A flexible wearable potassium ion detection sensor and preparation method thereof

Abstract

The present invention discloses a flexible wearable potassium ion detection sensor and a preparation method thereof, and relates to the field of flexible sensors. The flexible wearable potassium ion detection sensor comprises an electrode, a liquid film and a substrate, wherein the liquid film covers the surface of the electrode, and the electrode is arranged on the substrate; the electrode comprises a three-electrode system and a two-electrode system; the three-electrode system comprises a working electrode, a reference electrode and a counter electrode; the two-electrode system comprises a working electrode and a reference electrode; the working electrode, the reference electrode and the counter electrode are prepared by a micro-nano processing method or a screen printing method and arranged on the substrate, and the substrate is a flexible planar substrate or a flexible microneedle substrate. The present invention adopts the above-mentioned flexible wearable potassium ion detection sensor and a preparation method thereof, replaces the traditional glass membrane + internal reference solution structure, greatly reduces the volume of the potassium ion selective electrode, realizes the miniaturization of the potassium ion sensor, enhances the practicability, and broadens the scope of application.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible sensors, and in particular to a flexible wearable potassium ion detection sensor and a preparation method thereof. Background Art

[0002] Wearable sensor technology is essential for personalized medicine that understands personal health status through uninterrupted and continuous monitoring. Human sweat contains rich physiological information, and the collection of human sweat is non-invasive, ensuring the user experience. Given the complexity of sweat secretion, multiple simultaneous screening of target biomarkers is critical; this requires complete system integration to ensure the accuracy of measurement. In this work, a multiplexed sensor array was used to analyze raw sweat, measure sweat metabolites (such as glucose and lactate) and electrolytes (such as sodium ions and potassium ions), and skin temperature (calibration of sensor response). By preparing wearable biosensors on plastic substrates and integrating wireless transmission silicon integrated sensor circuits on flexible circuit boards, this work bridges the barriers between signal conduction (amplification and filtering) and processing. The wearable system can be used to test the sweat of human subjects and evaluate the physiological state of subjects engaged in long-term indoor activities in real time.

[0003] Potassium is an essential macronutrient in human nutrition and the main cation in animal cells. It is also very important in the balance of body fluids and electrolytes. Potassium plays an important role in maintaining myocardial function, maintaining the nervous system, maintaining cell water content and body fluid acid-base balance. Lack of potassium ions in the body may lead to arrhythmia, rapid heartbeat and even nervous system disorders. Potassium ions are mainly excreted through the kidneys, but they are contained in blood and other body fluids because 98% of potassium exists inside cells. When the human body sweats a lot, potassium ions will be lost with sweat, so detecting the concentration of potassium ions in sweat is extremely important for maintaining the health of the body during exercise.

[0004] The ion-selective electrodes prepared by cell assembly on pH glass membranes show excellent electromotive force response, and there are no significant defects in selectivity, stability, and lifespan. However, compared with those solvent-polymer membranes, some disadvantages of glass membranes become obvious: for example, it is difficult to assemble them into tiny electrode assemblies to measure cell flow, and the large resistance of glass membranes is also an obstacle in some cases. In addition, glass membranes are more easily affected by certain human interferences, such as components from biological samples (protein deposition), and require special regular rinsing treatments. For some application scenarios that require entering the human body for measurement, safety is also another serious problem (such as catheter electrodes). Therefore, the present invention attempts to make innovative potassium ion selective electrodes on flexible substrates to produce wearable potassium ion sensors, thereby realizing real-time and on-site detection of potassium ion concentrations in human sweat, and providing accurate and reliable analytical data for motion analysis and health monitoring. Summary of the invention

[0005] The purpose of the present invention is to provide a flexible wearable potassium ion detection sensor and a preparation method thereof, which replaces the traditional glass membrane + internal reference solution structure, greatly reduces the volume of the potassium ion selective electrode, realizes the miniaturization of the potassium ion sensor, enhances the practicability, and broadens the scope of application.

[0006] To achieve the above-mentioned purpose, the present invention provides a flexible wearable potassium ion detection sensor, comprising an electrode, a liquid film and a substrate, the liquid film covering the surface of the electrode, and the electrode being arranged on the substrate; the electrode comprises a three-electrode system and a two-electrode system; the three-electrode system comprises a working electrode, a reference electrode and a counter electrode; the two-electrode system comprises a working electrode and a reference electrode (the reference electrode also has the function of a counter electrode); the working electrode, the reference electrode and the counter electrode are prepared by a micro-nano processing method or a screen printing method and arranged on a substrate, and the substrate is a flexible planar substrate or a flexible microneedle substrate; the flexible planar substrate comprises any one of polyethylene terephthalate, polyethylene naphthalate, polyimide, polydimethylsiloxane, adhesive tape, paper, Band-Aid or cotton cloth, and the flexible microneedle substrate comprises any one of biocompatible materials, biodegradable materials or plastics, including chitosan, polylactic acid, thermoplastic polyurethane elastomer rubber, etc.

[0007] Furthermore, the steps of preparing the working electrode and / or the counter electrode by the micro-nano processing method are: evaporating or sputtering to obtain a nanolayer of gold or platinum, and then electroplating it to produce a Prussian blue layer to obtain a platinum / Prussian blue electrode or a gold / Prussian blue electrode; the steps of preparing the reference electrode by the micro-nano processing method are: sputtering or evaporating to produce a silver electrode, and then partially converting the silver into silver chloride through a chemical reaction in a ferric chloride solution to obtain a silver / silver chloride electrode.

[0008] Furthermore, the steps of preparing the working electrode and / or the counter electrode by the screen printing method are: screen printing gold composite slurry, platinum composite slurry, carbon composite slurry, and drying to obtain the working electrode and / or the counter electrode; the steps of preparing the reference electrode by the screen printing method are: screen printing silver / silver chloride composite slurry, and drying to obtain the reference electrode.

[0009] Furthermore, in the three-electrode system, the working electrode, reference electrode and counter electrode are arranged adjacent to each other, and the distance between the working electrode, reference electrode and counter electrode is set to 0.5-3mm; in the two-electrode system, the working electrode and reference electrode are arranged adjacent to each other, and the distance between the working electrode and the reference electrode is set to 0.5-3mm.

[0010] Furthermore, the liquid membrane includes liquid membrane A and liquid membrane B; liquid membrane A covers the surface of the working electrode, and liquid membrane B covers the surface of the reference electrode; the components of liquid membrane A include 2% w / w valinomycin, 0.5% w / w sodium tetraphenylborate, 32.7% w / w PVC polyvinyl chloride and 64.7% w / w dioctyl sebacate, and the components of liquid membrane B include polyvinyl butyral, sodium chloride and methanol.

[0011] Furthermore, the preparation method of the liquid film A is as follows:

[0012] 2% w / w valinomycin, 0.5% w / w sodium tetraphenylborate, 32.7% w / w PVC polyvinyl chloride and 64.7% w / w dioctyl sebacate were stirred evenly, and 350 μL cyclohexanone was added to 100 mg of the mixed solution to obtain a liquid membrane A solution;

[0013] The preparation method of liquid membrane B is as follows: 79.1 mg of polyvinyl butyral, 50 mg of sodium chloride and 1 mL of methanol are mixed evenly to obtain a liquid membrane B solution.

[0014] The present invention also provides a method for preparing the above-mentioned flexible wearable potassium ion detection sensor, comprising the following steps:

[0015] a. Making a flexible planar substrate or a flexible microneedle substrate;

[0016] b. forming an electrode mold on the substrate, adding electrode materials into the corresponding electrode molds respectively, and drying to obtain electrodes;

[0017] c. Take 20 μL of liquid membrane A solution, add it evenly onto the working electrode with a pipette, take 20 μL of liquid membrane B solution, add it evenly onto the reference electrode with a pipette, and then place the electrode in a 4°C refrigerator to dry for 12 hours to obtain a flexible wearable potassium ion detection sensor.

[0018] Furthermore, in the step b, the electrode mold is a mold for making an electrode shape. When the substrate is a flexible planar substrate, the overall electrode size of the working electrode, the reference electrode and the counter electrode is 1mm-10mm in diameter and 10-200μm in thickness; when the substrate is a flexible microneedle substrate, the working electrode, the reference electrode and the counter electrode are all rectangles formed by an array of cones, and the size can be (1mm-10mm)×(5mm-2cm), the microneedle height is 300-1500μm, the bottom diameter is 100-500μm, the spacing range is 100-1000μm, and the electrode thickness is 50-300nm.

[0019] The advantages and positive effects of the flexible wearable potassium ion detection sensor and the preparation method thereof described in the present invention are:

[0020] 1. In the present invention, the working electrode is a gold or platinum electrode, the reference electrode is silver / silver chloride, and the coating is a silver / silver chloride slurry with a mass fraction of 50:50, which can provide a stable potential in a sulfur-free environment and is suitable for the research environment of the present invention.

[0021] 2. The present invention replaces the traditional glass membrane + internal reference solution structure, greatly reduces the volume of the potassium ion selective electrode, realizes the miniaturization of the potassium ion sensor, enhances practicality, and broadens the scope of application.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the three-electrode system structure in the present invention;

[0024] Figure 2 Schematic diagram of the structure of the dual-electrode system (flexible microneedle substrate) in the present invention;

[0025] Figure 3 Schematic diagram of the structure of the dual-electrode system (flexible planar substrate) in the present invention;

[0026] Figure 4 The present invention is a flow chart for preparing a dual-electrode system sensor;

[0027] Figure 5 The OPCT test results of the potassium ion selective electrode in the present invention;

[0028] Figure 6 This is the standard working curve of the potassium ion selective electrode in the present invention.

[0029] Reference numerals

[0030] 1. Working electrode; 2. Reference electrode; 3. Counter electrode; 4. Substrate. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0032] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0033] Example 1 Electrode structure

[0034] A flexible wearable potassium ion detection sensor includes an electrode, a liquid film and a substrate 4. The liquid film covers the surface of the electrode, and the electrode is arranged on the substrate 4. The electrode includes a three-electrode system and a two-electrode system. Figure 1 As shown, the three-electrode system includes a working electrode 1, a reference electrode 2 and a counter electrode 3. Figure 2 As shown, the two-electrode system includes a working electrode 1 and a reference electrode 2. The substrate 4 is a flexible planar substrate or a flexible microneedle substrate.

[0035] The working electrode, the reference electrode and the counter electrode are prepared by micro-nano processing or screen printing and arranged on a substrate, which is a flexible planar substrate or a flexible microneedle substrate. The flexible planar substrate includes any one of polyethylene terephthalate, polyethylene naphthalate, polyimide, polydimethylsiloxane, adhesive tape, paper, band-aid or cotton cloth, and the flexible microneedle substrate includes any one of biocompatible materials, biodegradable materials or plastics, including chitosan, polylactic acid, thermoplastic polyurethane elastomer rubber, etc.

[0036] In the three-electrode system, the working electrode 1, the reference electrode 2 and the counter electrode 3 are arranged adjacent to each other, and the distance between the working electrode 1, the reference electrode 2 and the counter electrode 3 is set to 0.5-3 mm. Figure 3 As shown, in the dual-electrode system, the working electrode 1 and the reference electrode 2 are arranged adjacent to each other, and the distance between the working electrode 1 and the reference electrode 2 is set to 0.5-3 mm.

[0037] like Figure 2As shown, the working electrode 1 and the reference electrode 2 on the flexible microneedle substrate are rectangles formed by a plurality of cone arrays with dimensions of (1mm-10mm)×(5mm-2cm), a microneedle height of 300-1500μm, a bottom diameter of 100-500μm, a spacing range of 100-1000μm, an electrode thickness of 50-300nm, and the working electrode 1 and the reference electrode 2 are arranged adjacent to each other, and the distance between the working electrode 1 and the reference electrode 2 is set to 0.5-3mm.

[0038] The steps of preparing the working electrode 1 and / or the counter electrode 3 by the micro-nano processing method are: evaporating or sputtering to obtain a nano-layer of gold or platinum, and then electroplating a Prussian blue layer thereon to obtain a platinum / Prussian blue electrode or a gold / Prussian blue electrode. The steps of preparing the reference electrode 2 by the micro-nano processing method are: sputtering or evaporating to produce a silver electrode, and then partially converting the silver into silver chloride through a chemical reaction in a ferric chloride solution to obtain a silver / silver chloride electrode.

[0039] The steps of preparing the working electrode 1 and / or the counter electrode 3 by the screen printing method are: screen printing gold composite slurry, platinum composite slurry, carbon composite slurry, and drying to obtain the working electrode 1 and / or the counter electrode 3. The steps of preparing the reference electrode 2 by the screen printing method are: screen printing silver / silver chloride composite slurry, and drying to obtain the reference electrode 2.

[0040] The following examples use a dual-electrode system as an example for subsequent experiments.

[0041] Example 2 Preparation of liquid membrane

[0042] The reagents used for preparing the liquid membrane and their uses are shown in Table 1.

[0043] Table 1 Reagents used and their uses

[0044] Reagent name use Polyvinyl chloride (PVC) Polymer framework Sodium tetraphenylboron Anionic shielding agent Dioctyl Sebacate(DOS) Organic solvents, plasticizers Valinomycin Potassium ionophore Sodium chloride Prepare artificial sweat and make reference electrode Sodium lactate Preparation of artificial sweat Cyclohexanone Transferring the organic solvent-polymer mixture to the electrode Polyvinyl butyral (PVB) Polymer framework Methanol Organic solvents

[0045] The liquid membrane includes liquid membrane A and liquid membrane B, wherein liquid membrane A covers the surface of the working electrode 1, and liquid membrane B covers the surface of the reference electrode 2. The components of liquid membrane A include 2% w / w valinomycin, 0.5% w / w sodium tetraphenylborate, 32.7% w / w PVC polyvinyl chloride and 64.7% w / w dioctyl sebacate, and the components of liquid membrane B include polyvinyl butyral, sodium chloride and methanol.

[0046] The preparation method of liquid membrane A is as follows: 2% w / w valinomycin, 0.5% w / w sodium tetraphenylborate, 32.7% w / w PVC polyvinyl chloride and 64.7% w / w dioctyl sebacate are uniformly stirred, and 350 μL cyclohexanone is added to 100 mg of the mixed solution to obtain a liquid membrane A solution;

[0047] The preparation method of liquid membrane B is as follows: 79.1 mg of polyvinyl butyral, 50 mg of sodium chloride and 1 mL of methanol are mixed evenly to obtain a liquid membrane B solution.

[0048] Example 3 Preparation of flexible wearable potassium ion detection sensor (two-electrode system)

[0049] A method for preparing a flexible wearable potassium ion detection sensor (two-electrode system) comprises the following steps (such as Figure 4 shown):

[0050] a. Making a flexible planar substrate or a flexible microneedle substrate;

[0051] b. forming an electrode mold on a substrate 4, adding materials of a working electrode 1 and a reference electrode 2 into the corresponding electrode molds respectively, and drying to obtain the working electrode 1 and the reference electrode 2;

[0052] c. Take 20 μL of liquid membrane A solution, add it onto the working electrode 1 with a pipette to cover it evenly, take 20 μL of liquid membrane B solution, add it onto the reference electrode 2 with a pipette to cover it evenly, and then place the electrodes in a 4°C refrigerator to dry for 12 hours to obtain a flexible wearable potassium ion detection sensor.

[0053] In step b, the electrode mold is a mold for making an electrode shape. When the substrate 4 is a flexible planar substrate, the overall electrode size of the working electrode, the reference electrode and the counter electrode is 1mm-10mm in diameter and 10-200μm in thickness; when the substrate is a flexible microneedle substrate, the working electrode, the reference electrode and the counter electrode are all rectangles formed by an array of cones, and the size can be (1mm-10mm)×(5mm-2cm), the microneedle height is 300-1500μm, the bottom diameter is 100-500μm, the spacing range is 100-1000μm, and the electrode thickness is 50-300nm.

[0054] In step b, the dual-electrode system is manufactured by micro-nano processing or screen printing.

[0055] The micro-nano processing method of the dual-electrode system is as follows:

[0056] (1) Working electrode 1: A nano-layer of gold or platinum is obtained by evaporation or sputtering using a micro-nano processing method, and then a Prussian blue layer is electroplated on it to obtain a platinum / Prussian blue electrode or a gold / Prussian blue electrode;

[0057] (2) Reference electrode 2: Sputtering or evaporation produces a silver electrode, and then part of the silver reacts in a ferric chloride solution to produce silver chloride, thereby obtaining a silver / silver chloride electrode;

[0058] The screen printing method for the two-electrode system is as follows:

[0059] (1) Working electrode 1: screen printing gold composite slurry, platinum composite slurry, carbon composite slurry;

[0060] (2) Reference electrode 2: screen-printed silver / silver chloride composite paste.

[0061] The processing method of the working electrode 1 and the counter electrode 3 in the three-electrode system refers to the processing method of the working electrode 1 in the two-electrode system, and the processing method of the reference electrode 2 in the three-electrode system refers to the processing method of the reference electrode 2 in the two-electrode system.

[0062] Example 4 Performance Test

[0063] After the sensor is prepared, the electrolyte solution to be added to the solution chamber during measurement needs to be prepared. While ensuring the conductivity of artificial sweat, we hope to restore the real composition of sweat as much as possible. Sodium chloride and sodium lactate are added to ultrapure water to simulate human sweat, with 150mmol / L sodium chloride and 10mmol / L sodium lactate.

[0064] The OCPT measurement method, OCPT, namely Open Circuit Potential vs. Time, measures the change of open circuit voltage with time as the horizontal axis; the open circuit potential (also called equilibrium potential, static potential or corrosion potential) is the potential when no external load is connected and no current flows between the two ends. Connect the working electrode of the electrochemical workstation to the gold or platinum electrode of the sensor, and the counter electrode and reference electrode of the workstation to the silver / silver chloride electrode. With the potential of the reference electrode 2 in the solution as a reference, measure the potential change of the working electrode 1 in the solution, thereby reacting to the change of the membrane potential and obtaining the concentration change of the ion to be measured in the solution.

[0065] In the test, 200 μL of artificial sweat was selected as the basic solution. Figure 5 and sequence numbers 1-4 in Table 2 are 10 μL of 1 mol / L KCl solution added dropwise to the solution each time to gradually increase the potassium ion concentration in the solution; Figure 5 In sequence number 5, 100 μL of 1 mol / L NaCl solution was added to the solution to verify the ion selectivity of the electrode. After the fifth addition, the voltage rose briefly and then fell back to 0.232 V, indicating that the NaCl interference could be well shielded. The specific results are shown in Table 2.

[0066] Table 2 Relationship between total KCl concentration and voltage in solution after adding KCl

[0067] Dropping sequence number Total KCl concentration mmol / L log(K+)mmol / L Voltage V No dripping 0 N / A 0.183 1 47.619 1.678 0.208 2 90.909 1.959 0.219 3 130.435 2.115 0.227 4 166.667 2.221 0.232

[0068] Combination Figure 5 As shown in Table 2, we use the logarithm of potassium ion concentration as the horizontal axis and the open circuit voltage as the vertical axis to plot the following: Figure 6 The standard working curve shown is:

[0069] like Figure 6 As shown, the potassium ion electrode conforms to the Nernst formula, V = k*logA + const; where A should be the activity of potassium ions. In such a dilute solution, it can be considered that the potassium ion concentration and the potassium ion activity are approximately equal; from the formula Φ m =Φ const +0.0591*log a1(where Φ m is the membrane potential, a1 is the ion activity of the unknown solution outside the membrane) It is known that the theoretical value of k at 25°C is 0.059, and the measured value here is 0.044.

[0070] In summary, an ion-selective electrode that is selective for potassium ions was successfully fabricated on a flexible substrate, and the concentration of potassium ions in the solution can be accurately measured by the change in voltage. However, the slope of the standard working curve is lower than the theoretical value, and can only reach about 75% of the theoretical value. After analysis, it is believed that the following aspects of the experiment can be improved in subsequent experiments:

[0071] 1. Selection of anion shielding agent. After a certain amount of literature research, sodium tetraphenylborate, NaTPB, was selected as anion shielding agent. However, practice shows that sodium tetraphenylborate will form precipitation with potassium ions. Although the overall usage of sodium tetraphenylborate is small and its fluidity in the colloidal electrode membrane is not as strong as in the liquid, it will still cause the loss of potassium ions. In the future, potassium tetraphenylborate can be considered to replace sodium tetraphenylborate to avoid the influence of precipitation.

[0072] 2. Influence of the dripping method. In the experiment, the method of dripping KCl solution into the solution was adopted to obtain different concentration gradients; the method of measuring different solutions with the same electrode can eliminate the influence of disturbance during dripping, but considering that the concentration of KCl in sweat often changes continuously, it is more meaningful to measure the performance of different concentration gradients of the same solution.

[0073] Therefore, the present invention adopts the above-mentioned flexible wearable potassium ion detection sensor and its preparation method, replacing the traditional glass membrane + internal reference solution structure, greatly reducing the volume of the potassium ion selective electrode, realizing the miniaturization of the potassium ion sensor, enhancing the practicality, and broadening the scope of application.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A flexible wearable potassium ion detection sensor, characterized in that: The invention comprises an electrode, a liquid film and a substrate, wherein the liquid film covers the surface of the electrode, and the electrode is arranged on the substrate; the electrode comprises a three-electrode system or a two-electrode system; the three-electrode system comprises a working electrode, a reference electrode and a counter electrode; the two-electrode system comprises a working electrode and a reference electrode; the working electrode, the reference electrode and the counter electrode are prepared by a micro-nano processing method and arranged on the substrate, and the substrate is a flexible planar substrate or a flexible microneedle substrate; the flexible planar substrate comprises any one of polyethylene terephthalate, polyethylene naphthalate, polydimethylsiloxane, adhesive tape, paper, band-aid or cotton cloth, and the flexible microneedle substrate comprises any one of chitosan, polylactic acid and thermoplastic polyurethane elastomer rubber; The steps of preparing the working electrode and / or the counter electrode by the micro-nano processing method are: evaporating or sputtering to obtain a nano-layer of gold or platinum, and then electroplating on it to produce a Prussian blue layer to obtain a platinum / Prussian blue electrode or a gold / Prussian blue electrode; the steps of preparing the reference electrode by the micro-nano processing method are: sputtering or evaporating to produce a silver electrode, and then partially converting the silver into silver chloride through a chemical reaction in a ferric chloride solution to obtain a silver / silver chloride electrode; In the three-electrode system, the working electrode, the reference electrode and the counter electrode are arranged adjacent to each other, and the distance between the working electrode, the reference electrode and the counter electrode is set to 0.5-3 mm; in the two-electrode system, the working electrode and the reference electrode are arranged adjacent to each other, and the distance between the working electrode and the reference electrode is set to 0.5-3 mm; The liquid membrane includes liquid membrane A and liquid membrane B; liquid membrane A covers the surface of the working electrode, and liquid membrane B covers the surface of the reference electrode; the components of liquid membrane A include 2% w / w valinomycin, 0.5% w / w sodium tetraphenylborate, 32.7% w / w PVC polyvinyl chloride and 64.7% w / w dioctyl sebacate, and the components of liquid membrane B include polyvinyl butyral, sodium chloride and methanol.

2. A method for preparing a flexible wearable potassium ion detection sensor as claimed in claim 1, characterized in that: The following steps are involved: a. Making a flexible planar substrate or a flexible microneedle substrate; b. forming an electrode mold on the substrate, adding electrode materials into the corresponding electrode molds respectively, and drying to obtain electrodes; c. Take 20 μL of liquid membrane A solution, add it evenly onto the working electrode with a pipette, take 20 μL of liquid membrane B solution, add it evenly onto the reference electrode with a pipette, and then place the electrode in a 4°C refrigerator to dry for 12 hours to obtain a flexible wearable potassium ion detection sensor.

3. The preparation method according to claim 2, characterized in that: The electrode mold in step b is a mold for making an electrode shape. When the substrate is a flexible flat substrate, the overall electrode size of the working electrode, the reference electrode and the counter electrode is 1mm-10mm in diameter and 10-200μm in thickness; when the substrate is a flexible microneedle substrate, the working electrode, the reference electrode and the counter electrode are all rectangles formed by an array of cones, with a size of (1mm-10mm)×(5mm-2cm), a microneedle height of 300-1500μm, a bottom diameter of 100-500μm, a spacing range of 100-1000μm, and an electrode thickness of 50-300nm.

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