Flexible multi-parameter sweat sensor and method of making the same

Abstract

The application discloses a flexible multi-parameter sweat sensor and a preparation method thereof. + and K + electrode, a reference electrode, a counter electrode, and an insulating layer covering electrode leads. The preparation method adopts a screen printing process to form a silver / carbon conductive layer pattern, and then sequentially constructs sensitive layers of each electrode through electrodeposition, drop coating, physical adsorption and the like, wherein a mushroom-shaped gold nanowire@graphene oxide heterojunction is introduced into the glucose / lactic acid electrode as an enzyme adsorption functional material, the reference electrode is treated with ferric chloride to form an Ag / AgCl film and is coated with a PVB reference film containing NaCl. The application has the advantages of simple preparation process, low cost and batch production, good sensor flexibility, no conductive layer cracking and falling off phenomenon after deformation, and can accurately detect glucose, lactic acid, Na + , K + and environmental temperature in sweat, and has excellent selectivity.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano sensing, and specifically discloses a flexible multi-parameter sweat sensor and its preparation method. Background Technology

[0002] Abnormal concentrations of biochemical substances may be a manifestation of disease, such as excessively high glucose or sodium levels. + Concentration too low, K + Excessive concentrations may indicate diabetes, hyponatremia, or hyperkalemia. Therefore, the detection of biochemical concentrations is of great significance in disease diagnosis and prevention. Clinically, venous blood sampling is typically used to analyze the concentrations of these biochemical substances to assess an individual's health status. On the one hand, this process requires expensive specialized equipment and skilled technicians, increasing the financial burden on patients. On the other hand, venous blood sampling is an invasive procedure that requires skin puncture, causing significant psychological discomfort for patients, and carries a risk of infection. In recent years, non-invasive flexible electrochemical sweat sensors based on sweat analysis have shown great potential for non-invasive, real-time, and continuous detection of biochemical concentrations due to their excellent biocompatibility and flexibility. These sensors primarily detect relevant biochemical substances (such as glucose, lactic acid, cortisol metabolites, sodium, and other substances) in sweat. + K + and Ca 2+ The concentration of electrolytes (electrolytes).

[0003] Currently, most flexible sweat sensors can only detect the concentration of a single substance, thus failing to accurately and comprehensively assess an individual's health status. With the rapid development of flexible electronics technology, multiple working electrodes for biochemical substance detection can be integrated onto a flexible substrate to form an integrated, miniaturized flexible electrode array, enabling precise detection of various biochemical substance concentrations. The manufacturing technologies for these sensors mainly include MEMS fabrication, 3D printing, and screen printing. MEMS fabrication offers high reliability and precision, but its complex processing requires specialized high-precision equipment (such as coating machines, lithography machines, and etching machines), resulting in high costs and difficulty in mass production. 3D printing can rapidly manufacture flexible sensors with various complex shapes, but it has high requirements for raw materials and produces sensors with poor surface quality and low stability. In contrast, screen printing requires no specialized equipment, has a simple and easy manufacturing process, low production costs, and a short manufacturing cycle. More importantly, screen printing can mass-produce electrochemical sensor electrode arrays, and the resulting sensors can accurately detect the concentration of biochemical substances. Therefore, screen printing technology has certain advantages in the manufacture of electrochemical sensors, and can meet the needs of mass production and low cost.

[0004] Furthermore, the responsiveness and reliability of flexible sweat sensors to analytes are also critical issues that urgently need to be addressed. On the one hand, the sensor's responsiveness to analytes mainly relies on designing and fabricating nanomaterials with large specific surface areas, strong electron transport capabilities, and abundant active sites to increase the adsorption of oxidases, thereby improving the sensor's electron yield and transmission rate. On the other hand, because flexible sweat sensors need to adhere to the surface of human skin, they inevitably undergo deformations such as stretching, bending, or twisting. This can lead to cracks, warping, and detachment at the "solid / solid" interface between the flexible substrate, conductive film, and sensing material, thus affecting the stability of sensor performance and the accuracy of detection results. Therefore, designing a reasonable sensor structure and selecting a suitable flexible substrate to match the sensing material are crucial to ensure conformal contact between the sensor and the skin, maintaining good responsiveness and reliability during deformations such as stretching, bending, or twisting. Summary of the Invention

[0005] This invention has two objectives:

[0006] On the one hand, a flexible multi-parameter sweat sensor is provided, addressing the problems of most existing sweat sensors having single detection parameters, high manufacturing costs, and difficulty in mass production. This sensor utilizes a screen printing process to integrate a temperature sensor, a glucose sensing electrode, a lactic acid sensing electrode, and an all-solid-state sodium... + Selective electrode, all-solid-state K + Selector electrode, counter electrode, reference electrode, and electrode leads are integrated on a flexible PET substrate, enabling the measurement of temperature, glucose, lactic acid, and sodium in sweat. + and K + This technology enables multi-parameter detection; the preparation process is simple and easy to implement, low in cost and does not require special processing equipment, and can mass-produce sweat sensors, significantly improving the sensor preparation efficiency and reducing its manufacturing cost.

[0007] On the other hand, a method for fabricating the aforementioned flexible multi-parameter sweat sensor is provided. Addressing the issue of insufficient response capability in existing sensors, a mushroom-shaped gold nanowire@graphene oxide heterostructure is used as the functional material for adsorbing oxidases to construct the working electrode for glucose (or lactate) sensing. Its unique three-dimensional spatial structure and high electron transport capability provide more active sites for reliable adsorption of glucose oxidase (or lactate oxidase) and promote the rapid transfer of redox electrons from the enzyme's active site to the electrode, thus enhancing the sensor's response capability. This sensor can accurately detect temperature and the levels of glucose, lactate, and sodium in sweat. + K +The concentration exhibits good selectivity. During deformation, the conductive layer of the sensor's electrode array maintains good contact with the PET substrate, preventing cracking, warping, or detachment, thus ensuring the sensor retains good conductivity and exhibits excellent deformation capability.

[0008] This invention provides the following technical solution:

[0009] A flexible multi-parameter sweat sensor includes a bottom PET flexible substrate, a temperature sensor, a glucose sensing electrode, a lactic acid sensing electrode, and an all-solid-state sodium atomizer fixed on the top of the PET flexible substrate. + Selective electrode, all-solid-state K + The electrode comprises a selector electrode, a counter electrode, a reference electrode, and electrode pins, which are respectively connected to a temperature sensor, a glucose sensing electrode, a lactic acid sensing electrode, and an all-solid-state Na+ electrode. + Selective electrode, all-solid-state K + The selective electrode, counter electrode, and reference electrode are electrically connected; it also includes an electrical insulation layer, and the temperature sensor, glucose sensing working electrode, lactic acid sensing working electrode, and all-solid-state Na... + Selective electrode, all-solid-state K + The select electrode, counter electrode, reference electrode, and electrode pins are covered with an electrical insulating layer, which is used to achieve electrical insulation between the electrodes.

[0010] Preferably, the all-solid Na + Selective electrode, all-solid-state K + The conductive layers of the selector electrode, reference electrode, and electrode leads are formed by printing silver paste onto a flexible PET substrate using a screen printing process.

[0011] Preferably, the conductive layers of the temperature sensor, glucose sensing working electrode, lactic acid sensing working electrode, and counter electrode are formed by printing carbon paste onto a PET flexible substrate using a screen printing process.

[0012] A method for preparing the above-mentioned flexible multi-parameter sweat sensor includes the following steps:

[0013] Step 1: Clean the PET flexible substrate with anhydrous ethanol and deionized water in sequence using ultrasonic cleaning for 15 minutes, then let it air dry and wipe it with a non-woven cloth.

[0014] Step 2: Fix the lower end of the PET flexible substrate to the screen printing worktable;

[0015] Step 3: Place the mask A with the electrode pattern (i.e., the mask with all-solid-state Na) + Selective electrode, all-solid-state K +Selective electrode, reference electrode, and electrode lead pattern are fixed on a flexible PET substrate; silver paste is applied to a squeegee, which is then moved at a constant speed on mask A to form all-solid Na. + Selective electrode, all-solid-state K + Micropatterns were selected for the electrodes, reference electrodes, and electrode leads, and then the samples were placed in a vacuum drying oven at 120°C. o Keep at C for 50 minutes;

[0016] Step 4: Remove the PET flexible substrate with the silver electrode pattern, let it cool to room temperature, and then fix its lower end back onto the screen printing worktable.

[0017] Step 5: Fix the mask B with electrode patterns (i.e., patterns for the temperature sensor, glucose sensing working electrode, lactic acid sensing working electrode, and counter electrode) onto the PET flexible substrate; apply carbon paste to a squeegee and move the squeegee uniformly across mask B to form the micropatterns for the temperature sensor, glucose sensing working electrode, lactic acid sensing working electrode, and counter electrode. Then place it in a vacuum drying oven at 120°C. o Keep at C for 50 minutes;

[0018] Step 6: Remove the patterned PET flexible substrate and allow it to cool to room temperature to obtain the conductive layer of the integrated electrode array;

[0019] Step 7: Using the temperature sensor, glucose sensing working electrode, lactic acid sensing working electrode, and all-solid-state Na... + Selective electrode, all-solid-state K + Acrylic conformal coating is applied as an insulating layer to the select electrode, counter electrode, reference electrode, and electrode leads.

[0020] Step 8: Electrodeposit Prussian blue as a mediator layer on the working electrode for glucose sensing, with 0-30 deposition cycles; then, drop-coat 15 μL of mushroom-shaped gold nanowires@graphene oxide heterojunction and dry at room temperature; subsequently, physically adsorb 10 μL of glucose oxidase onto the surface of the heterojunction and dry at 4°C. o Dry at C; finally, wrap with a 3 μL Nafion ion exchange membrane to prevent glucose oxidase from detaching.

[0021] Step 9: Similarly, Prussian blue was electrodeposited on the working electrode for lactate sensing, with 0-30 deposition cycles; then, 15 μL of mushroom-shaped gold nanowires@graphene oxide heterojunction was drop-coated and dried at room temperature, followed by physical adsorption of 10 μL of lactate oxidase on the surface of the heterojunction and drying at 4°C. o Dry at C environment; finally, wrap with 3μL Nafion ion exchange membrane to prevent lactate oxidase from falling off;

[0022] Step 10: In all-solid-state Na+ 6 μL of Na was dropped onto the selective electrode. + Select membrane mixture, the Na + The selective membrane mixture was prepared by mixing 100 mg of sodium ion carrier X, sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, polyvinyl chloride, and dioctyl sebacate and dissolving them in 660 μL of tetrahydrofuran; wherein the mass fractions of sodium ion carrier X, sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, polyvinyl chloride, and dioctyl sebacate were 1%, 0.55%, 33%, and 65.45%, respectively.

[0023] Step 11: Similarly, in the all-solid-state K + 4 μL of K was dropped onto the selective electrode. + Select membrane mixture, the K + The membrane mixture was prepared by mixing 100 mg of valine, sodium tetraphenylborate, polyvinyl chloride, and dioctyl sebacate and dissolving them in 350 μL of cyclohexanone; wherein the mass fractions of valine, sodium tetraphenylborate, polyvinyl chloride, and dioctyl sebacate were 2%, 0.5%, 32.8%, and 64.7%, respectively.

[0024] Step 12: Drop 10 μL of ferric chloride solution (1 M concentration) onto the reference electrode Ag membrane and keep it for 1 min, then wash with deionized water and air dry at room temperature to form an Ag / AgCl membrane; drop 10 μL of reference membrane solution onto the Ag / AgCl membrane and dry at room temperature; the reference membrane solution is made by dissolving 79.1 mg of PVB and 50 mg of NaCl in 1 mL of methanol.

[0025] Preferably, the Prussian blue mesosome layer is electrodeposited using cyclic voltammetry, specifically including the following steps:

[0026] Step 1, prepare the solution: Dissolve FeCl3, K3Fe(CN)6, and KCl in 100 mL of HCl and stir continuously at 400 rpm; wherein, the concentration of FeCl3 is 2.5 mM, the concentration of K3Fe(CN)6 is 2.5 mM, the concentration of KCl is 100 mM, and the concentration of HCl is 100 mM.

[0027] The second step is the electrodeposition of Prussian blue: Using cyclic voltammetry, Prussian blue mediator layers are electrodeposited on the working electrodes for glucose sensing and lactic acid sensing, respectively, relative to the Ag / AgCl reference electrode. The potential scan range is 0V to +0.5V, and the scan rate is 20 mV / s. -1 Scanning circle number 0~30.

[0028] Preferably, the mushroom-shaped gold nanowires@graphene oxide heterostructure is prepared by a chemical reduction method, specifically including the following steps:

[0029] Step 1: The graphene oxide dispersion and PEI solution were ultrasonically treated separately, then mixed and ultrasonically treated again to amination the surface of the graphene oxide. The concentration of the graphene oxide dispersion was 1 mg / mL, the concentration of the PEI solution was 100 mg / mL, the ultrasonic power was 100 W, and the ultrasonic time was 30 min.

[0030] Step 2: First, sodium citrate, sodium borohydride, and chloroauric acid are mixed in deionized water to form an Au seed solution. Then, an aminated graphene oxide dispersion is added to allow the graphene oxide to fully adsorb the Au seeds. The concentrations of sodium citrate, sodium borohydride, and chloroauric acid are 5 mM.

[0031] Step 3: First, ascorbic acid, p-mercaptobenzoic acid, chloroauric acid, anhydrous ethanol, and deionized water are mixed to form an Au growth solution. Then, a graphene oxide dispersion with adsorbed Au seeds is added. After reacting for 10 minutes, the mixture is centrifuged, washed with deionized water, and dried at room temperature to obtain mushroom-shaped gold nanowires@graphene oxide heterostructures. The concentrations of ascorbic acid, p-mercaptobenzoic acid, and chloroauric acid are 100 mM, 10 mM, and 250 mM, respectively.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) Silver paste and carbon paste are printed on a flexible PET substrate using screen printing to form an integrated electrode array pattern. This process is simple and easy to implement, low in cost, and does not require special processing equipment. It can mass-produce sweat sensors, significantly improving the sensor's preparation efficiency and reducing its manufacturing cost. (2) During deformation, the conductive layer of the electrode array always maintains good contact with the PET substrate and will not crack, warp, or fall off, ensuring that the sensor maintains good conductivity. (3) The working electrode for glucose (or lactic acid) sensing uses mushroom-shaped gold nanowires@graphene oxide heterojunction as the functional material for adsorbing oxidase. Its unique three-dimensional spatial structure and high electron transport capacity provide more active sites for the reliable adsorption of glucose oxidase (or lactate oxidase) and promote the rapid transfer of redox electrons from the enzyme's active center to the electrode, which helps to enhance the sensor's response capability. (4) The sensor can accurately detect glucose, lactic acid, and Na+ in sweat. + K + The sensor can detect the concentration of glucose, lactic acid, and sodium simultaneously or selectively. It also exhibits good selectivity and deformability. + and K + Furthermore, the sensitive layer on the working electrode can be replaced with urease or Ca2+. 2+ Select membrane, Cl -Selective membranes, etc., are used for uric acid, calcium, etc. 2+ Cl - Detection of substances such as [list of substances]. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the flexible multi-parameter sweat sensor of the present invention.

[0035] Figure 2 This is an electron microscope image of the morphology of the mushroom-shaped gold nanowire@graphene oxide heterostructure according to an embodiment of the present invention.

[0036] Figure 3 This is a test diagram of the deformation capability of the conductive layer of the electrode array according to an embodiment of the present invention.

[0037] Performance test diagram of the temperature sensor according to an embodiment of the present invention, wherein: Figure 4(a) shows the response of the temperature sensor to different temperatures and the fitted line graph; Figure 4(b) shows the deformation capability test diagram of the temperature sensor.

[0038] Performance test diagram of the working electrode for glucose sensing according to an embodiment of the present invention, wherein: Figure 5(a) shows the current response of the working electrode for glucose sensing to glucose and the fitted line graph. Figure 5(b) shows the selectivity test diagram of the working electrode for glucose sensing; Figure 5(c) shows the test diagram of sweat glucose detection using the working electrode of the glucose sensor; Figure 5(d) shows the deformation capability test diagram of the working electrode used for glucose sensing.

[0039] Performance test diagram of the working electrode for lactic acid sensing according to an embodiment of the present invention, wherein: Figure 6(a) shows the current response of the working electrode for lactic acid sensing to lactic acid and the fitted line graph. Figure 6(b) shows the selectivity test diagram of the working electrode for lactic acid sensing; Figure 6(c) shows the test results of sweat lactic acid detection using the working electrode of the lactic acid sensor; Figure 6(d) shows the deformation capability test diagram of the working electrode used for lactic acid sensing.

[0040] Performance test diagram of the all-solid-state Na+ selective electrode of this invention, wherein: Figure 7(a) shows the potential response of the all-solid-state Na+ selective electrode to Na+ and the fitted line graph; Figure 7(b) shows the selectivity test results of the all-solid-state Na+ selective electrode; Figure 7(c) shows the sweat Na+ detection test results using an all-solid-state Na+ selective electrode; Figure 7(d) shows the deformation capability test diagram of the all-solid-state Na+ selective electrode.

[0041] Performance test diagrams of the all-solid-state K+ selective electrode according to an embodiment of the present invention, wherein: Figure 8(a) shows the potential response of the all-solid-state K+ selective electrode to K+ and the fitted line graph; Figure 8(b) shows the selectivity test results of the all-solid-state K+ selective electrode; Figure 8(c) shows the sweat K+ detection test results using an all-solid-state K+ selective electrode; Figure 8(d) shows the deformation capability test diagram of the all-solid-state K+ selective electrode.

[0042] Among them, 1: PET flexible substrate; 2: temperature sensor; 3: working electrode for glucose sensing; 4: working electrode for lactic acid sensing; 5: all-solid-state Na+ selective electrode; 6: all-solid-state K+ selective electrode; 7: counter electrode; 8: reference electrode; 9: electrode pin; 10: electrical insulation layer. Detailed Implementation

[0043] To better illustrate the present invention, embodiments of the invention will be described below with reference to the accompanying drawings, detailing their technical solutions. Obviously, the described embodiments are only a part of the present invention, and not a complete list of all embodiments. Furthermore, the various embodiments are not entirely unrelated and can be combined and applied according to actual circumstances, but should be based on the premise that those skilled in the art can implement them.

[0044] Based on the embodiments of the present invention, if abnormal phenomena or experimental results contrary to common sense occur when the embodiments are combined and applied, it should be considered that such a combination scheme does not exist and is not within the scope of protection claimed by the present invention. However, other combination schemes obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0045] See Figure 1 The present invention discloses a flexible multi-parameter sweat sensor, comprising a bottom PET flexible substrate 1, a temperature sensor 2 fixed on the upper end of the PET flexible substrate 1, a glucose sensing working electrode 3, a lactic acid sensing working electrode 4, and an all-solid-state Na+ sensor. + Select electrode 5, all-solid-state K + Selector electrode 6, counter electrode 7, reference electrode 8, and electrode pin 9, wherein electrode pin 9 is respectively connected to temperature sensor 2, glucose sensing working electrode 3, lactic acid sensing working electrode 4, and all-solid-state Na+. + Select electrode 5, all-solid-state K +Selective electrode 6, counter electrode 7, and reference electrode 8 are electrically connected; it also includes an electrical insulation layer 10, and the temperature sensor 2, glucose sensing working electrode 3, lactic acid sensing working electrode 4, and all-solid-state Na + Select electrode 5, all-solid-state K + The selector electrode 6, counter electrode 7, reference electrode 8, and electrode pin 9 are coated with an electrical insulating layer 10, which is used to achieve electrical insulation between the electrodes.

[0046] The present invention also provides a method for preparing the above-mentioned flexible multi-parameter sweat sensor, comprising the following steps:

[0047] 1) The PET film was ultrasonically cleaned with anhydrous ethanol and deionized water for 15 minutes in sequence, and then air-dried to form a flexible PET substrate.

[0048] 2) Fix the lower end of the PET flexible substrate 1 onto the screen printing worktable;

[0049] 3) The mask A with the electrode pattern (i.e., with all-solid Na) + Select electrode 5, all-solid-state K + The pattern of the selective electrode 6, reference electrode 8, and electrode pins 9 is fixed above the PET flexible substrate; silver paste is applied to a squeegee, which is then moved at a constant speed on mask A to form all-solid Na. + Selective electrode, all-solid-state K + The micropatterns of the selector electrode, reference electrode, and electrode leads are placed in a vacuum drying oven at 120°C. o Maintain at C for 50 minutes;

[0050] 4) Remove the PET flexible substrate with the silver electrode pattern, let it cool to room temperature, and then fix its lower end back onto the screen printing worktable.

[0051] 5) Fix the mask B with electrode patterns (i.e., patterns for temperature sensor 2, glucose sensing working electrode 3, lactic acid sensing working electrode 4, and counter electrode 7) onto the PET flexible substrate; apply carbon paste to a squeegee and move the squeegee uniformly across mask B to form micro-patterns for the temperature sensor, glucose sensing working electrode, lactic acid sensing working electrode, and counter electrode; place it in a vacuum drying oven at 120°C. o Maintain at C for 50 minutes;

[0052] 6) Remove the patterned PET flexible substrate and cool it to room temperature to obtain the conductive layer of the integrated electrode array;

[0053] 7) Temperature sensor 2, glucose sensing working electrode 3, lactic acid sensing working electrode 4, all-solid-state Na + Select electrode 5, all-solid-state K+ Acrylic conformal coating is applied to the selector electrode 6, reference electrode 8, counter electrode 7 and electrode pin 9 as an insulating layer 10;

[0054] 8) A Prussian blue mediator layer was electrodeposited on the working electrode 3 for glucose sensing, with a deposition cycle of 0-30 cycles; 15 μL of mushroom-shaped gold nanowires@graphene oxide heterojunction was drop-coated onto the Prussian blue surface and dried at room temperature; then 10 μL of glucose oxidase was physically adsorbed onto the surface of the heterojunction and dried at 4°C. o Drying at C; finally, coating the oxidase surface with a 3 μL Nafion ion exchange membrane to prevent enzyme detachment;

[0055] 9) Similarly, a Prussian blue mediator layer was electrodeposited on the working electrode 4 for lactic acid sensing, with a deposition cycle of 0-30 cycles; 15 μL of mushroom-shaped gold nanowires@graphene oxide heterojunction was drop-coated onto the Prussian blue surface and dried at room temperature; then 10 μL of lactase was physically adsorbed onto the surface of the heterojunction and dried at room temperature. o Drying at C environment; finally, coating the surface of lactase with a 3μL Nafion ion exchange membrane to prevent enzyme detachment;

[0056] 10) In all-solid-state Na + 6 μL of Na was dropped onto electrode 5. + Select membrane mixture, the Na + The membrane mixture was prepared by mixing and dissolving 100 mg of sodium ion carrier X, sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, polyvinyl chloride, and dioctyl sebacate in 660 μL of tetrahydrofuran; wherein, according to the mass fraction, sodium ion carrier X, sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, polyvinyl chloride, and dioctyl sebacate accounted for 1%, 0.55%, 33%, and 65.45%, respectively.

[0057] 11) In all-solid-state K + 4 μL of K was dropped onto electrode 6. + Select membrane mixture, the K + The membrane mixture was prepared by mixing 100 mg of valine, sodium tetraphenylborate, polyvinyl chloride, and dioctyl sebacate and dissolving them in 350 μL of cyclohexanone; wherein, according to the mass fractions, valine, sodium tetraphenylborate, polyvinyl chloride, and dioctyl sebacate accounted for 2%, 0.5%, 32.7%, and 64.7%, respectively.

[0058] 12) Drop 10 μL of ferric chloride solution onto the Ag membrane of the reference electrode 8 and keep it for 1 min, then wash it with deionized water and air dry it at room temperature to form an Ag / AgCl membrane; drop 10 μL of reference membrane solution onto the Ag / AgCl membrane; the concentration of the ferric chloride solution is 1 M, and the reference membrane solution is a mixture of PVB and NaCl dissolved in methanol, wherein PVB is 79.1 mg, NaCl is 50 mg, and methanol is 1 mL.

[0059] 13) The Prussian blue mediator layer was electrodeposited using cyclic voltammetry, specifically including the following steps: Step 1, Solution preparation: FeCl3, K3Fe(CN)6, and KCl were dissolved in 100 mL of HCl and continuously stirred at 400 rpm; the concentrations of FeCl3, K3Fe(CN)6, KCl, and HCl were 2.5 mM, 100 mM, and 100 mM, respectively. Step 2, Prussian blue electrodeposition: Using cyclic voltammetry, the Prussian blue mediator layer was electrodeposited on the glucose sensing working electrode and the lactic acid sensing working electrode, respectively, relative to the Ag / AgCl reference electrode. The potential scan range was 0 V to +0.5 V, and the scan rate was 20 mV / s. -1 Scanning circle number 0~30.

[0060] 14) Mushroom-shaped gold nanowires@graphene oxide heterostructures were prepared by a chemical reduction method, specifically including the following steps: Step 1: The graphene oxide dispersion and PEI solution were ultrasonically treated separately, then mixed and ultrasonically treated again to amination the surface of the graphene oxide. The concentration of the graphene oxide dispersion was 1 mg / mL, the concentration of the PEI solution was 100 mg / mL, the ultrasonic power was 100 W, and the ultrasonic time was 30 min. Step 2: Sodium citrate, sodium borohydride, and chloroauric acid were first mixed in deionized water to form an Au seed solution, and then the amination-treated graphene oxide dispersion was added to allow the graphene oxide to fully adsorb the Au seeds. The concentrations of sodium citrate, sodium borohydride, and chloroauric acid were 5 mM and 0.1 M respectively. In the third step, ascorbic acid, p-mercaptobenzoic acid, chloroauric acid, anhydrous ethanol, and deionized water were mixed to form an Au growth solution. Then, a graphene oxide dispersion containing adsorbed Au seeds was added. After reacting for 10 minutes, the mixture was centrifuged, washed with deionized water, and dried at room temperature to obtain mushroom-shaped gold nanowires@graphene oxide heterostructures. The concentrations of ascorbic acid, p-mercaptobenzoic acid, and chloroauric acid were 100 mM and 10 mM respectively. The microstructure of the mushroom-shaped gold nanowires@graphene oxide heterostructures is shown in [reference needed]. Figure 2 .

[0061] In one possible implementation, the flexible multi-parameter sweat sensor obtained by the present invention is subjected to temperature, glucose, lactic acid, and sodium...+ K + The response test also tested its selectivity and deformability, as well as its response to glucose, lactic acid, and sodium in sweat. + K + Concentration analysis.

[0062] Example 1: Deformation capability test of conductive layer of electrode array.

[0063] The resistance of a screen-printed electrode array was measured after being repeatedly bent 0, 20, 40, 60, 80, and 100 times with an outer diameter of 2.5 cm. Figure 3 As shown, after being repeatedly bent 100 times, the resistance of the silver film and the carbon film remained basically unchanged, indicating that the conductive layer of the electrode array prepared by screen printing technology has good deformability.

[0064] Example 2: Temperature sensor response to temperature.

[0065] A multi-parameter sweat sensor was fixed on a constant-temperature heating platform. The resistance response step curves of the temperature sensor to different temperatures were measured using constant-voltage technology. Based on this, the relationship between temperature and resistance was fitted, as shown in Figure 4(a). Clearly, the resistance value of the temperature sensor steadily increases with increasing temperature. The sensitivity of the temperature sensor was determined to be 5.8 ± 0.7 Ω·m based on the fitted line. o C -1 The detection range is 20. o C~95 o C.

[0066] Using a 2.5cm diameter outer cylinder as the bending axis, the multi-parameter sweat sensor was repeatedly bent 0, 30, 60, and 90 times. The resistance response step curves of the temperature sensor to different temperatures were measured, and the relationship between temperature and resistance was fitted. Based on this, the relationship curve between the number of bends and the sensitivity of the temperature sensor was obtained, as shown in Figure 4(b). Obviously, as the number of bends increases, the sensitivity of the temperature sensor does not change significantly, indicating that the temperature sensor has good deformation capability.

[0067] Example 3: Response of the working electrode for glucose sensing to glucose.

[0068] Based on a three-electrode system, the current-time response method was used to measure the current response of the working electrode for glucose sensing to different glucose concentrations. Specifically, under a bias voltage of +0.8V (i.e., the voltage of the working electrode for glucose sensing relative to the reference electrode), the three-electrode system was placed in 100mL of PBS solution and stirred at 400rpm until the background current reached a stable state. Then, 200μL of a 250mM glucose solution was added to the PBS solution every 50s, and the response current was collected. The above steps were repeated until the response current saturated, thus obtaining the current-time response step curve of the working electrode for glucose sensing. Based on this, the relationship between glucose concentration and response current was fitted, as shown in Figure 5(a). Obviously, the working electrode for glucose sensing exhibits a rapid and stable current response to glucose, and the sensitivity reaches 27.5μA·mM. -1 ·cm -2 The linear range is 0~8.0mM, and the detection limit is 49.0μM.

[0069] At a bias voltage of +0.8V, the response current of the glucose sensing working electrode to 3mM glucose, 5mM lactic acid, 0.2mM ascorbic acid, 0.2mM uric acid, 0.2mM phenylalanine, 100mM NaCl, 10mM KCl, 1mM CaCl2, and 0.2mM MgCl2 was measured using the current-time response method, as shown in Figure 5(b). Clearly, the glucose sensing working electrode exhibits a significant current response only to glucose, while showing almost no response to other interfering substances (maximum relative response less than 5.0%). Therefore, the glucose sensing working electrode demonstrates good selectivity.

[0070] At a bias voltage of +0.8V, the response of the glucose sensing electrode to glucose in artificial sweat (sample 1 and sample 2) was measured using the current-time response method. Sample 1 contained 75 μM glucose, 5 mM lactic acid, and 10 mM Na+. + 1mMK + 1mM Ca 2+ 0.2mM Mg 2+ Sample 1 contained 0.2 mM urea and 0.2 mM ascorbic acid; Sample 2 contained 150 μM glucose, 7.5 mM lactate, and 100 mM sodium. + 10mM K + 1mM Ca 2+ 0.2mM Mg 2+The sample contained 0.2 mM urea and 0.2 mM ascorbic acid. Combining Figures 5(a) and 5(c), the glucose concentrations in Sample 1 and Sample 2 were calculated to be 79.2 μM and 153.5 μM, respectively, with relative errors of 5.6% and 2.3% compared to the glucose concentration in artificial sweat. Therefore, the working electrode for glucose sensing can detect the glucose concentration in sweat.

[0071] Using a 2.5 cm diameter outer cylinder as the bending axis, the multi-parameter sweat sensor was repeatedly bent 0, 20, 40, 60, 80, and 100 times. Cyclic voltammetry curves of the glucose sensing working electrode in a 3 mM glucose solution were measured, and the changes in the second oxidation peak (the peak corresponding to the glucose oxidation process) were recorded. The relationship between the number of bends and the relative change of the second oxidation peak was obtained, as shown in Figure 5(d). Clearly, as the number of bends increased, the second oxidation peak did not change significantly, indicating that the glucose sensing working electrode has good deformability.

[0072] Example 4: The response of the working electrode for lactic acid sensing to lactic acid.

[0073] Similarly, based on a three-electrode system, the current-time response method was used to measure the current response of the working electrode for lactic acid sensing to different concentrations of lactic acid. Specifically, under a bias voltage of +0.6V (i.e., the voltage of the working electrode for lactic acid sensing relative to the reference electrode), the three-electrode system was placed in 100mL of PBS solution and stirred at 400rpm until the background current reached a stable state. Then, 80μL of 2.5M lactic acid solution was added to the PBS solution every 50s, and the response current was collected. The above steps were repeated until the response current saturated, thus obtaining the current-time response step curve of the working electrode for lactic acid sensing. Based on this, the relationship between lactic acid concentration and response current was fitted, as shown in Figure 6(a). Obviously, the working electrode for lactic acid sensing exhibits a fast and stable current response to lactic acid, and the sensitivity reaches 2.9μA·mM. -1 ·cm -2 Linear range: 0~10.0 mM; detection limit: 3.2 × 10⁻⁶ mM. -4 μM.

[0074] At a bias voltage of +0.6V, the response current of the working electrode for lactic acid sensing to 5mM lactic acid, 3mM glucose, 0.2mM ascorbic acid, 0.2mM uric acid, 0.2mM phenylalanine, 100mM NaCl, 10mM KCl, 1mM CaCl2, and 0.2mM MgCl2 was measured using the current-time response method, as shown in Figure 6(b). Clearly, the working electrode for lactic acid sensing exhibits a significant current response only to lactic acid, while showing almost no response to other interfering substances (maximum relative response less than 8.5%). Therefore, the working electrode for lactic acid sensing possesses good selectivity.

[0075] The response of the working electrode for lactic acid sensing to lactic acid in artificial sweat (sample 1 and sample 2) was measured using the current-time response method at a bias voltage of +0.6V. Sample 1 contained 5 mM lactic acid, 75 μM glucose, and 10 mM Na+. + 1mM K + 1mM Ca 2+ 0.2mM Mg 2+ Sample 1 contained 0.2 mM urea and 0.2 mM ascorbic acid; Sample 2 contained 7.5 mM lactate, 150 μM glucose, and 100 mM sodium. + 10mM K + 1mM Ca 2+ 0.2mM Mg 2+ The samples contained 0.2 mM urea and 0.2 mM ascorbic acid. Combining Figures 6(a) and 6(c), the lactic acid concentrations in Sample 1 and Sample 2 were calculated to be 4.62 mM and 6.86 mM, respectively, with relative errors of -7.6% and -8.5% compared to the lactic acid concentration in artificial sweat. Therefore, the working electrode for lactic acid sensing can detect the lactic acid concentration in sweat.

[0076] Using a 2.5 cm diameter outer cylinder as the bending axis, the multi-parameter sweat sensor was repeatedly bent 0, 20, 40, 60, 80, and 100 times. Cyclic voltammetry curves of the working electrode for lactic acid sensing in a 10 mM lactic acid solution were measured, and the changes in the oxidation peak (the peak corresponding to the lactic acid oxidation process) were recorded. The relationship between the number of bends and the relative change of the oxidation peak was obtained, as shown in Figure 6(d). Clearly, as the number of bends increased, the oxidation peak did not change significantly, indicating that the working electrode for lactic acid sensing has good deformability.

[0077] Example 5: All-solid Na + Select electrode pair Na + The response.

[0078] Based on a two-electrode system, the open-circuit potential method is used to measure all-solid-state Na. + Selective electrode for different concentrations of Na+ The response potential. Specifically, the two electrode system is sequentially placed in 10... -8 M, 10 -7 M, 10 -6 M, 10 -5 M, 10 -4 M, 10 -3 M, 10 -2 M, 10 -1 In NaCl solutions of M, 1M, and 6.17M (saturated solution), the response potential corresponding to each concentration was collected for 30 seconds, and the NaCl potential was fitted accordingly. + The relationship between the logarithm of Na concentration and the response potential is shown in Figure 7(a). Clearly, as Na... + As the concentration increases, solid Na + The selected electrode exhibits a uniform and stable increase in potential response, with a sensitivity of 57.9 mV·decade. -1 (The theoretical sensitivity value calculated using the Nernst equation is 59.2 mV·decade) -1 (Very close), linear range 10 -5.35 ~6.17M, with a minimum detection limit of 4.5μM.

[0079] Measurement of all-solid-state Na using the open-circuit potential method + Selective electrodes were used to treat 100mM Na. + 10mM K + 1mM Ca 2+ 0.2mM Mg 2+ 10mM CO3 2- 10mM PO4 3- The response potentials of 5 mM glucose, 5 mM lactic acid, 0.2 mM urea, and 0.2 mM ascorbic acid are shown in Figure 7(b). Clearly, the all-solid Na... + Selective electrode only for Na + It exhibits a significant potential response, but almost no response to other interfering substances (maximum relative response less than 1.3%). Therefore, all-solid-state Na + The selected electrode exhibits good selectivity.

[0080] Measurement of all-solid-state Na using the open-circuit potential method + Selective electrode for Na in artificial sweat (sample 1 and sample 2) + The response potential. Sample 1 contains 10 mM Na. + 1mM K + 1mM Ca 2+ 0.2mM Mg 2+Sample 1 contained 5 mM lactate, 75 μM glucose, 0.2 mM urea, and 0.2 mM ascorbic acid; Sample 2 contained 100 mM Na. + 10mM K + 1mM Ca 2+ 0.2mM Mg 2+ The samples contained 7.5 mM lactic acid, 150 μM glucose, 0.2 mM urea, and 0.2 mM ascorbic acid. Referring to Figures 7(a) and 7(c), the Na content in samples 1 and 2 was calculated. + The concentrations were 9.8 mM and 100.7 mM, with relative errors of -2.0% and 0.7% compared to the lactic acid concentration in artificial sweat, respectively. Therefore, the all-solid Na... + Selective electrodes can detect sodium in sweat. + concentration.

[0081] Using a 2.5cm diameter outer cylinder as the bending axis, the multi-parameter sweat sensor was repeatedly bent 0, 20, 40, 60, 80, and 100 times to measure the all-solid sodium content. + Selective electrode for different concentrations of Na + The response potential of Na was fitted. + The relationship between the logarithm of concentration and the response potential was used to calculate the sensitivity, thus obtaining the relationship between the number of bends and the sensitivity, as shown in Figure 7(d). Clearly, as the number of bends increases, the sensitivity of all-solid Na... + The sensitivity of the selective electrode changed only slightly, indicating that the all-solid-state Na + The selected electrode has good deformation capability.

[0082] Example 6: All-solid-state K + Select electrode pair K + The response.

[0083] Similarly, based on a two-electrode system, the open-circuit potential method is used to measure K in the all-solid state. + Selective electrode pairing for different K concentrations + The response potential. Specifically, the two electrode system is sequentially placed in 10... -6 M, 10 -5 M, 10 -4 M, 10 -3 M, 10 -2 M, 10 -1 In KCl solutions of M, 1M, and 4.24M (saturated solution), the response potential corresponding to each concentration was collected for 30 seconds, and the KCl value was fitted accordingly. + The relationship between the logarithm of concentration and the response potential is shown in Figure 8(a). Clearly, as K... + With increasing concentration, solid K +The selected electrode exhibits a uniform and stable increase in potential response, with a sensitivity of 59.4 mV·decade. -1 (The theoretical sensitivity value calculated using the Nernst equation is 59.2 mV·decade) -1 (Very close), linear range 10 -4.51 ~4.24M, with a minimum detection limit of 30.9μM.

[0084] Measurement of K in all solid-state systems using the open-circuit potential method + Selective electrodes were applied to 10 mM K. + 100mM Na + 1mM Ca 2+ 0.2mM Mg 2+ 10mM CO3 2- 10mM PO4 3- The response potentials of 5 mM glucose, 5 mM lactate, 0.2 mM urea, and 0.2 mM ascorbic acid are shown in Figure 8(b). Clearly, the all-solid K... + Electrode selection is only for K + It exhibits a significant potential response, while showing almost no response to other interfering substances (maximum relative response below 7.3%). Therefore, the all-solid-state K + The selected electrode exhibits good selectivity.

[0085] Measurement of K in all solid-state systems using the open-circuit potential method + Selective electrode for K in artificial sweat (sample 1 and sample 2) + The response potential. Sample 1 contains 1 mM K + 10mM Na + 1mM Ca 2+ 0.2mM Mg 2+ Sample 1 contained 5 mM lactate, 75 μM glucose, 0.2 mM urea, and 0.2 mM ascorbic acid; Sample 2 contained 10 mM K. + 100mM Na + 1mM Ca 2+ 0.2mM Mg 2+ 7.5 mM lactic acid, 150 μM glucose, 0.2 mM urea, and 0.2 mM ascorbic acid. Combining Figures 8(a) and 8(c), the K values ​​in Sample 1 and Sample 2 were calculated. + The concentrations were 0.97 mM and 9.6 mM, respectively, with relative errors of -3.0% and -4.0% compared to the lactic acid concentration in artificial sweat. Therefore, the all-solid K + Selective electrodes can detect potassium in sweat. + concentration.

[0086] Using a 2.5cm diameter outer cylinder as the bending axis, the multi-parameter sweat sensor was repeatedly bent 0, 20, 40, 60, 80, and 100 times to measure the K-force in the solid state. + Selective electrode pairing for different K concentrations + The response potential and fitted K + The relationship between the logarithm of concentration and the response potential was used to calculate the sensitivity, thus obtaining the relationship between the number of bends and the sensitivity, as shown in Figure 8(d). Clearly, as the number of bends increases, the Kconcentration of the all-solid state increases. + The sensitivity of the selected electrode remained essentially unchanged, indicating that the all-solid-state K... + The selected electrode has good deformation capability.

[0087] In summary, this invention provides a flexible multi-parameter sweat sensor and its fabrication method. A screen printing process is used to print silver paste and carbon paste as conductive layers on a flexible PET substrate, forming an integrated electrode array pattern. This process is simple, cost-effective, and requires no specialized processing equipment, allowing for mass production of sweat sensors. This significantly improves the sensor's fabrication efficiency and reduces manufacturing costs. During deformation, the conductive layer of the electrode array maintains good contact with the PET substrate, preventing cracking, warping, or detachment, ensuring the sensor maintains good conductivity. The working electrode for glucose (or lactic acid) sensing uses mushroom-shaped gold nanowires@graphene oxide heterojunctions as the functional material for adsorbing oxidases. Its unique three-dimensional structure and high electron transport capacity provide more active sites for reliable adsorption of glucose oxidase (or lactate oxidase) and promote rapid transfer of redox electrons from the enzyme's active center to the electrode, enhancing the sensor's response capability. The sensor can accurately detect glucose, lactic acid, and sodium in sweat. + K + The sensor can detect the concentration of glucose, lactic acid, and sodium simultaneously or selectively. It also exhibits good selectivity and deformability. + and K + Furthermore, the sensitive layer on the working electrode can be replaced with urease or Ca2+. + Select membrane, Cl - Selective membranes, etc., are used for uric acid, calcium, etc. + Cl - Detection of substances such as [list of substances].

[0088] The above description is merely illustrative of the core content of this invention and should not be construed as limiting the invention. Any modifications made in accordance with the principles of this invention should be included within the scope of protection of the claims.

Claims

1. A flexible multi-parameter sweat sensor, characterized in that, The flexible multi-parameter sweat sensor includes a bottom PET flexible substrate (1), a temperature sensor (2) fixed on the upper end of the PET flexible substrate (1), a glucose sensing working electrode (3), a lactic acid sensing working electrode (4), and an all-solid-state Na+ sensor. + Select electrode (5), all-solid-state K + Select electrode (6), counter electrode (7), reference electrode (8), and electrode pin (9), wherein the electrode pin (9) is connected to the temperature sensor (2), the glucose sensing working electrode (3), the lactic acid sensing working electrode (4), and the all-solid-state Na+ electrode, respectively. + Select electrode (5), all-solid-state K + The selective electrode (6), counter electrode (7), and reference electrode (8) are electrically connected; an electrical insulation layer (10) is also included. The temperature sensor (2), glucose sensing working electrode (3), lactic acid sensing working electrode (4), and all-solid Na + Select electrode (5), all-solid-state K + The select electrode (6), counter electrode (7), reference electrode (8) and electrode pin (9) are covered with an electrical insulating layer (10), which is used to achieve electrical insulation between the electrodes.

2. The flexible multi-parameter sweat sensor according to claim 1, characterized in that: The all-solid Na + Select electrode (5), all-solid-state K + The conductive layer of the select electrode (6), reference electrode (8) and electrode pin (9) is silver paste printed on a PET flexible substrate (1).

3. The flexible multi-parameter sweat sensor according to claim 1, characterized in that: The conductive layer of the temperature sensor (2), glucose sensing working electrode (3), lactic acid sensing working electrode (4), and counter electrode (7) is carbon paste printed on a PET flexible substrate (1).

4. A method for preparing the flexible multi-parameter sweat sensor according to claims 1-3, characterized in that, Includes the following steps: Step 1: Clean the PET flexible substrate (1) with anhydrous ethanol and deionized water in sequence using ultrasonic cleaning for 15 minutes, then let it air dry and wipe it with a non-woven cloth. Step 2: Fix the lower end of the PET flexible substrate (1) onto the screen printing worktable; Step 3: Add all-solid Na + Select electrode (5), all-solid-state K + A mask A containing the patterns of the selector electrode (6), reference electrode (8), and electrode pins (9) is fixed above a PET flexible substrate (1); silver paste is applied to a squeegee, and the squeegee is moved at a constant speed on mask A to form all-solid Na. + Select electrode (5), all-solid-state K + Micropatterns were selected for the electrode (6), reference electrode (8), and electrode pins (9), and then placed in a vacuum drying oven at 120°C. o Keep at C for 50 minutes; Step 4: Take the PET flexible substrate (1) processed in step 3 out of the vacuum drying oven and cool it to room temperature, then fix its lower end on the screen printing worktable again; Step 5: Fix the mask B with the pattern of temperature sensor (2), glucose sensing working electrode (3), lactic acid sensing working electrode (4), and counter electrode (7) on the PET flexible substrate (1); apply carbon paste to a squeegee and move the squeegee at a constant speed on the mask B to form the micropattern of temperature sensor (2), glucose sensing working electrode (3), lactic acid sensing working electrode (4), and counter electrode (7), and then place it in a vacuum drying oven at 120°C. o Keep at C for 50 minutes; Step 6: Remove the PET flexible substrate (1) processed in step 5 from the vacuum drying oven and cool it to room temperature to obtain the conductive layer of the integrated electrode array; Step 7: In the temperature sensor (2), glucose sensing working electrode (3), lactic acid sensing working electrode (4), all-solid Na + Select electrode (5), all-solid-state K + Acrylic conformal coating is applied as an insulating layer (10) to the selective electrode (6), counter electrode (7), reference electrode (8) and electrode pin (9). Step 8: Prussian blue was electrodeposited as a mediator layer on the working electrode (3) for glucose sensing; then, 15 μL of mushroom-shaped gold nanowires@graphene oxide heterojunction was drop-coated and dried at room temperature, followed by physical adsorption of 10 μL of glucose oxidase on the surface of the heterojunction and drying at 4°C. o Dry at C; finally, wrap with a 3 μL Nafion ion exchange membrane to prevent glucose oxidase from detaching. Step 9: Prussian blue was electrodeposited on the working electrode (4) for lactic acid sensing; then, 15 μL of mushroom-shaped gold nanowires@graphene oxide heterojunction was drop-coated and dried at room temperature, followed by physical adsorption of 10 μL of lactate oxidase on the surface of the heterojunction and drying at 4°C. o Dry at C environment; finally, wrap with 3μL Nafion ion exchange membrane to prevent lactate oxidase from falling off; Step 10: In all-solid-state Na + 6 μL of Na was dropped onto the selective electrode (5). + Select membrane mixture, the Na + The membrane mixture was prepared by mixing 100 mg of sodium ion carrier X, sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, polyvinyl chloride, and dioctyl sebacate and dissolving them in 660 μL of tetrahydrofuran. Step 11: Similarly, in the all-solid-state K + 4 μL of K was dropped onto the selective electrode (6). + Select membrane mixture, the K + The membrane mixture was prepared by mixing 100 mg of valine, sodium tetraphenylborate, polyvinyl chloride, and dioctyl sebacate and dissolving them in 350 μL of cyclohexanone. Step 12: Drop 10 μL of ferric chloride solution onto the Ag membrane of the reference electrode (8) and keep it for 1 min, then wash it with deionized water and air dry it at room temperature to form an Ag / AgCl membrane; drop 10 μL of reference membrane solution onto the Ag / AgCl membrane and dry it at room temperature.

5. The preparation method according to claim 4, characterized in that: The Prussian blue mesosome layer was electrodeposited using cyclic voltammetry, specifically including the following steps: Step 1, prepare the solution: Dissolve FeCl3, K3Fe(CN)6, and KCl in 100 mL of HCl and stir continuously at 400 rpm; wherein, the concentration of FeCl3 is 2.5 mM, the concentration of K3Fe(CN)6 is 2.5 mM, the concentration of KCl is 100 mM, and the concentration of HCl is 100 mM. The second step is electrodeposition of Prussian blue: Prussian blue is electrodeposited on the glucose sensing working electrode (3) and the lactic acid sensing working electrode (4) relative to the Ag / AgCl reference electrode using cyclic voltammetry. The potential scanning range is 0V to +0.5V, the scanning rate is 20mV / s, and the number of scanning cycles is 0 to 30.

6. The preparation method according to claim 4, characterized in that: The mushroom-shaped gold nanowire@graphene oxide heterostructure was prepared by a chemical reduction method, specifically including the following steps: Step 1: The graphene oxide dispersion and PEI solution were ultrasonically treated separately, then mixed and ultrasonically treated again, and finally stirred continuously at 1200 rpm for 12 h to amination the surface of graphene oxide. Step 2: First, mix sodium citrate, sodium borohydride, and chloroauric acid in deionized water to form an Au seed solution, and then add an aminated graphene oxide dispersion to allow the graphene oxide to fully adsorb the Au seeds. Step 3: First, ascorbic acid, p-mercaptobenzoic acid, chloroauric acid, and anhydrous ethanol are mixed in deionized water to form an Au growth solution. Then, graphene oxide dispersion with adsorbed Au seeds is added. After reacting for 10 minutes, the mixture is centrifuged, washed with deionized water, and dried at room temperature to finally obtain mushroom-shaped gold nanowires@graphene oxide heterojunctions.

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