Electrochemical sensor, and method and apparatus for measuring ion concentration
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2026-08-13
Smart Images
Figure CN2025108098_13082026_PF_FP_ABST
Abstract
Description
Electrochemical sensors and methods and devices for detecting ion concentration Technical Field
[0001] This application relates to the field of electrochemical sensor technology, and more particularly to an electrochemical sensor and a method and apparatus for detecting ion concentration. Background Technology
[0002] Sodium, potassium, calcium, and other metal ions in water are crucial indicators in water quality testing. The concentration of these ions directly affects water's electrolyte balance, hardness, conductivity, and other properties, significantly impacting numerous industries such as food processing, exercise physiology, household life, and agriculture. Rapid on-site detection of ions in water allows for timely responses to changes in water quality, supporting environmental management and decision-making, and addressing emergencies. In the water treatment industry, rapid on-site detection can create a feedback loop, improving water treatment accuracy and enhancing the real-time nature and visibility of data.
[0003] Currently, the main methods for rapid on-site ion detection include surface plasmon resonance, fluorescent probes, and electrochemical techniques, with electrochemical technology being the most widely used. Electrochemical measurements primarily rely on ion-selective electrodes. The sensitive membrane on an ion-selective electrode selectively allows the passage of specific ions. When an ion passes through the membrane, a potential difference is generated at the membrane-solution interface. This potential difference has a logarithmic relationship with the ion concentration in the solution. By measuring the potential difference between the two electrodes, quantitative analysis of ion concentration can be performed. However, ion-selective electrodes undergo a polarization process at the initial stage of measurement, which typically lasts from tens of minutes to several hours. Concentration measurement can only begin after the polarization is complete and the electrode reaches a stable potential state. Therefore, the immediacy of rapid on-site ion electrochemical detection is affected.
[0004] The primary cause of polarization is the deviation of the electrode potential from its theoretical value due to the imbalance of charge transfer reactions on the surface of the ion-selective electrode. This deviation is usually related to charge accumulation on the electrode surface, leading to a discrepancy between the actual measured potential and the potential predicted by the Nernst equation. In practical measurements, potential polarization is unavoidable, making it difficult to effectively reduce the time required for on-site detection and thus hindering the acquisition of ion concentration data in a short period. Summary of the Invention
[0005] Based on this, this application provides an electrochemical sensor and a scheme for detecting ion concentration implemented by the electrochemical sensor to address the problems existing in the prior art, which can quickly acquire ion concentration data without waiting for polarization to complete.
[0006] According to a first aspect of this application, a method for detecting ion concentration using an electrochemical sensor is provided, characterized in that it includes:
[0007] A function for determining the ion concentration corresponding to the ion-selective electrode of the electrochemical sensor is determined, wherein the ion concentration determination function includes the relationship between the elastic coefficient and the ion concentration;
[0008] Based on the change in the open-circuit voltage of the ion-selective electrode in the test solution within a preset time, a first correspondence between the open-circuit voltage and time is obtained;
[0009] Fit the first correspondence to determine the first fitted curve function;
[0010] The value of the elastic coefficient is determined based on the first fitted curve function; and
[0011] The ion concentration of the test solution is calculated based on the ion concentration determination function and the value of the elastic coefficient.
[0012] According to a second aspect of this application, an electrochemical sensor is provided, characterized in that it comprises:
[0013] A processing device for performing the method described in the first aspect.
[0014] According to a third aspect of this application, an apparatus for detecting ion concentration using an electrochemical sensor is provided, characterized in that it comprises:
[0015] The first determining module is used to determine the ion concentration determining function corresponding to the ion selective electrode of the electrochemical sensor, wherein the ion concentration determining function includes the relationship between the elastic coefficient and the ion concentration;
[0016] The acquisition module is used to acquire a first correspondence between the open-circuit voltage and time based on the change in the open-circuit voltage of the ion-selective electrode within a preset time in the test solution.
[0017] The second determining module is used to fit the first correspondence relationship and determine the first fitting curve function;
[0018] The third determining module is used to determine the value of the elastic coefficient based on the first fitted curve function; and
[0019] The calculation module is used to calculate the ion concentration of the test solution based on the ion concentration determination function and the value of the elastic coefficient.
[0020] According to the electrochemical sensor and the method and apparatus for detecting ion concentration provided in this application, an ion-selective electrode is tested using a standard solution with a preset ion concentration to obtain an ion concentration determination function. During actual solution ion concentration measurement, the ion concentration of the test solution is determined using this function, eliminating the need to wait for polarization to complete and thus enabling rapid acquisition of ion concentration data. The solution presented in this application is applicable to all potentiometric electrochemical sensors that measure ion concentration using ion-selective membranes, and is universally applicable in the field of point-of-care ion detection. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings, without exceeding the scope of protection claimed by this application.
[0022] Figure 1 is a schematic diagram of the fitting curve of the relationship between the fitted open-circuit voltage and time according to an embodiment of this application.
[0023] Figure 2 is a schematic diagram of the ion concentration determination function curve of the fitting elasticity coefficient and ion concentration according to an embodiment of this application.
[0024] Figure 3 is a flowchart illustrating 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 an apparatus for detecting ion concentration using an electrochemical sensor according to an embodiment of this application. Detailed Implementation
[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0027] Throughout the specification and claims, terms may have subtle meanings implied or implied in the context, rather than explicitly stated meanings. Similarly, the phrases “in one embodiment” or “in some embodiments” as used herein do not necessarily refer to the same embodiment, and the phrases “in another embodiment” or “in other embodiments” as used herein do not necessarily refer to different embodiments. The phrases “in one implementation” or “in some implementations” as used herein do not necessarily refer to the same implementation, and the phrases “in another implementation” or “in other implementations” as used herein do not necessarily refer to different implementations. For example, the claimed subject matter includes all or part of a combination of exemplary embodiments or implementations.
[0028] Generally, terms can be understood at least in part from their use in context. For example, terms used herein, such as “and,” “or,” and “and / or,” can include a variety of meanings, which can depend at least in part on the context in which they are used. Typically, “or,” when used in an associative list, such as A, B, or C, means A, B, and C, here used for inclusion, and A, B, or C, here used only for exclusion. Furthermore, the terms “one or more” or “at least one,” as used herein, depend at least in part on the context and can be used to describe any feature, structure, or characteristic in a singular sense, or can be used to describe a combination of features, structures, and characteristics in a plural sense. Similarly, terms such as “a,” “an,” or “described,” depend at least in part on the context and can be understood to convey either singular or plural usage. Moreover, also depending at least in part on the context, the terms “based on” or “determined by” can be understood not necessarily to indicate a set of exclusive factors; rather, they may allow for the presence of other factors that are not necessarily explicitly described.
[0029] In general, the inventive concept of this application is as follows: An ion-selective electrode is tested using standard solutions with various preset ion concentrations. The open-circuit voltage and its relationship with time are recorded to obtain a first ion concentration determination function. The elastic coefficient is then determined using this first ion concentration determination function. Next, based on the relationship between the elastic coefficient and the ion concentration, an ion concentration determination function is fitted. During actual solution ion concentration measurement, the open-circuit voltage and its relationship with time are recorded to obtain a second ion concentration determination function. The elastic coefficient obtained during the actual measurement is then determined using this second ion concentration determination function. Finally, the ion concentration of the solution to be tested is determined based on the ion concentration determination function and the elastic coefficient obtained during the actual measurement.
[0030] In some embodiments, the electrochemical sensor employs a two-electrode configuration, including an ion-selective electrode and a reference electrode, with an ion-selective film 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 will understand that other two-electrode configurations may also be used, and this application does not impose any limitations on these configurations.
[0031] In some embodiments, ion-selective electrodes prepared from the same batch of membrane solution are sampled and tested to determine polarization standard curves at various ion concentrations. For example, calcium ion electrodes are tested using calcium ion standard solutions of concentrations of 1 μM, 10 μM, 100 μM, and 1 mM, respectively. The open-circuit voltage change curves within a preset time (e.g., 50 seconds) after the calcium ion electrode contacts the solution are recorded using an electrochemical workstation. After each test, the electrode surface can be rinsed with deionized water and air-dried at room temperature. Those skilled in the art will understand that other concentrations, types, and quantities of standard solutions can also be used, and the preset contact time of the ion-selective electrode with the solution can be any suitable length, all of which fall within the scope of this application.
[0032] Figure 1 is a schematic diagram of the fitted curves of the open-circuit voltage and time relationship according to an embodiment of this application. As shown in Figure 1, four open-circuit voltage and time relationship curves are included. These curves are fitted to obtain the fitted curve and the fitted curve function. In a specific embodiment, the fitted curve function can be in the form of a logarithmic function Y = a1nX + b, where Y represents the open-circuit voltage, X represents time, a is the elasticity coefficient (or elasticity value) of the fitted curve function, and b is the intercept coefficient. As shown in Figure 1, the values of the elasticity coefficient a for the four open-circuit voltage and time relationship curves are -4.85, -8.67, -14.53, and -18.36, respectively.
[0033] Figure 2 is a schematic diagram of the ion concentration determination function curve showing the relationship between the fitted elasticity coefficients and ion concentrations according to an embodiment of this application. In some embodiments, after determining the ion concentrations of multiple standard solutions and the corresponding values of multiple elasticity coefficients, the ion concentrations of the multiple standard solutions and the corresponding values of multiple elasticity coefficients are fitted to determine the ion concentration determination function. In one specific embodiment, as shown in Figure 2, the function after fitting the ion concentrations of multiple standard solutions and the corresponding values of multiple elasticity coefficients is an exponential function.
[0034] In some implementations, after determining the ion concentration determination function corresponding to the ion-selective electrode, when actually measuring a solution of unknown concentration using the ion-selective electrode, the relationship between open-circuit voltage and time can be obtained based on the change in open-circuit voltage of the ion-selective electrode within a preset time in the solution to be tested. Then, the relationship is fitted to determine the fitting curve function; the value of the elastic coefficient is determined based on the fitting curve function; finally, the ion concentration of the solution to be tested is calculated based on the ion concentration determination function and the value of the elastic coefficient.
[0035] Based on the above description, according to one aspect of this application, a method for detecting ion concentration using an electrochemical sensor is provided. As shown in Figure 3, the method includes the following steps.
[0036] Step S301: 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;
[0037] Step S302: Based on the change in open-circuit voltage of the ion-selective electrode within a preset time in the test solution, obtain the first correspondence between the open-circuit voltage and time.
[0038] Step S303: Fit the first correspondence to determine the first fitting curve function;
[0039] Step S304: Determine the value of the elastic coefficient based on the first fitted curve function; and
[0040] Step S305: Calculate the ion concentration of the solution to be tested based on the ion concentration determination function and the value of the elastic coefficient.
[0041] In some implementations, in order to quickly measure ion concentration, it is necessary to determine the ion concentration determination function that reflects the relationship between the elastic coefficient and the ion concentration, as well as 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, based on the ion concentration determination function and the value of the elastic coefficient, the ion concentration of the solution to be tested is calculated.
[0042] It is understood that steps S301 and S302-304 can be performed sequentially or simultaneously, and this application does not impose any restrictions on this.
[0043] In some optional embodiments, step S301, which determines the ion concentration determination function, may include the following steps:
[0044] Based on the changes in open-circuit voltage of the ion-selective electrode in solutions of multiple preset concentrations, multiple second correspondences between open-circuit voltage and time are obtained accordingly.
[0045] The plurality of second correspondences are fitted to obtain a plurality of second fitted curve functions;
[0046] The values of multiple elastic coefficients are determined based on the multiple second fitting curve functions; and
[0047] The ion concentration determination function is determined by fitting the values of the plurality of elastic coefficients and their corresponding plurality of preset concentrations.
[0048] In some embodiments, the change in open-circuit voltage of the electrode can be measured in solutions of multiple known concentrations to determine multiple correspondences between open-circuit voltage and time. The multiple correspondences are fitted to obtain multiple fitted curve functions and values of multiple elastic coefficients. The values of multiple elastic coefficients are fitted to multiple preset concentrations to determine the ion concentration determination function.
[0049] According to another aspect of this application, an apparatus for detecting ion concentration using an electrochemical sensor is provided. As shown in FIG4, the apparatus includes: a first determining module 401, an acquiring module 402, a second determining module 403, a third determining module 404, and a calculation module 405. The first determining module 401 is 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 the relationship between an elastic coefficient and the ion concentration; the acquiring module 402 is used to acquire a first correspondence between the open-circuit voltage and time based on the change in the open-circuit voltage of the ion-selective electrode in the test solution within a preset time; the second determining module 403 is used to fit the first correspondence to determine a first fitting curve function; the third determining module 404 is used to determine the value of the elastic coefficient based on the first fitting curve function; and the calculation module 405 is used to calculate the ion concentration of the test solution based on the ion concentration determination function and the value of the elastic coefficient.
[0050] In some alternative embodiments, the first determining module 401 may be used to:
[0051] Based on the changes in open-circuit voltage of the ion-selective electrode in solutions of multiple preset concentrations, multiple second correspondences between open-circuit voltage and time are obtained accordingly.
[0052] The plurality of second correspondences are fitted to obtain a plurality of second fitted curve functions;
[0053] The values of multiple elastic coefficients are determined based on the multiple second fitting curve functions; and
[0054] The ion concentration determination function is determined by fitting the values of the plurality of elastic coefficients and their corresponding plurality of preset concentrations.
[0055] In fact, besides ion concentration, many other factors affect the electrode response signal. For example, the swelling of the electrode material, the charge transfer process, the composition of the electrode material, the ion adsorption capacity of the electrode surface, and the ion diffusion rate all affect the final response signal of the electrode. Therefore, it is usually necessary to calibrate with a standard solution before each measurement to eliminate the influence of these factors. To eliminate or minimize the influence of other factors, this application also optimizes the parameters in the electrode preparation process to solidify the influence ratio of factors other than ion concentration that affect the electrode response signal, thereby forming a strong correlation between ion concentration and electrode response signal.
[0056] In some embodiments, the ion-selective membrane covering the surface of the ion-selective electrode mainly comprises components such as ion carriers, plasticizers, surfactants, and membrane framework materials. To achieve ion concentration measurement during the polarization process, the membrane framework material can be optimized, using polymer materials with low water swelling rates as the framework, such as polystyrene, polypropylene, polyamide, polyurethane, and mixtures of such polymer materials. Additionally, the mass percentage of the surfactant relative to the ion-selective membrane can be reduced (typically not exceeding 4%, for example, not exceeding 1.5%).
[0057] In one specific embodiment, when the ion-selective electrode is a calcium ion electrode, the calcium ion-selective membrane covering the calcium ion electrode may contain 1.5% by mass of ion carrier, and the membrane skeleton material may be a mixture of polypropylene and polyurethane in a mass ratio of 2:1; the amount of surfactant added may be 1%. Experiments show that this calcium ion-selective permeable membrane has a low water swelling rate while possessing calcium ion selective permeability.
[0058] In some embodiments, the membrane solution of the ion-selective membrane is coated onto the surface of the ion-selective electrode using controlled deposition methods such as spin coating or blade coating, avoiding highly discrete methods such as drop coating. Precise coating effectively controls the membrane thickness and ensures uniformity throughout the membrane. During the evaporation process, inconsistent surface evaporation rates may cause localized thickening. Vacuum drying, nitrogen-purging drying, and other techniques can be used to control the composition of ambient gases during membrane evaporation, reduce water vapor condensation on the membrane surface, and accelerate the evaporation of organic solvents.
[0059] In one specific embodiment, when the ion-selective electrode is a calcium ion electrode, a nitrogen-filled spin coating process can be used. 10 μL of film solution is dropped onto the surface of the electrode, and spin coating is performed at 1000 rpm for 1 minute in a dry nitrogen environment. After spin coating, the film solution is dried in a vacuum oven at 60 degrees Celsius for 1 hour to allow the solvent in the film solution to fully evaporate.
[0060] In some embodiments, the potential of the ion-selective electrode after stable operation 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 constitute a battery, and the electromotive force of the battery is equal to the initial electromotive force plus the electrolyte concentration. The initial polarization process is caused by the imbalance of charge transfer reaction on the surface of the ion-selective electrode. This deviation is usually related to the accumulation of charge on the electrode surface. Therefore, before the initial measurement, the electrode needs to be reverse-energized for 2-3 seconds to eliminate the original initial charge accumulation. After eliminating the initial charge accumulation, samples of ion-selective membranes prepared in the same batch can be sampled for pre-calibration testing to obtain the charge accumulation rate of the batch of membranes under different ion concentration conditions, thereby determining the standard curve for subsequent actual measurements.
[0061] According to the scheme of this 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 is determined by utilizing the influence of ion concentration in the changing parameters of the electrode potential polarization process. This enables the detection of the concentration of the analyte ion in the solution before the potential stabilizes, significantly improving the sensor response time and achieving the goal of rapid ion detection.
[0062] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. Furthermore, any changes or modifications made by those skilled in the art based on the ideas of this application, and on the specific implementation methods and application scope of this application, are all within the scope of protection of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A method for detecting ion concentration using an electrochemical sensor, characterized in that, include: A function for determining the ion concentration corresponding to the ion-selective electrode of the electrochemical sensor is determined, wherein the ion concentration determination function includes the relationship between the elastic coefficient and the ion concentration; Based on the change in open-circuit voltage of the ion-selective electrode within a preset time in the test solution, a first correspondence between the open-circuit voltage and time is obtained. Fit the first correspondence to determine the first fitted curve function; The value of the elastic coefficient is determined based on the first fitted curve function; and The ion concentration of the test solution is calculated based on the ion concentration determination function and the value of the elastic coefficient.
2. The method as described in claim 1, characterized in that, The function for determining the ion concentration corresponding to the ion-selective electrode of the electrochemical sensor includes: Based on the changes in open-circuit voltage of the ion-selective electrode in solutions of multiple preset concentrations, multiple second correspondences between open-circuit voltage and time are obtained accordingly. The plurality of second correspondences are fitted to obtain a plurality of second fitted curve functions; The values of multiple elastic coefficients are determined based on the multiple second fitting curve functions; and The ion concentration determination function is determined by fitting the values of the plurality of elastic coefficients and their corresponding plurality of preset concentrations.
3. The method as described in 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, where Y represents the 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 for performing the method as described in any one of claims 1 to 3.
5. The electrochemical sensor as described in claim 4, characterized in that, Also includes: Ion-selective electrode; as well as An ion-selective membrane is formed on the surface of the ion-selective electrode.
6. The electrochemical sensor as described in claim 5, characterized in that, The ion-selective membrane comprises a membrane framework material and a surfactant. The membrane framework material comprises a polymer material with a low water swelling rate, and the surfactant accounts for no more than 4% of the mass of the ion-selective membrane.
7. The electrochemical sensor as described in claim 6, characterized in that, The ion-selective electrode is a calcium ion-selective electrode, the ion-selective membrane further includes 1.5% by mass of an ion carrier, the membrane skeleton material includes a mixture of polypropylene and polyurethane in a mass ratio of 2:1, and the surfactant is 1% by mass relative to the ion-selective membrane.
8. The electrochemical sensor as described in claim 5, characterized in that, The ion-selective membrane is formed on the surface of the ion-selective electrode in the following manner: The membrane solution is applied to the surface of the ion-selective electrode by controlled deposition and then dried in a vacuum or nitrogen-filled environment.
9. The electrochemical sensor as described in claim 5, characterized in that, The ion-selective membrane is formed on the surface of the ion-selective electrode in the following manner: 10 μL of film solution was dropped onto the surface of the ion-selective electrode; Spin-coating at 1000 rpm for 1 minute in a dry nitrogen atmosphere; and Dry in a vacuum at 60 degrees Celsius for 1 hour to evaporate the solvent in the membrane solution.
10. A device for detecting ion concentration using an electrochemical sensor, characterized in that, include: The first determining module is used to determine the ion concentration determining function corresponding to the ion selective electrode of the electrochemical sensor, wherein the ion concentration determining function includes the relationship between the elastic coefficient and the ion concentration; The acquisition module is used to acquire a first correspondence between the open-circuit voltage and time based on the change in the open-circuit voltage of the ion-selective electrode within a preset time in the test solution. The second determining module is used to fit the first correspondence relationship and determine the first fitting curve function; The third determining module is used to determine the value of the elastic coefficient based on the first fitted curve function; and The calculation module is used to calculate the ion concentration of the test solution based on the ion concentration determination function and the value of the elastic coefficient.