Flexible high-sensitivity glucose concentration sensing electrode as well as batch preparation method and application thereof
By preparing copper nanostructures and loading palladium clusters in a sweat sensor using in-situ electrochemical deposition, the problems of limited sensor sensitivity and high fabrication complexity were solved, achieving efficient and low-cost glucose concentration detection suitable for wearable devices.
Patent Information
- Application Number
- CN202511076023.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-01
- Publication Date
- 2025-11-18
AI Technical Summary
Existing sweat glucose sensors suffer from limitations in sensitivity, high manufacturing complexity, and high cost during material synthesis and integration. Furthermore, the lack of stable chemical bonding between the sensing medium and the conductive substrate leads to a decrease in catalytic efficiency.
Copper nanostructures were rapidly prepared on conductive carbon layers using in-situ electrochemical deposition, and palladium clusters were loaded onto their surfaces to form stable ohmic contacts, thereby improving glucose oxidation activity, simplifying the preparation process, and avoiding the use of polymer binders such as Nafion films.
It achieves highly sensitive glucose concentration detection with short response time and low cost, making it suitable for large-scale production. Furthermore, the sensor works directly in a sweat environment, exhibiting good stability and specificity.
Smart Images
Figure CN120971533A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of sensor and detection instrument, and relates to a flexible high-sensitivity glucose concentration sensing electrode, which realizes glucose sensing function by using an electrode surface catalytic medium to oxidize glucose into gluconolactone to generate a current response. BACKGROUND
[0002] There is a strong correlation between the glucose concentration in human sweat and the glucose concentration in blood. Therefore, by real-time monitoring of the glucose concentration in human sweat, qualitative assessment of blood glucose level can be achieved. This online sensing technology has great potential for wide application in the contemporary society facing high prevalence of diabetes. In particular, some wearable and flexible sweat sensors can continuously track glucose dynamics, providing valuable insights into the physiological state of the wearer. This non-invasive device not only eliminates the discomfort brought by traditional blood sampling methods, but also greatly reduces the risk of blood-borne infections, thus attracting considerable research attention.
[0003] In view of the fact that the glucose concentration in sweat of healthy individuals and diabetic patients is usually between 10 and 300 μM (where M represents mol L -1 ), and the amount of sweat secreted under normal physiological conditions is relatively limited, detection of trace glucose requires a sensing medium with abnormally high reactivity. Current research work mainly focuses on the synthesis and optimization of these sensing materials, including enzyme systems and non-enzyme nanostructures. These media catalyze the oxidation of glucose to produce a measurable electrochemical current, the size of which can be used as an indicator of the glucose concentration in sweat. Recent progress has been made in the use of strategies such as element doping and structural engineering to improve catalytic performance, either by reducing the activation energy barrier or by increasing the density of active sites on the surface of the sensing medium microstructure. These improvements have significantly improved the sensitivity of the sensor, with some sensors having a detection limit (LOD) as low as 0.025 μM. The dynamic range of these optimized sensors now fully includes the physiological concentration range of glucose in sweat.
[0004] However, some studies also suggest that the overall reaction in electrochemical systems using these materials as working electrodes is often limited by the diffusion of glucose in solution. Therefore, further improvement in sensor performance by simply enhancing the intrinsic sensitivity of the material can only yield limited returns. More critically, these complex sensing media are often not directly synthesizable at the electrode surface, requiring additional transfer and immobilization steps to integrate them onto the working electrode. Due to the lack of stable chemical bonding between the sensing material and the conductive substrate, auxiliary adhesion strategies such as the use of Nafion films or polymer adhesives are often employed. However, these binders partially obstruct the active catalytic sites or introduce additional interfacial resistance between the sensing layer and the electrode, thus reducing the overall catalytic efficiency of the sensing medium. Furthermore, the transfer and immobilization process introduces additional manufacturing complexity and cost, posing significant challenges to the scalability and cost-effective production of commercial wearable sweat glucose sensors.
[0005] In this work, we present an efficient approach to fabricate high-sensitivity electrodes with enhanced catalytic activity for glucose detection in human sweat. Further studies show that copper nanostructures with high current density, good selectivity, and low cost can be assembled in situ on the conductive carbon layer of the working electrode within tens of seconds through a fast electrochemical deposition process. The resulting Cu nanostructures form a stable ohmic contact with the underlying conductive layer, establishing a low-resistance interface that facilitates efficient electron transfer. This promotes the formation of active catalytic sites with special reactivity for glucose oxidation. Through comparative analysis of Cu nanostructures prepared under constant-current and constant-voltage deposition conditions, it is found that Cu nanosheets prepared under constant-current deposition conditions have superior electron transport properties. Although the Cu nanoflower electrode is not optimal in response to low-concentration glucose changes, we are inspired by previous studies that show that doping controllable Pd in a Cu matrix can significantly reduce the chemical adsorption energy of hydrogen, thus improving the catalytic performance of the hydrogen evolution reaction. On this basis, we hypothesize that similar electronic structure modification can improve the glucose oxidation kinetics. Experimental results show that this loading method effectively improves the glucose oxidation rate of the prepared electrode, thus enhancing the response. SUMMARY
[0006] In view of the above technical problems existing in the prior art, the purpose of the present application is to provide a flexible high-sensitivity glucose concentration sensing electrode and a batch preparation method and application thereof. The present application utilizes the principle that copper material can be rapidly in-situ deposited at a lower voltage, and combines the reduction of adsorption energy of cluster loading for glucose adsorption, to manufacture a flexible high-sensitivity glucose concentration sensing electrode. The electrode surface catalytic medium is used to oxidize glucose to glucose lactone to generate current response, so as to realize the glucose sensing function. The sweat sensing electrode in the present application solves the technical problems of other sweat sensors, such as the need for a protective layer covering the electrode, the need for transferring sensitive materials, high preparation cost, long time consumption and the like.
[0007] The technical scheme adopted by the present application is as follows:
[0008] A flexible high-sensitivity glucose concentration sensing electrode comprises a piece of smooth and flat insulating substrate and a printed conductive three-electrode on the surface of the insulating substrate, the conductive three-electrode comprises a working electrode, a counter electrode and a reference electrode arranged at intervals, the surface of the working electrode is deposited with copper nanomaterial structure, and palladium clusters are loaded on the surface of the copper nanomaterial structure, and the basic structure is as shown in the accompanying Figure 1 The external circuit is connected to the glucose concentration sensing electrode by wires; when the sensor is in a sweat environment containing glucose, the sweat directly diffuses to the surface of the electrode, and the glucose molecules in the sweat are adsorbed on the surface of the copper nanomaterial, the copper element is oxidized to a metastable state and oxidizes the adsorbed glucose molecules to glucose lactone; the charge transfer generated in the redox process is displayed on the external circuit.
[0009] Further, the smooth and flat insulating substrate has a stable resistivity of not less than 10 8 Ω·m, which can be a flexible or completely rigid insulating material; the selected materials include but are not limited to: flexible films such as polyimide, polydimethylsiloxane or polyethylene terephthalate, or rigid film sheets such as quartz, glass, ruby, sapphire, resin or single crystal silicon wafer with silicon oxide insulating layer.
[0010] The present application further discloses a batch preparation method of the flexible high-sensitivity glucose concentration sensing electrode, comprising the following steps:
[0011] S1: selecting a smooth and flat insulating film sheet as an insulating substrate;
[0012] S2: first solidify the mask plate on the silk screen, etch the pattern of the conductive three-electrode on the mask plate; then cover the silk screen with the mask plate on the insulating substrate, print a layer of silver conductive layer by silk screen mask, then cover a layer of conductive carbon paste on the silver conductive layer of the working electrode and the counter electrode part to form the working electrode and the counter electrode respectively, then smear the NaClO solution with a mass concentration of 0.2%-0.8% on the surface of the silver electrode of the reference electrode part, and carry out chlorination reaction in the air atmosphere at room temperature, so as to obtain the Ag / AgCl reference electrode;
[0013] S3: in-situ electrochemical deposition is adopted to deposit the copper nanomaterial on the surface of the working electrode;
[0014] S4: the palladium cluster is loaded on the surface of the copper nanomaterial.
[0015] Further, the specific steps of the in-situ electrochemical deposition in step S3 are as follows: the working electrode printed by the silk screen mask is used as the substrate for depositing copper and as the cathode, that is, only the negative electrode of the power supply is connected to the working electrode as the cathode for in-situ electrochemical deposition, and a copper sheet is used as the anode counter electrode and connected to the positive electrode of the power supply, the electrolyte is an aqueous solution containing CuSO4, H2SO4 and CH3COOH, and the copper nanomaterial is deposited on the surface of the cathode by adopting the constant current deposition method.
[0016] Further, in the in-situ electrochemical deposition in step S3, the concentrations of the components in the electrolyte are respectively 0.3-0.5 mol / L of CuSO4, 1.2-1.8 mol / L of H2SO4 and 0.08-0.2 mol / L of CH3COOH, the constant current is 0.005-0.01 A, and the constant current deposition time is 20-60 s.
[0017] Further, in step S4, the palladium cluster is uniformly distributed on the surface of the working electrode. The deposition preparation is achieved by adopting nano printing, physical vapor deposition, chemical vapor deposition, block self-assembly and the like.
[0018] Further, in step S4, the palladium cluster is prepared by the gas phase cluster beam deposition technology, and the specific process is as follows: the cluster beam deposition equipment is vacuumized, a Pd target deposition source is used, Ar gas is used as the sputtering gas and buffer gas for beam deposition, the Pd nanocluster is deposited on the surface of the copper nanomaterial, the sputtering power of the Pd target material is adjusted to 10-15 W, the Pd deposition rate is maintained at 0.05-0.2 A / s, and the deposition time is 10-30 min.
[0019] The application further discloses application of the flexible high-sensitivity glucose concentration sensing electrode in detection of trace glucose concentration in sweat, and the application detection method comprises the following processes:
[0020] 1) Place the glucose concentration sensing electrode in glucose environments of different concentrations, record the electrode current changes in glucose environments of different concentrations through the external circuit, fit the response relationship, and input it into the external circuit to complete the calibration of the hydrogen sensor.
[0021] 2) Place the calibrated glucose concentration sensing electrode in a sweat environment containing trace amounts of glucose, and read the current glucose concentration in the environment through an external circuit display to realize the application of the glucose sensor.
[0022] Furthermore, in the above-mentioned application detection method, the glucose concentration is detected by the sensing electrode in a 0.08-0.12M NaOH solution.
[0023] The sweat glucose sensor described in this invention can be manufactured efficiently and at low cost, while exhibiting good stability and glucose sensing performance. It effectively avoids the use of polymers such as Nafion membranes as adhesives for sensitive materials, making it suitable for large-scale industrial production.
[0024] The working principle of the flexible, highly sensitive glucose concentration sensing electrode described in this invention is as follows: The surface of the sensing electrode is immersed in the solution to be tested. After a certain voltage is applied to the electrode, the elemental copper CuO on the surface of the working electrode is first oxidized to divalent Cu(II) ions, and further oxidized to metastable trivalent Cu(III) ions. Cu(III) has a strong oxidizing ability and can oxidize glucose to gluconolactone on the electrode surface, converting the charge generated by the reaction into a detectable current signal. The palladium clusters loaded on the surface of the copper nanostructure can significantly reduce the adsorption energy of glucose, improve the mass transfer ability of glucose molecules at the electrode-solution interface, and optimize the glucose concentration detection limit of the sensing electrode. The working principle is described in the appendix. Figure 2 Brief presentation.
[0025] Compared with the prior art, the beneficial effects achieved by the present invention are:
[0026] (1) The highly sensitive sweat sensor in the sweat environment of the present invention can sense and monitor the changes in glucose concentration in sweat in real time, and has the advantages of high sensitivity and short response time.
[0027] (2) The core components of the sensor are made of copper nanomaterials deposited in situ by electrochemical deposition, which are highly efficient and inexpensive.
[0028] (3) The introduction of palladium clusters significantly improves the sensing performance of the electrode;
[0029] (4) The sensor can work directly in a sweat environment without the need for polymer protection procedures such as Nafion membrane. Attached Figure Description
[0030] Figure 1 is a structural schematic diagram of the flexible high-sensitivity glucose concentration sensing electrode according to the present application;
[0031] wherein 1 is an insulating substrate, 2 is a screen-printed three-electrode system, 3 is a copper nanomaterial working electrode, and 4 is a palladium cluster.
[0032] Figure 2 is a basic working principle diagram of the sensor, and the core is that copper catalyzes oxidation of glucose molecules into gluconolactone;
[0033] Figure 3 is a scanning tunneling microscope topography diagram of the copper nanomaterial;
[0034] Figure 4 is a current response of the sensor to different concentrations of glucose and a standard curve;
[0035] Figure 5 is a current response curve before and after deposition of the palladium cluster;
[0036] Figure 6 is an anti-interference performance diagram of the sensor. DETAILED DESCRIPTION
[0037] The following examples further illustrate the present application, but should not be construed as limiting the present application. Modifications and substitutions to the methods, steps or conditions described herein are considered to be within the scope of the present application. If not specifically mentioned, the technical means used in the examples are conventional means known to those skilled in the art.
[0038] The flexible high-sensitivity glucose concentration sensing electrode according to the present application comprises a piece of smooth and flat insulating substrate 1 and a conductive three-electrode 2 printed on the surface of the insulating substrate 1, wherein the conductive three-electrode 2 comprises a working electrode, a counter electrode and a reference electrode arranged at intervals, the surface of the working electrode is deposited with a copper nanomaterial structure 3, and a palladium cluster 4 is loaded on the surface of the copper nanomaterial structure.
[0039] Example 1
[0040] The preparation process and application results of a high-sensitivity glucose sensor working in a sweat environment are described in detail below, which comprises the following steps:
[0041] Step 1, select a completely rigid insulating material with a smooth surface as an insulating substrate. Here, the rigid insulating substrate is a PET with a thickness of 0.2 mm, and the stable resistivity is about 10 9 Ω·m;
[0042] Step 2, three-electrode system is prepared by screen printing method: first, three kinds of electrode mask plate are solidified on the screen, then a silver electrode with a diameter of 3 mm is screen printed on PET as a conductive layer to enhance the conductivity of the whole electrode, then a conductive carbon paste with a diameter of 5 mm is covered on the silver electrode of the working electrode and the counter electrode to eliminate the interference of the silver electrode on the detection, then a small amount of 0.5% NaClO solution is applied to the surface of the silver electrode of the reference electrode, the NaClO solution fully wets the surface of the silver electrode, and then the chlorination reaction is carried out in the air atmosphere at room temperature, and the Ag / AgCl reference electrode is obtained;
[0043] Step 3, a 20*40*25mm electrolytic cell is prepared by using light-cured 3D printing technology as a reaction container, and the working electrode prepared by screen printing in step 2 is used as the substrate for depositing copper (cathode), that is, only the negative electrode of the power supply is connected to the working electrode as the in-situ electrochemical deposition cathode, and a 2*2cm copper sheet is used as the anode (anode) and connected to the positive electrode of the power supply. The solvent of the electrolyte is water, and the concentration of each solute is: CuSO4(0.4mol / L), H2SO4(1.5mol / L) and CH3COOH(0.1mol / L). Among them, acetic acid is added as a hydrogen bubble stabilizer to facilitate the formation of a loose and porous three-dimensional structure by sacrificing hydrogen bubbles, and the distance between the cathode and the anode is kept at 2cm during constant current deposition. The deposition constant current set by the constant potential instrument during constant current deposition is 0.008A, and the constant current deposition time is 35s. The copper nanomaterial obtained by constant current deposition uniformly covers the surface of the carbon electrode of the working electrode.
[0044] Step 3, after the constant current deposition of the copper nanomaterial is completed, the whole electrode is marked as SPE-Cu electrode sensor.
[0045] Step 4, finally, the copper nanomaterial surface is loaded with palladium clusters by using a cluster beam deposition device. First, the electrode sheet after constant current deposition is placed in the magnetron sputtering gas deposition chamber, and the working electrode is directly opposite to the beam direction to uniformly receive the clusters. The gas pressure in the chamber is vacuumed to 5*10 -4 Pa, and then the deposition is started. Pd target material deposition source is used, Ar gas is used as the sputtering gas and buffer gas for beam deposition, the flow rates of the sputtering gas and the buffer gas are 70sccm and 60sccm respectively, and the Ar as the sputtering gas is continuously ionized into Ar +And bombard Pd target material makes metal atoms absorb energy from the original lattice, the high energy metal atoms after the exchange of energy with the buffer gas fusion growth into clusters, clusters in the vacuum pump under the driving of the gas flow on the surface of the copper nanometer material loaded on the working electrode. Adjust the sputtering power of Pd target material to 12W, so that the Pd deposition rate is maintained at 0.09A / s, the deposition time is 20min, and the sample is stored in a dry box after deposition. After the fourth step, the micrograph of the copper nanometer material loaded with palladium clusters is shown in the accompanying Figure 3 It can be seen that the copper material we deposited is a nanoflower structure formed by stacking sheets, and the palladium clusters are uniformly covered on the surface of the copper material. Figure 3
[0046] After the fourth step, the entire electrode is deposited by gas phase cluster beam deposition technology, and the SPE-Cu-Pd electrode sensor is marked.
[0047] In the fifth step, the SPE-Cu-Pd electrode sensor obtained in the fourth step is tested for amperometric response in a higher glucose concentration range at an optimal potential of 0.6V in a 0.1M NaOH solution. The test process is to add standard glucose solution every certain time to increase the total glucose concentration of the test system. Each time the total glucose concentration is increased by 0.1mM. The stepwise current response of the sensor with increasing glucose concentration is shown in the accompanying Figure 4 It can be seen that the test electrode current changes with the gradient of the solution concentration to form a stable stepwise rise. The standard curve shows that the current and concentration form a good linear relationship. The corresponding relationship between current intensity and glucose concentration is I(mA) = 0.016 + 0.145C(mM). It can be concluded that the minimum detection limit of the SPE-Cu-Pd electrode is about 1.6μM. Figure 4 The process of adding standard glucose solution at different intervals is shown in the accompanying Figure 4 It can be seen that the test electrode current changes with the gradient of the solution concentration to form a stable stepwise rise. The standard curve shows that the current and concentration form a good linear relationship. The corresponding relationship between current intensity and glucose concentration is I(mA) = 0.016 + 0.145C(mM). It can be concluded that the minimum detection limit of the SPE-Cu-Pd electrode is about 1.6μM.
[0048] In the sixth step, the solution is increased by 0.01mM of glucose concentration each time under the same solution and 0.6V potential conditions as in the fifth step. The current response curves of the SPE-Cu electrode sensor in the third step and the SPE-Cu-Pd electrode sensor in the fourth step are compared. The detection comparison results are shown in the accompanying Figure 5 It can be seen that the introduction of palladium clusters significantly improves the response performance of the electrode to low concentration glucose. Figure 5
[0049] Step 7, the specificity of the target detection and long-term stability of the sensor using the SPE-Cu-Pd electrode is a key factor for the glucose sensor to be used in practice. Metabolic products such as lactic acid (LA), uric acid (UA) and ascorbic acid (AA) often coexist with glucose in sweat, and the concentrations of these substances are much lower than that of glucose, but the reducing property of ascorbic acid and fructose and the rapid electron transfer ability of uric acid and the like will interfere with the electrochemical detection of glucose. Therefore, it is crucial to study the anti-interference ability of the sensor. The interference test is achieved by adding 0.1 mM glucose, 10 μM fructose, uric acid (UA), acetaminophen, ascorbic acid (AA), dopamine (DA), L-cysteine and lactic acid (LA) in sequence in 0.1 mM NaOH solution at a reaction voltage of 0.6 V (v.s. AgCl / Ag) for amperometric testing. The test results are shown in FIG. 8, and the addition of interfering substances has no effect on the current signal of the sensor, indicating that the Cu-SPE electrode does not have catalytic reaction ability for other substances commonly found in sweat, can resist the interference of other common substances in blood, and has good specific detection ability. Figure 6 The addition of interfering substances has no effect on the current signal of the sensor, indicating that the Cu-SPE electrode does not have catalytic reaction ability for other substances commonly found in sweat, can resist the interference of other common substances in blood, and has good specific detection ability.
Claims
1. A flexible, highly sensitive glucose concentration sensing electrode, characterized in that... It includes a smooth and flat insulating substrate (1) and a conductive three-electrode (2) printed on the surface of the insulating substrate (1). The conductive three-electrode (2) includes a working electrode, a counter electrode and a reference electrode arranged at intervals. A copper nanomaterial structure (3) is deposited on the surface of the working electrode, and palladium clusters (4) are loaded on the surface of the copper nanomaterial structure.
2. The flexible, highly sensitive glucose concentration sensing electrode according to claim 1, characterized in that... The insulating substrate (1) has a stable resistivity of not less than 10. 8 Ω·m, which is made of flexible film or rigid film. The flexible film is selected from polyimide, polydimethylsiloxane or polyethylene terephthalate, and the rigid film is selected from quartz, glass, ruby, sapphire, resin or monocrystalline silicon wafer with silicon oxide insulating layer.
3. The flexible, highly sensitive glucose concentration sensing electrode according to claim 2, characterized in that... The insulating substrate (1) is made of polyimide, polydimethylsiloxane or polyethylene terephthalate flexible film.
4. The method for mass production of a flexible, highly sensitive glucose concentration sensing electrode according to claim 1, characterized in that... Includes the following steps: S1: Select a smooth and flat insulating film as the insulating substrate; S2: First, solidify the mask template on the screen and etch the pattern of the conductive three electrodes (2) on the mask template; then cover the screen with the mask template on the insulating substrate, print a layer of silver conductive layer on the screen mask, and then cover the working electrode and the counter electrode with a layer of conductive carbon paste on the silver conductive layer of the working electrode and the counter electrode respectively. Then, apply a NaClO solution with a mass concentration of 0.2%-0.8% to the surface of the silver electrode of the reference electrode and carry out a chlorination reaction at room temperature in an air atmosphere to obtain the Ag / AgCl reference electrode. S3: Copper nanomaterials are deposited and loaded onto the surface of the working electrode using in-situ electrochemical deposition. S4: Palladium clusters loaded on the surface of copper nanomaterials (4).
5. A method for mass production of a flexible, highly sensitive glucose concentration sensing electrode according to claim 4, characterized in that... The specific steps of in-situ electrochemical deposition in step S3 are as follows: a working electrode printed with a screen mask is used as the substrate for copper deposition, that is, only the negative terminal of the power supply is connected to the working electrode as the cathode for in-situ electrochemical deposition, and another copper sheet is set as the anode counter electrode and connected to the positive terminal of the power supply. The electrolyte is an aqueous solution containing CuSO4, H2SO4 and CH3COOH. Copper nanomaterials are deposited on the cathode surface by constant current deposition.
6. The method for mass production of a flexible, highly sensitive glucose concentration sensing electrode according to claim 4, characterized in that... In step S3, the concentrations of each component in the electrolyte are CuSO4 0.3-0.5 mol / L, H2SO4 1.2-1.8 mol / L and CH3COOH 0.08-0.2 mol / L, respectively. The constant current is 0.005-0.01 A, and the constant current deposition time is 20-60 s.
7. A method for mass production of a flexible, highly sensitive glucose concentration sensing electrode according to claim 4, characterized in that... In step S4, the palladium clusters (4) are uniformly distributed on the surface of the working electrode and deposited by nanoprinting, physical vapor deposition, chemical vapor deposition or block self-assembly.
8. A method for mass production of a flexible, highly sensitive glucose concentration sensing electrode according to claim 7, characterized in that... In step S4, palladium clusters (4) are prepared by vapor phase cluster beam deposition technology. The specific process is as follows: the cluster beam deposition equipment is evacuated, Pd target material is used as the deposition source, and Ar gas is used as the sputtering gas and buffer gas for beam deposition, so that Pd nano clusters are deposited on the surface of copper nanomaterials; the sputtering power of Pd target material is adjusted to 10-15W, the Pd deposition rate is maintained at 0.05-0.2A / s, and the deposition time is 10-30min.
9. The application of the flexible, highly sensitive glucose concentration sensing electrode according to claim 1 in the detection of trace glucose concentration in sweat.
10. The application according to claim 8, characterized in that... Its application detection method includes the following process: 1) Place the glucose concentration sensing electrode in glucose environments of different concentrations, record the changes in electrode current in glucose environments of different concentrations through the external circuit, fit the response relationship, and input it into the external circuit to complete the calibration of the hydrogen sensor. 2) Place the calibrated glucose concentration sensing electrode in a sweat environment containing trace amounts of glucose, and read the current glucose concentration in the environment through an external circuit display to realize the application of the glucose sensor.