Electrochemical sensor and method and device for detecting ion concentration

Abstract

The invention relates to an electrochemical sensor and a method and device for detecting ion concentration, the method comprises the following steps: determining an ion concentration determination function corresponding to an ion selective electrode of the electrochemical sensor, the ion concentration determination function comprising a relationship between an elastic coefficient and ion concentration; acquiring a first corresponding relation between the open-circuit voltage and time according to the change of the corresponding open-circuit voltage of the ion selective electrode in the to-be-detected solution within the preset time; fitting the first corresponding relation to determine a first fitting curve function; determining a numerical value of an elastic coefficient according to the first fitting curve function; and calculating the ion concentration of the solution to be detected according to the ion concentration determination function and the value of the elastic coefficient. According to the scheme of the invention, the ion concentration data can be quickly obtained without waiting for polarization completion.

Description

Technical Field

[0001] This application relates to the technical field of electrochemical sensors, and in particular, to an electrochemical sensor, a method and a device for detecting ion concentration. Background Art

[0002] Metal ions such as sodium, potassium, and calcium in water are important indicators in water quality detection. The concentration of these ions directly affects indicators such as the electrolyte balance, hardness, and conductivity of water, and has an important impact on many industries such as food processing, sports physiology, household life, and agricultural breeding. Rapid on-site detection of ions in water can promptly respond to water quality changes, support environmental management and decision-making, and cope with emergencies. In the water treatment industry, rapid on-site detection can form a feedback regulation closed-loop, improve water treatment accuracy, and enhance data real-time performance and display.

[0003] Currently, the main methods for rapid on-site ion detection include technologies such as surface plasmon resonance, fluorescence probes, and electrochemistry. Among them, electrochemistry technology is the most widely used. Electrochemical measurement mainly relies on ion-selective electrodes. The sensitive membrane on the ion-selective electrode has selective permeability to specific ions. When the ion passes through the membrane, a potential difference will be generated at the interface between the membrane and the solution. This potential difference has a logarithmic relationship with the concentration of ions in the solution. By measuring the potential difference between the two electrodes, quantitative analysis of ion concentration can be carried out. There is a polarization process at the initial stage of ion-selective electrode measurement. The polarization duration is usually from dozens of minutes to several hours. The ion-selective electrode needs to wait for the polarization to complete and enter the potential stable state before starting the concentration measurement. Therefore, the immediacy of on-site ion electrochemical rapid detection is affected.

[0004] The main reason for the polarization process is that the surface of the ion-selective electrode deviates from its theoretical value due to the imbalance of charge transfer reactions. This deviation is usually related to the charge accumulation on the electrode surface, resulting in the inconsistency between the actually measured potential and the potential predicted by the Nernst equation. In actual measurement, the potential polarization process cannot be avoided. Therefore, the on-site detection time is also difficult to effectively reduce, making it difficult to obtain ion concentration data in a short time. Summary of the Invention

[0005] Based on this, in view of the problems existing in the prior art, this application provides an electrochemical sensor and a solution for detecting ion concentration implemented by the electrochemical sensor, which can quickly obtain ion concentration data without waiting for the polarization to complete.

[0006] According to the first aspect of the present application, there is provided a method for detecting ion concentration using an electrochemical sensor, characterized by comprising:

[0007] Determine the ion concentration determination function corresponding to the ion-selective electrode of the electrochemical sensor, wherein the ion concentration determination function includes the relationship between the elastic coefficient and the ion concentration;

[0008] Obtain the first correspondence between the open-circuit voltage and time according to the change of the open-circuit voltage corresponding to the ion-selective electrode in the solution to be measured within a preset time;

[0009] Fit the first correspondence to determine the first fitting curve function;

[0010] Determine the value of the elastic coefficient according to the first fitting curve function; and

[0011] Calculate the ion concentration of the solution to be measured according to the ion concentration determination function and the value of the elastic coefficient.

[0012] According to the second aspect of the present application, there is provided an electrochemical sensor, characterized in that it includes:

[0013] A processing device for executing the method described in the first aspect.

[0014] According to the third aspect of the present application, there is provided a device for detecting ion concentration using an electrochemical sensor, characterized in that it includes:

[0015] A first determination module for determining the ion concentration determination function corresponding to the ion-selective electrode of the electrochemical sensor, wherein the ion concentration determination function includes the relationship between the elastic coefficient and the ion concentration;

[0016] An acquisition module for obtaining the first correspondence between the open-circuit voltage and time according to the change of the open-circuit voltage corresponding to the ion-selective electrode in the solution to be measured within a preset time,

[0017] A second determination module for fitting the first correspondence to determine the first fitting curve function;

[0018] A third determination module for determining the value of the elastic coefficient according to the first fitting curve function; and

[0019] A calculation module for calculating the ion concentration of the solution to be measured according to the ion concentration determination function and the value of the elastic coefficient.

[0020] The electrochemical sensor, method and device for detecting ion concentration provided by this application test the ion-selective electrode with a standard solution of a preset ion concentration to obtain an ion concentration determination function. During the measurement of the actual solution ion concentration, the ion concentration of the solution to be measured is determined through the ion concentration determination function, without waiting for polarization to complete, thereby achieving rapid acquisition of ion concentration data. The solution of this application is applicable to all potentiometric electrochemical sensors that measure ion concentration through an ion-selective membrane and is universal in the field of ion point-of-care testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without exceeding the scope protected by this application.

[0022] Figure 1 is a schematic diagram of a fitting curve fitting the open-circuit voltage and time relationship according to an embodiment of this application.

[0023] Figure 2 is a schematic diagram of an ion concentration determination function curve fitting the elastic coefficient and ion concentration relationship according to an embodiment of this application.

[0024] Figure 3 is a schematic flowchart of a method for detecting ion concentration using an electrochemical sensor according to an embodiment of this application.

[0025] Figure 4 is a schematic diagram of a device for detecting ion concentration using an electrochemical sensor according to an embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope protected by this application.

[0027] Throughout the specification and claims, terms may have nuances implied or suggested by the context rather than the explicitly stated meaning. Similarly, the phrases "in one embodiment" or "in some embodiments" used herein do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" used herein do not necessarily refer to different embodiments. The phrases "in one implementation" or "in some implementations" used herein do not necessarily refer to the same implementation, and the phrases "in another implementation" or "in other implementations" used herein do not necessarily refer to different implementations. For example, the claimed subject matter includes all or partial combinations of exemplary embodiments or implementations.

[0028] Generally speaking, terms can be understood at least in part from their use in the context. For example, terms such as "and", "or", "and / or" used herein can have multiple meanings, which can depend at least in part on the context in which these terms are used. Generally, "or" if used to relate a list, such as A, B, or C, means A, B, and C, herein used in the inclusive sense, as well as A, B, or C, herein used only in the exclusive sense. In addition, the terms "one or more" or "at least one" used herein can, at least in part, depend on the context, be used to describe any feature, structure, or property in the singular sense, or can be used to describe a combination of features, structures, and properties in the plural sense. Similarly, terms such as "a", "an", or "the", at least in part, depending on the context, can also be understood to convey singular or plural usage. In addition, also at least in part depending on the context, the terms "based on" or "determined by" can be understood not necessarily to imply a set of exclusive factors, but rather to allow for the existence of other factors that may not be explicitly described.

[0029] Generally speaking, the inventive concept of this application is as follows: testing an ion-selective electrode with standard solutions of multiple preset ion concentrations, recording the open-circuit voltage and the relationship between the open-circuit voltage and time, obtaining a first ion concentration determination function, and determining the elastic coefficient through the first ion concentration determination function; then, according to the relationship between the elastic coefficient and the ion concentration, fitting an ion concentration determination function. During the actual measurement of the ion concentration of the solution, record the open-circuit voltage and the relationship between the open-circuit voltage and time, obtain a second ion concentration determination function, determine the elastic coefficient obtained during the actual measurement process through the second ion concentration determination function, and finally, determine the ion concentration of the solution to be measured according to the ion concentration determination function and the elastic coefficient obtained during the actual measurement process.

[0030] In some embodiments, the electrochemical sensor adopts a two - electrode form, including an ion - selective electrode and a reference electrode, with an ion - selective membrane covering the surface of the ion - selective electrode. In one embodiment, the ion - selective electrode is a calcium ion electrode and the reference electrode is a silver chloride reference electrode. Those skilled in the art can understand that other two - electrode configurations can also be adopted, and the present application makes no limitation thereto.

[0031] In some embodiments, the ion - selective electrodes prepared from the same batch of membrane solution are sampled and tested to determine the polarization standard curve at various ion concentrations. For example, the calcium ion electrode is tested using calcium ion standard solutions with concentrations of 1 μM, 10 μM, 100 μM, and 1 mM respectively. An electrochemical workstation is used to record the open - circuit voltage change curve within a preset time (such as 50 seconds) after the calcium ion electrode contacts the solution. After each test, the electrode surface can be rinsed with deionized water and dried at room temperature. Those skilled in the art can understand that other concentrations, other types, and other numbers of standard solutions can also be used, and the preset time for the ion - selective electrode to contact the solution can be of any appropriate length, which all fall within the scope covered by the present application.

[0032] Figure 1 is a schematic diagram of a fitting curve fitting the relationship between the open - circuit voltage and time according to an embodiment of the present application. As Figure 1 shown, it includes four curves of the relationship between the open - circuit voltage and time. These curves are fitted to obtain the fitting curve and the fitting - curve function. In a specific embodiment, the fitting - curve function can adopt the form of a logarithmic function Y = alnX + b, where Y represents the open - circuit voltage, X represents the time, a is the elastic coefficient (or elastic value) of the fitting - curve function, and b is the intercept coefficient. As Figure 1 shown, corresponding to the four curves of the relationship between the open - circuit voltage and time, the values of the elastic coefficient a are - 4.85, - 8.67, - 14.53, and - 18.36 respectively.

[0033] Figure 2 is a schematic diagram of an ion - concentration determination function curve fitting the relationship between the fitting elastic coefficient and the ion concentration according to an embodiment of the present application. In some embodiments, after determining the ion concentrations of multiple standard solutions and the corresponding values of multiple elastic coefficients, the ion concentrations of multiple standard solutions and the corresponding values of multiple elastic coefficients are fitted to determine the ion - concentration determination function. In a specific embodiment, as Figure 2 shown, the function obtained by fitting the ion concentrations of multiple standard solutions and the corresponding values of multiple elastic coefficients is an exponential function.

[0034] In some embodiments, after determining the ion concentration determination function corresponding to the ion-selective electrode, when actually measuring a solution with an unknown concentration using the ion-selective electrode, the corresponding relationship between the open-circuit voltage and time can be obtained according to the change in the open-circuit voltage corresponding to the ion-selective electrode within a preset time in the solution to be measured. Then, the corresponding relationship is fitted to determine the fitting curve function; the value of the elastic coefficient is determined according to the fitting curve function; finally, the ion concentration of the solution to be measured is calculated according to the ion concentration determination function and the value of the elastic coefficient.

[0035] Based on the above description, according to one aspect of the present application, a method for detecting the ion concentration of an electrochemical sensor is provided. As Figure 3 shown, the method includes the following steps.

[0036] Step S301, determining the ion concentration determination function corresponding to the ion-selective electrode of the electrochemical sensor, where the ion concentration determination function includes the relationship between the elastic coefficient and the ion concentration;

[0037] Step S302, obtaining the first corresponding relationship between the open-circuit voltage and time according to the change in the open-circuit voltage corresponding to the ion-selective electrode within a preset time in the solution to be measured,

[0038] Step S303, fitting the first corresponding relationship to determine the first fitting curve function;

[0039] Step S304, determining the value of the elastic coefficient according to the first fitting curve function; and

[0040] Step S305, calculating the ion concentration of the solution to be measured according to the ion concentration determination function and the value of the elastic coefficient.

[0041] In some embodiments, in order to quickly measure the ion concentration, it is necessary to determine the ion concentration determination function reflecting the relationship between the elastic coefficient and the ion concentration, and it is also necessary to determine the open-circuit voltage change curve within a preset time after the ion-selective electrode contacts the solution and the first fitting curve function formed by fitting the curve, so as to determine the value of the elastic coefficient; finally, the ion concentration of the solution to be measured is calculated according to the ion concentration determination function and the value of the elastic coefficient.

[0042] It can be understood that step S301 and steps S302 - 304 can be executed successively or simultaneously, and the present application does not impose any restrictions on this.

[0043] For step S301 of determining the ion concentration determination function, in some alternative embodiments, it may include the following steps:

[0044] According to the change of the open-circuit voltage corresponding to the ion-selective electrode in solutions of multiple preset concentrations, a plurality of second corresponding relationships between the open-circuit voltage and time are correspondingly obtained;

[0045] Perform fitting on the plurality of second corresponding relationships to respectively obtain a plurality of second fitting curve functions;

[0046] Determine the values of a plurality of elastic coefficients respectively according to the plurality of second fitting curve functions; and

[0047] Perform fitting on the values of the plurality of elastic coefficients and their corresponding plurality of preset concentrations to determine the ion concentration determination function.

[0048] In some embodiments, the open-circuit voltage change of the electrode can be measured in solutions of multiple known concentrations, a plurality of corresponding relationships between the open-circuit voltage and time are determined, fitting is respectively performed on the plurality of corresponding relationships to obtain a plurality of fitting curve functions and the values of a plurality of elastic coefficients, and fitting is performed on the values of the plurality of elastic coefficients and the plurality of preset concentrations to determine the ion concentration determination function.

[0049] According to another aspect of the present application, a device for detecting the ion concentration of an electrochemical sensor is provided. As Figure 4 shown, the device includes: a first determination module 401, an acquisition module 402, a second determination module 403, a third determination module 404, and a calculation module 405. Among them, the first determination module 401 is used to determine the ion concentration determination function corresponding to the ion-selective electrode of the electrochemical sensor, wherein the ion concentration determination function includes the relationship between the elastic coefficient and the ion concentration; the acquisition module 402 is used to obtain the first corresponding relationship between the open-circuit voltage and time according to the change of the open-circuit voltage corresponding to the ion-selective electrode in the solution to be measured within a preset time, the second determination module 403 is used to perform fitting on the first corresponding relationship to determine the first fitting curve function; the third determination module 404 is used to determine the value of the elastic coefficient according to the first fitting curve function; the calculation module 405 is used to calculate the ion concentration of the solution to be measured according to the ion concentration determination function and the value of the elastic coefficient.

[0050] In some alternative embodiments, the first determination module 401 can be used for:

[0051] According to the change of the open-circuit voltage corresponding to the ion-selective electrode in solutions of multiple preset concentrations, a plurality of second corresponding relationships between the open-circuit voltage and time are correspondingly obtained;

[0052] Perform fitting on the plurality of second corresponding relationships to respectively obtain a plurality of second fitting curve functions;

[0053] Determine the values of a plurality of elastic coefficients respectively according to the plurality of second fitting curve functions; and

[0054] The values ​​of the multiple elastic coefficients and the multiple preset concentrations corresponding thereto are fitted to determine the ion concentration determination function.

[0055] In fact, in addition to ion concentration, there are many factors that affect the electrode response signal. For example, the swelling of the electrode material, the charge transfer process, the electrode material composition, the electrode surface ion adsorption capacity, the ion diffusion rate, etc. in the ion concentration determination will affect the final response signal of the electrode. Therefore, it is usually necessary to use a standard solution for calibration before each measurement to eliminate the influence of these factors. In order to eliminate or minimize the influence of other factors, the application also solidifies the influence ratio of factors affecting the electrode response signal other than ion concentration through parameter optimization during the electrode preparation process, thereby forming a strong correspondence between ion concentration and electrode response signal.

[0056] In some embodiments, the ion selective membrane covering the surface of the ion selective electrode mainly includes ion carriers, plasticizers, surfactants, membrane skeleton materials and other components. To achieve the measurement of ion concentration during polarization, the membrane skeleton material can be optimized, and a polymer material with a low water swelling rate can be used as the skeleton, such as polystyrene, polypropylene, polyamide, polyurethane and a mixture of such polymer materials. In addition, the mass percentage of the surfactant relative to the ion selective membrane can also be reduced (the conventional concentration does not exceed 4%, for example, not more than 1.5%).

[0057] In a specific embodiment, when the ion selective electrode is a calcium ion electrode, the calcium ion selective membrane covered on the calcium ion electrode may contain 1.5% by mass of ion carriers, the membrane skeleton material may be a mixture of polypropylene and polyurethane, the mass ratio of the two may be 2:1, and the amount of surfactant added may be 1%. Experiments show that the calcium ion selective permeable membrane has a low water swelling rate while having calcium ion selective permeability.

[0058] In some embodiments, the membrane liquid of the ion selective membrane is applied to the surface of the ion selective electrode by a controllable deposition method such as spin coating or scraping, avoiding the use of highly discrete methods such as drip coating. The membrane thickness can be effectively controlled by precise coating, and the uniformity of the thickness of the membrane can be ensured. The membrane liquid may also become thicker locally due to inconsistent surface evaporation rates during the volatilization process. Vacuum drying, nitrogen drying and other technical means can be used to control the ambient gas composition during the membrane volatilization process, reduce the condensation of water vapor on the membrane surface, and accelerate the volatilization of organic solvents.

[0059] In a specific embodiment, when the ion-selective electrode is a calcium ion electrode, a nitrogen-filling spin-coating process can be adopted. 10 μL of membrane solution is dropped on the surface of the electrode, and spin-coated at a speed of 1000 rpm for 1 minute in a dry nitrogen environment. After the spin-coating is completed, it is dried in a vacuum oven at 60 °C for 1 hour to fully volatilize the solvent in the membrane solution.

[0060] In some embodiments, the potential after the ion electrode operates stably is related to the ion concentration in the solution. According to the Nernst equation, the electrodes on both sides of the ion-selective membrane in the electrolyte form a battery, and the electromotive force of the battery is equal to the initial electromotive force of the battery plus the relationship of the electrolyte concentration. The initial polarization process is caused by the imbalance of the charge transfer reaction on the surface of the ion-selective electrode, and this deviation is usually related to the charge accumulation on the electrode surface. Therefore, before the initial measurement, the electrode needs to be reversely powered for 2 - 3 seconds to eliminate the original initial charge accumulation. After eliminating the initial charge accumulation, samples of the ion-selective membranes prepared in the same batch can be taken for pre-calibration tests to obtain the charge accumulation rate of this batch of membranes under different ion concentration conditions, and then a standard curve can be determined for subsequent actual measurements.

[0061] According to the solution of the present application, by optimizing the preparation parameters of the ion-selective membrane, the consistency of the membrane polarization process is improved. The ion concentration determination function determined by using the influence of the ion concentration among the change parameters during the electrode potential polarization process enables the detection of the concentration of the ions to be measured in the solution before the potential is stable, greatly improving the sensor response time and achieving the purpose of rapid ion detection.

[0062] The embodiments of the present application have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. At the same time, changes or deformations made by those skilled in the art based on the idea of the present application, within the specific implementation manner and application scope of the present application, all fall within the scope of protection of the present application. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A method for detecting ion concentration using an electrochemical sensor, characterized in that: include: Determining an ion concentration determination function corresponding to the ion selective electrode of the electrochemical sensor, wherein the ion concentration determination function includes a relationship between an elastic coefficient and an ion concentration; According to the change of the open circuit voltage of the ion selective electrode in the solution to be tested within a preset time, a first corresponding relationship between the open circuit voltage and time is obtained, Fitting the first corresponding relationship to determine a first fitting curve function; determining a value of the elastic coefficient according to the first fitting curve function; and The ion concentration of the solution to be tested is calculated according to the ion concentration determination function and the value of the elastic coefficient.

2. The method according to claim 1, characterized in that The step of determining the ion concentration corresponding to the ion selective electrode of the electrochemical sensor comprises: According to the corresponding open circuit voltage changes of the ion selective electrode in the solutions of the plurality of preset concentrations, a plurality of second corresponding relationships between the open circuit voltage and time are correspondingly obtained; Fitting the multiple second corresponding relationships to obtain multiple second fitting curve functions respectively; Determining values ​​of a plurality of elastic coefficients respectively according to the plurality of second fitting curve functions; and The values ​​of the multiple elastic coefficients and the multiple preset concentrations corresponding thereto are fitted to determine the ion concentration determination function.

3. The method according to claim 2, characterized in that The first fitting curve function and any one of the plurality of second fitting curve functions is a logarithmic function Y=alnX+b, wherein Y represents open circuit voltage, X represents time, a represents the elastic coefficient, b is the intercept coefficient, and the ion concentration determination function is an exponential function.

4. An electrochemical sensor, characterized in that include: A processing device, configured to execute the method according to any one of claims 1 to 3.

5. The electrochemical sensor according to claim 4, characterized in that Also includes: Ion selective electrodes; as well as An ion-selective membrane is formed on the surface of the ion-selective electrode.

6. The electrochemical sensor according to claim 5, characterized in that The ion selective membrane comprises a membrane skeleton material and a surfactant, wherein the membrane skeleton material comprises a polymer material with a low swelling rate when exposed to water, and the mass percentage of the surfactant relative to the ion selective membrane does not exceed 4%.

7. The electrochemical sensor according to claim 6, characterized in that The ion selective electrode is a calcium ion selective electrode, the ion selective membrane also includes 1.5% by mass of ion carriers, the membrane skeleton material includes a mixture of polypropylene and polyurethane in a mass ratio of 2:1, and the mass percentage of the surfactant relative to the ion selective membrane is 1%.

8. The electrochemical sensor according to claim 5, characterized in that The ion selective membrane is formed on the surface of the ion selective electrode by: The membrane liquid is applied to the surface of the ion selective electrode by a controlled deposition method and then dried in a vacuum or nitrogen-filled environment.

9. The electrochemical sensor according to claim 5, characterized in that The ion selective membrane is formed on the surface of the ion selective electrode by: Add 10 μL of membrane solution on the surface of the ion selective electrode; Spin coating at 1000 rpm for 1 minute in a dry nitrogen environment; and The film was dried under vacuum at 60 degrees Celsius for 1 hour to evaporate the solvent in the film solution.

10. A device for detecting ion concentration using an electrochemical sensor, characterized in that: include: A first determination module, used to determine an ion concentration determination function corresponding to the ion selective electrode of the electrochemical sensor, wherein the ion concentration determination function includes a relationship between an elastic coefficient and an ion concentration; an acquisition module, for acquiring a first corresponding relationship between the open circuit voltage and time according to a change in the corresponding open circuit voltage of the ion selective electrode in a solution to be tested within a preset time, A second determination module, used for fitting the first corresponding relationship to determine a first fitting curve function; a third determining module, configured to determine a value of the elastic coefficient according to the first fitting curve function; and A calculation module is used to calculate the ion concentration of the solution to be tested according to the ion concentration determination function and the value of the elastic coefficient.

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