Low-resistance stretchable electrode and preparation method and application thereof

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Low resistance stretchable electrodes are prepared by ultrasonic treatment and patterned deposition. Combined with soft wires to connect them with heterosqualitative conductive glue, the problem of insufficient conductivity and tensile properties of flexible electrodes is solved, and stable signal transmission and multimodal physiological signal monitoring is achieved, which is suitable for wearable devices.

CN120376242APending Publication Date: 2025-07-25XIAMEN UNIV

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Patent Information

Application Number: CN202510574731.5
Authority / Receiving Office: CN · China
Patent Type: Applications(China)
Current Assignee / Owner
Filing Date: 2025-05-06
Publication Date: 2025-07-25

AI Technical Summary

Technical Problem

Existing flexible electrodes have shortcomings in conductivity, stretchability and process complexity, making it difficult to achieve large-scale production and stable interface connections, especially when used in wearable devices.

Method used

The conductive paste is mixed with solvent and ultrasonic treatment, and is patterned and deposited on the polymer substrate and annealed. It is connected with a soft wire to ensure the conductivity and tensile properties of the electrodes, and a stable interface connection is achieved through the heterosquamous conductive adhesive.

Benefits of technology

The prepared low-resistance stretchable electrode has excellent conductivity and tensile properties, and can transmit signals stably under dynamic conditions. It is suitable for multimodal physiological signal monitoring and meets the health monitoring needs of wearable devices.

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Abstract

The invention discloses a low-resistance stretchable electrode and a preparation method and application thereof, and relates to the field of flexible electronic devices. The conductive slurry and a solvent are mixed and subjected to ultrasonic treatment, then patterned deposition is performed on a polymer substrate, and finally annealing treatment is performed to prepare the low-resistance stretchable electrode. The prepared electrode has excellent tensile property, the uniaxial tensile limit of the electrode can reach 44%, meanwhile, the electrode has good conductivity, the resistance of the electrode with the width of 0.5 mm is about 3.8 ohm / cm, and the electrode is suitable for preparation of stretchable electrodes. The design of the electrode interface is combined with the characteristics of the substrate material, and stable transmission of electrode electric signals is ensured through bonding of the electrode and the conductive surface of the flexible flat cable. The electrode can be used for preparing a multi-mode physiological signal sensor and can monitor various physiological signals such as temperature, electrolyte, metabolite, nutrient substances and hormone. The method disclosed by the invention is simple and convenient to operate and controllable in process, and the prepared electrode has good stability and wide application prospect.

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Description

Technical Field

[0001] The present invention relates to the field of flexible electronic devices, and particularly to a low-resistance stretchable electrode and its preparation method and application. Background Art

[0002] The development of flexible electronic technology has enabled the rapid expansion of the applications of wearable devices in physiological monitoring, health management, etc. Among them, as one of the core components, flexible electrodes need to have high conductivity, good stretchability, and compatibility with human skin because they are in direct contact with human skin. Traditional preparation processes (such as coating, printing, etc.) have disadvantages such as complex processes and high costs, and it is difficult to meet the requirements of large-area and low-cost production. Especially in the design of electrode interfaces, how to effectively achieve a stable connection between the electrode and the signal transmission line is still a technical problem to be solved urgently.

[0003] Conductive pastes have become an ideal choice for preparing flexible electrodes due to their excellent conductivity, flexibility, and chemical stability. Conductive pastes are composed of conductive microparticles, binders, and solvents, and a conductive layer can be formed on a substrate by spraying, printing, etc. However, in actual preparation, the dispersion uniformity and adhesion of conductive pastes still face challenges, and improper process control may lead to problems such as uneven electrode thickness, insufficient conductivity and stretchability. Summary of the Invention

[0004] The purpose of the present invention is to solve the above problems in the prior art, such as poor conductivity, insufficient stretchability, complex processes, difficulty in large-scale production, and unstable interfaces, and to provide a low-resistance stretchable electrode and its preparation method and application. This electrode is simple to prepare, has excellent conductivity, good stretchability, and stable interface connection, and is particularly suitable for physiological signal monitoring in flexible wearable / implantable devices.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A preparation method of a low-resistance stretchable electrode, comprising the following steps:

[0007] 1) Mix a conductive paste with a solvent to obtain a mixture;

[0008] 2) Ultrasonically treat the mixture obtained in step 1) to uniformly disperse the conductive nanoparticles in the conductive paste in the solvent, obtaining a conductive dispersion liquid to prevent unevenness during the electrode preparation process;

[0009] 3) Pattern-deposit the conductive dispersion liquid obtained in step 2) on a polymer substrate to form a patterned electrode, wherein the solvent swells the polymer substrate, thereby enhancing the interfacial bonding force between the conductive nanoparticles and the polymer substrate;

[0010] 4) Anneal the patterned electrode obtained in step 3) to cure the polymer substrate to obtain the low-resistance stretchable electrode;

[0011] Wherein, the solvent is selected from one or a mixture of several of diester mixtures (such as DBE, etc.), toluene, acetone, isopropanol, methanol, dichloromethane, tetrahydrofuran, dimethyl sulfoxide, acetonitrile, n-hexane, ethanol.

[0012] The conductive paste includes silver paste, carbon paste or a combination thereof.

[0013] In the mixture of step 1), the mass fraction of the conductive paste is 30% - 50%.

[0014] The polymer substrate includes polyethylene terephthalate (PET), polyimide (PI), paper-based materials, polyurethane (PU), glass fiber reinforced plastics, polydimethylsiloxane (PDMS), polystyrene-butadiene block copolymer (SBS), hydrogenated polystyrene-butadiene block copolymer (SEBS), collagen, silk protein.

[0015] The patterned deposition is carried out by screen printing, spin coating, dip coating, dispensing, inkjet printing, knife coating, drop coating or spraying process.

[0016] The temperature of the annealing treatment is 70 - 150 °C, and the annealing time is 15 - 20 minutes.

[0017] A low-resistance stretchable electrode is prepared by the above preparation method.

[0018] An application of a low-resistance stretchable electrode for preparing a flexible sensor, which can monitor physiological signals such as temperature, electrolytes (such as sodium ions, calcium ions, potassium ions, chloride ions), metabolites (such as glucose, urea, lactic acid), nutrients and hormone sensors.

[0019] In the present invention, the interface of the flexible printed circuit board (FPCB) and the electrode is directly connected, and the FPCB serves as a signal transmission channel. The FPCB has the advantages of being thin, flexible and adaptable to various shapes. By directly connecting the FPCB to the interface part of the electrode, efficient signal transmission can be achieved.

[0020] The interface between the flexible printed circuit board and the electrode is mechanically strengthened and electrically connected through anisotropic conductive adhesive (ACF adhesive).

[0021] Compared with the prior art, the beneficial effects achieved by the technical solution of the present invention are:

[0022] 1. The present invention prepares a low-resistance stretchable electrode by ultrasonically dispersing a conductive paste and then depositing the dispersion on the surface of a substrate, and using a solvent to cause partial swelling of the substrate to increase the interaction between the conductive paste and the substrate. This method simplifies the process flow, and the prepared electrode has good conductivity, stretchability, and bend resistance.

[0023] 2. The electrode of the present invention has excellent flexibility and stretchability, overcomes the problems of easy fracture or failure of traditional electrodes in flexible applications, and significantly improves the service life and reliability of the electrodes.

[0024] 3. The electrode of the present invention has extremely high conductivity, can quickly respond and accurately detect physiological signals, and meets the requirements of high-precision monitoring.

[0025] 4. The present invention effectively solves the reliability problem of the connection at the soft-hard interface by combining a flexible printed circuit board (FPCB) with a conductive electrode and using an anisotropic conductive film (ACF film) as the connection medium.

[0026] 5. The low-resistance stretchable electrode prepared by the present invention can adhere well to the skin. Through good adaptation to organisms, this electrode can be used as part of a wearable device, ensuring signal stability during exercise. The preparation method of the electrode and interface of the present invention can be applied in the fields of biomedical and wearable technologies, and is suitable for multi-modal physiological signal monitoring, including monitoring various physiological parameters such as temperature, electrolytes, metabolites, nutrients, and hormones. The application scenarios are extensive and can meet the diverse health monitoring needs of modern times. Description of the Drawings

[0027] Figure 1 Schematic diagram of the preparation method of the low-resistance stretchable electrode and its interface prepared in Example 1.

[0028] Figure 2 Photographs of the low-resistance stretchable electrodes prepared in Example 1 and Example 2. Among them, the left figure is the low-resistance stretchable electrode prepared in Example 1, and the right figure is the low-resistance stretchable electrode prepared in Example 2.

[0029] Figure 3 SEM images of the low-resistance stretchable electrode prepared in Example 1. Among them, the left figure is the SEM image at a scale of 20 μm, and the right figure is the SEM image at a scale of 5 μm.

[0030] Figure 4 Photographs of the low-resistance stretchable electrode with an FPC interface prepared in Example 1 and a photograph of the measurement of the line width of the silver electrode.

[0031] Figure 5 Resistance values of the low-resistance stretchable electrode prepared in Example 1 and its interface after connection.

[0032] Figure 6 Real-time resistance change diagram of the low-resistance stretchable electrode prepared in Example 1 under stretching conditions.

[0033] Figure 7 Real-time resistance change diagram of the low-resistance stretchable electrode prepared in Example 1 under the condition of continuous 500 bends of 45°. Among them, the upper inset is a physical diagram of the equipment and sample for the bending test, and the lower inset is a partial enlarged view of the resistance change in the red box area (near about 300 - 320 cycles) in the main figure.

[0034] Figure 8 SEM diagram of the low-resistance stretchable electrode prepared in Example 2. Among them, the right figure is the SEM diagram under a scale of 20 μm, and the left figure is the SEM diagram under a scale of 5 μm.

[0035] Figure 9 Real-time resistance change diagram of the low-resistance stretchable electrode prepared in Example 2 under the condition of continuous 300 bends of 45°. Among them, the upper inset is a physical diagram of the equipment and sample for the bending test of the low-resistance stretchable electrode, and the lower inset is a partial enlarged view of the resistance change in the red box area (near about 100 - 120 cycles) in the main figure.

[0036] Figure 10 Performance test of the low-resistance stretchable electrode prepared in Example 2 for preparing pH, K + , NH4 + , dopamine sensing electrodes. Detailed implementation manners

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Therefore, the detailed descriptions in the embodiments of the present invention provided below are not intended to limit the scope of the claimed invention, but merely represent the selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

[0038] Example 1

[0039] Referring to Figure 1 the preparation process of, in this embodiment, the conductive paste used is conductive silver paste. Add 5 g of conductive silver paste into a reagent bottle, and then add 10 g of toluene using a disposable syringe. Then place it in an ultrasonic cleaner for ultrasonic treatment to disperse the conductive paste particles. The ultrasonic conditions are: ultrasonic power 500 W, ultrasonic temperature 30°C, and ultrasonic time 30 min to obtain a conductive dispersion liquid.

[0040] Attach a mask with a specific pattern to the SEBS substrate, and prepare a conductive electrode through the mask. Specifically, use a rubber dropper with a capacity of 5 mL to draw the prepared conductive dispersion liquid and add it into the spray gun. Spray evenly for 1 minute under a spraying pressure of 0.5 - 4 bar, then heat on a hot plate at 90 °C for 20 minutes, and then remove the mask to obtain a patterned low-resistance stretchable electrode.

[0041] Figure 2 The left middle figure is a physical picture of the prepared low-resistance stretchable electrode.

[0042] Figure 3 It is a picture of a scanning electron microscope (SEM) of the low-resistance stretchable electrode. The conductive network formed by the dispersion of silver nanoparticles provides a structural basis for stretchability.

[0043] Attach an anisotropic conductive film (ACF film) to the conductive surface of the flexible printed circuit board (FPCB) to increase the stability of the interface contact, and connect the flexible printed circuit board interface and the electrode interface to complete the interface preparation. Figure 4 Figure A in the middle is a physical picture of the prepared low-resistance stretchable electrode and its interface connection. Figure 4 Figure B in the middle is the width measurement of the electrode, and its line width can reach 0.5 mm. Use a multimeter to test the resistance value of the conductive path as Figure 5 shown, which is about 3.8 Ω / cm, achieving low-resistance patterning.

[0044] The prepared low-resistance stretchable electrode has excellent stretchability. As Figure 6 shown, monitor the resistance change of the low-resistance stretchable electrode under the stretching condition, and its ultimate tensile strain can reach 44%. Test the resistance change under the bending condition, and the data is as Figure 7 shown. After continuously bending at 45° for 500 times, test the resistance value of the electrode to remain stable.

[0045] Example 2

[0046] In this example, the conductive paste used is conductive carbon paste. Add 5 g of conductive carbon paste into a reagent bottle, and use a disposable syringe to add 15 g of toluene. Then, put the reagent bottle into an ultrasonic cleaner for ultrasonic treatment. The ultrasonic conditions are set as follows: ultrasonic power 450 W, ultrasonic temperature 25 °C, ultrasonic time 30 min, to obtain a uniformly dispersed conductive carbon paste particle dispersion liquid.

[0047] Place a mask with a specific pattern on the SEBS substrate. Use a 5 mL pipette to suck up the dispersion and inject it into the spray gun. Spray evenly for 2 minutes under a spraying pressure of 0.3 - 3 bar to form a uniform carbon coating. Then, heat the sprayed substrate on a hot plate at 110 °C for 15 minutes to volatilize the solvent in the dispersion, thereby achieving the deposition and curing of the conductive particles. Subsequently, remove the mask to obtain a patterned low-resistance stretchable electrode.

[0048] Figure 2 The right middle figure is a physical picture of the prepared low-resistance stretchable electrode. Figure 8 It is a SEM picture of the low-resistance stretchable electrode, where carbon particles and the binder are evenly dispersed on the substrate surface. Next, paste anisotropic conductive film (ACF film) on the conductive surface of the flexible printed circuit board (FPCB) interface, connect the FPCB interface with the electrode interface to complete the preparation of the conductive path interface. Test the change in resistance under bending conditions, and the data is as Figure 9 shown. After continuously bending at 45° for 300 times, the change in the resistance value of the electrode is small.

[0049] The electrode of the present invention is applicable to various physiological signal monitoring. The specific implementation is as follows. Three kinds of ion-selective membranes are respectively formed on the surface of the low-resistance stretchable electrode: (a) NH4 + ion-selective membrane, comprising: 1 wt% valinomycin, 32.2 wt% polyvinyl chloride (PVC), and 66.8 wt% bis(2-ethylhexyl) sebacate (DOS); (b) pH ion-selective membrane, comprising: 0.5 wt% potassium tetrakis(4-chlorophenyl)borate (KTClPB), 1 wt% tri(dodecyl)amine, 33.0 wt% PVC, and 65.5 wt% DOS; (c) K + ion-selective membrane, comprising: 2 wt% valinomycin, 0.5 wt% KTClPB, 32.8 wt% PVC, and 64.7 wt% DOS; Each ion-selective membrane is prepared by dissolving 100 mg of the above corresponding mixture in 1 mL of tetrahydrofuran (THF), and then coating and curing. Specifically, it is dropped onto the surface of the low-resistance stretchable electrode at a coating amount of 3 μL / cm² by a micropipette, and after curing at room temperature for 2 hours, it is used as the working electrode, and Ag / AgCl electrode is used as the reference electrode for open-circuit potential testing. Using a three-electrode system, the low-resistance stretchable electrode is used as the working electrode / counter electrode, and the surface is modified with Ag / AgCl as the reference electrode. A constant potential of 0.1 V (vs. Ag / AgCl) is applied for chronoamperometry testing to monitor dopamine, and the experimental results are as Figure 10 shown.

[0050] The present invention provides a method for fabricating a low-resistance stretchable electrode based on conductive paste patterning, aiming to achieve excellent electrical conductivity and stretchability to meet the requirements of multimodal physiological signal monitoring. This method involves mixing the conductive paste with a specific solvent and performing ultrasonic treatment to form a uniformly dispersed conductive particle dispersion. Using patterning technology, the dispersion is deposited on the surface of the substrate, and the solvent causes partial swelling of the substrate, thereby enhancing the interfacial bonding force between the conductive nanoparticles and the polymer substrate. After annealing, a low-resistance stretchable electrode is obtained. Using ACF adhesive, the electrode is bonded to the conductive surface of the flexible printed circuit board (FPCB) for stable connection, thereby ensuring the stable transmission of the electrode electrical signal and ensuring stable signal transmission during dynamic monitoring. This low-resistance stretchable electrode has excellent electrical conductivity and stretchability, is suitable for wearable physiological signal sensors, can monitor various physiological signals in real time and reliably, and has broad application prospects.

Claims

1. A preparation method of a low-resistance stretchable electrode, characterized in that, It includes the following steps: 1) Mix the conductive paste with a solvent to obtain a mixture; 2) Ultrasonically treat the mixture obtained in step 1) to uniformly disperse the conductive nanoparticles in the conductive paste in the solvent, obtaining a conductive dispersion; 3) Pattern-deposit the conductive dispersion obtained in step 2) on a polymer substrate to form a patterned electrode, wherein the solvent swells the polymer substrate, thereby enhancing the interfacial bonding force between the conductive nanoparticles and the polymer substrate; 4) Anneal the patterned electrode obtained in step 3) to cure the polymer substrate to obtain the low-resistance stretchable electrode; wherein the solvent is selected from one or a mixture of dibasic acid esters, toluene, acetone, isopropanol, methanol, dichloromethane, tetrahydrofuran, dimethyl sulfoxide, acetonitrile, n-hexane, ethanol.

2. The preparation method of a low-resistance stretchable electrode according to claim 1, characterized in that: The conductive paste includes silver paste, carbon paste or a combination thereof.

3. The preparation method of a low-resistance stretchable electrode according to claim 1, characterized in that: In the mixture of step 1), the mass fraction of the conductive paste is 30% - 50%.

4. The preparation method of a low-resistance stretchable electrode according to claim 1, characterized in that: The polymer substrate includes polyethylene terephthalate (PET), polyimide (PI), paper-based materials, polyurethane (PU), glass fiber reinforced plastics, polydimethylsiloxane (PDMS), polystyrene-butadiene block copolymer (SBS), hydrogenated polystyrene-butadiene block copolymer (SEBS), collagen, silk protein.

5. The preparation method of a low-resistance stretchable electrode according to claim 1, characterized in that: The pattern deposition is carried out by screen printing, spin coating, dip coating, dispensing, inkjet printing, scraping, drop coating or spraying processes.

6. The preparation method of a low-resistance stretchable electrode according to claim 1, characterized in that: The temperature of the annealing treatment is 70 - 150 °C, and the annealing time is 15 - 20 minutes.

7. A low-resistance stretchable electrode, characterized in that: Prepared by the preparation method according to any one of claims 1 - 6.

8. Use of a low-resistance stretchable electrode according to claim 7, characterized in that: For preparing a flexible sensor.

9. The application according to claim 8, characterized in that: Directly connect the interface of the flexible cable with the electrode, and the flexible cable serves as a signal transmission channel.

10. The application according to claim 9, characterized in that: The interface between the flexible cable and the electrode is mechanically strengthened and electrically connected through anisotropic conductive adhesive (ACF adhesive).