are as follows: the temperature is 700 ℃ and 900 ℃, and the heating time is 30min-2 h; the quenching medium is deionized water;
(4) soaking the pH response electrode core in the step (3) in deionized water for a period of time; the soaking time is more than 2 days;
(5) and connecting one end of the soaked pH response electrode core with a lead, and sealing in a packaging material to generate the all-solid-state iridium oxide pH response electrode.
In the present embodiment, it is preferred that,
the method for preparing the all-solid-state Ag/AgX reference electrode by adopting a high-pressure forming method comprises the following steps:
(1) fully grinding a certain amount of pure Ag powder and AgX powder, and uniformly mixing; the purity of the pure Ag powder is more than or equal to 99.99 percent, and the pure Ag powder is sieved by a 100-mesh sieve; the AgX powder is mixed powder of AgCl and AgBr, the percentage content of silver chloride is 70-90% by mass percent, and the sum of the percentage content of the two substances is 100%.
(2) Placing the uniformly mixed powder in a die of a powder tablet machine, performing compression molding on the powder tablet machine under certain pressure, maintaining the pressure for a period of time, and demolding by using a demolding die to prepare a cylindrical Ag/AgX reference electrode;
(4) welding the Ag/AgX reference electrode lead, reserving a working surface, and fixedly sealing the welding spot and other surfaces with packaging materials;
(4) polishing the sealed electrode step by using abrasive paper, scrubbing the surface by using absolute ethyl alcohol and washing the surface by using distilled water, and then activating the electrode in dilute hydrochloric acid for a period of time for later use; and obtaining the all-solid-state Ag/AgX reference electrode.
In specific application, the pH sensor can directly and conveniently measure the pH value of the seawater with various pressures.
The application and effect of the deep-sea all-solid-state pH sensor provided by the embodiment of the present invention are further described as follows:
the electrochemical workstation is used for carrying out performance characterization on the all-solid-state Ag/AgX reference electrode prepared by the powder high-pressure forming method to obtain figures 2, 3a-3b and 4a-4 b. In a three-electrode system (a saturated silver/silver chloride electrode is a reference electrode, a platinum sheet is a counter electrode, and the all-solid-state Ag/AgX reference electrode prepared in the above example is a working electrode), the ambient temperature is 22 ± 3 ℃, the potential (E) -time curve of the electrode is measured in a 3 wt.% NaCl solution, and the curve shown in fig. 2 can be obtained by plotting E against the soaking time. The potential (E) -time curves of the electrodes were measured in 3 wt.% NaCl solutions at different pH, and plotting E against pH, the curves shown in fig. 3 were obtained. Measuring the potential (E) -time curve of the electrode in NaCl solutions of different concentrations, comparing E with Cl-Plotting the logarithm of the activity yields the curve shown in FIG. 4. As shown in FIGS. 2, 3a-3b and 4a-4b, the all-solid-state Ag/AgX reference electrode prepared by the invention has better stability, the change of pH value has no influence on the potential of the electrode, and the all-solid-state Ag/AgX reference electrode has better Nernst response characteristic.
In the three-electrode system (the saturated silver/silver chloride electrode is used as a reference electrode, the platinum sheet is used as a counter electrode, and the all-solid-state Ir/IrO prepared in the above embodiment is usedxThe electrode was the working electrode), the potential (E) -time (t) curves of the electrode were measured in buffer at different pH values (pH0-14) at the same ambient temperature, the stable potential of the electrode in solution at each pH value was plotted against pH, and the curves were fitted to give the curves shown in fig. 5. For prepared Ir/IrOxThe pH electrode system was tested for application performance in seawater, and the curve shown in FIG. 6 was obtained by potential-pH conversion. As shown in FIGS. 5 and 6, the all-solid Ir/IrO prepared by the present inventionxThe electrode response range is wide, the response can be carried out in the pH range of 0-14, the electrode response sensitivity is 54.24mV/pH is near Nernst response (Nernst response theoretical value 59.16 mV/p)H) (ii) a And the application test result of the electrode in seawater shows that the electrode has high response speed, stable performance and all-solid Ir/IrOxThe electrode has good applicability.
Claims (10)
1. An all-solid-state pH sensor is characterized by comprising an electrode protection shell (7), wherein the inside of the electrode protection shell (7) comprises a pH sensor fixed by a packaging material (5) and a sealing and packaging material (8) for sealing;
the pH sensor comprises an all-solid-state iridium oxide pH response electrode (3) and an all-solid-state Ag/AgX reference electrode (4), and when the all-solid-state iridium oxide pH response electrode (3) and the all-solid-state Ag/AgX reference electrode (4) are packaged in the sealing material (5), one part of the exposed part is used for pH sensing;
the all-solid-state iridium oxide pH response electrode (3) comprises an iridium metal core (2) and a layer of iridium oxide film (1) wrapped on the outer surface of the iridium metal core (2); the iridium oxide film (1) is prepared and generated by adopting a high-temperature thermal oxidation method;
the all-solid-state iridium oxide pH response electrode (3) and the all-solid-state Ag/AgX reference electrode (4) are respectively connected with a lead (6).
2. The all-solid pH sensor according to claim 1, wherein a protective cover (9) is provided at the lower end of the all-solid iridium oxide pH responsive electrode (3).
3. The all-solid-state pH sensor according to claim 1, wherein the electrode protection housing (7) is made of a high-strength metal or a high-strength non-metal material; including stainless steel, titanium alloys, polytetrafluoroethylene or polyvinyl chloride.
4. The all-solid-state pH sensor according to claim 1, wherein the encapsulating material (5) and the sealing and encapsulating material (8) are silicone rubber or epoxy resin.
5. The all-solid-state pH sensor according to claim 1, wherein the all-solid-state iridium oxide pH responsive electrode (3) has a wide pH response range, a pH response range of 0-14, and a response sensitivity of a near nernst response of 40-70 mV/pH.
6. A method of making an all-solid pH sensor, the method comprising:
preparing an all-solid-state iridium oxide pH response electrode by adopting a high-temperature thermal oxidation method;
preparing an all-solid-state Ag/AgX reference electrode by adopting a high-pressure forming method;
the solid-sealed all-solid-state iridium oxide pH response electrode and the all-solid-state Ag/AgX reference electrode are vertically fixed above a desktop in an inverted manner, and the tops of electrode cores are basically in the same horizontal plane;
sleeving the electrode protection shell and fixing, injecting a fixed sealing material and a packaging material for sealing, standing until the sealing material is completely sealed to obtain the all-solid-state pH sensor.
7. The method for preparing the all-solid-state pH sensor according to claim 6, wherein the all-solid-state iridium oxide pH response electrode is prepared by a high-temperature thermal oxidation method, and comprises the following steps:
(1) cleaning and pretreating the surface of the iridium metal core;
(2) soaking the pretreated iridium metal core in an alkali solution to activate the metal surface;
(3) heating the iridium metal core treated in the step (2) at a constant temperature in a high-temperature environment for a period of time, then air-cooling or taking out the iridium metal core, and immediately quenching the iridium metal core to generate an iridium oxide film on the surface of the iridium metal core to prepare and obtain a pH response electrode core;
(4) soaking the pH response electrode core in the step (3) in deionized water for a period of time;
(5) and connecting one end of the soaked pH response electrode core with a lead, and sealing in a packaging material to generate the all-solid-state iridium oxide pH response electrode.
8. The method for preparing an all-solid-state pH sensor according to claim 7, wherein in the step (1), the pretreatment comprises performing ultrasonic cleaning in concentrated hydrochloric acid solution of more than 1mol/L, and then performing ultrasonic cleaning in deionized water for more than 15 min;
in the step (2), the adopted alkali solution is concentrated alkali, and the soaking time is at least 24 hours;
in the step (3), the high-temperature treatment conditions are as follows: the temperature is 700 ℃ and 900 ℃, and the heating time is 30min-2 h; the quenching medium is deionized water;
in the step (4), the soaking time is more than 2 days.
9. The method for preparing an all-solid-state pH sensor according to claim 6, wherein the all-solid-state Ag/AgX reference electrode is prepared by a high pressure forming method, and comprises the following steps:
(1) fully grinding a certain amount of pure Ag powder and AgX powder, and uniformly mixing;
(2) placing the uniformly mixed powder in a die of a powder tablet machine, performing compression molding on the powder tablet machine under certain pressure, maintaining the pressure for a period of time, and demolding by using a demolding die to prepare a cylindrical Ag/AgX reference electrode;
(4) welding the Ag/AgX reference electrode lead, reserving a working surface, and fixedly sealing the welding spot and other surfaces with packaging materials;
(4) polishing the sealed electrode step by using abrasive paper, scrubbing the surface by using absolute ethyl alcohol and washing the surface by using distilled water, and then activating the electrode in dilute hydrochloric acid for a period of time for later use; and obtaining the all-solid-state Ag/AgX reference electrode.
10. The preparation method of the all-solid-state pH sensor according to claim 9, wherein in the step (1), the purity of the pure Ag powder is more than or equal to 99.99%, and the pure Ag powder is sieved by a 100-mesh sieve; the AgX powder is AgCl and AgBr mixed powder; according to the mass percentage, the percentage content of the silver chloride is 70-90 percent, and the sum of the percentage content of the silver chloride and the percentage content of the silver chloride is 100 percent.
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