Flexible wearable electrostatic spinning flexible electrode based on liquid metal

Abstract

The invention relates to a flexible wearable liquid metal-based electrostatic spinning flexible electrode patch as well as a preparation method and application thereof, and belongs to the crossing field of an electromyographic signal acquisition technology and a screen printing technology. Specifically, an ink electrode is printed on electrostatic spinning by utilizing a silk-screen printing technology, so that the high conductivity of the electrode is ensured while people feel comfortable in use, and an electrophysiological signal can be better detected. The invention discloses a wearable electrostatic spinning flexible electrode patch with flexibility based on liquid metal. The electrode patch can stably collect signals and ensure high-quality electromyogram recording, and has a better signal to noise ratio, so that a reliable guarantee is provided for an electromyogram signal collection system. Through the preparation method adopted by the invention, the obtained flexible electrode patch has high conductivity and good biological adaptability, keeps excellent signal acquisition performance, and can be matched with common electromyographic signal acquisition equipment in the current market.

Description

Technical Field

[0001] The present invention relates to a flexible wearable liquid metal-based electrospinning flexible electrode, and in particular to a flexible wearable liquid metal-based electrospinning flexible electrode patch and its preparation method and application, which belongs to the intersection of electromyographic signal acquisition technology and screen printing technology. Specifically, the ink electrode is printed on the electrospinning by screen printing technology, which makes people comfortable to use while ensuring the high conductivity of the electrode, and can better detect electrophysiological signals. Background Art

[0002] Recently, the application of electromyography (EMG) monitoring technology has been significantly expanded in patient diagnosis, rehabilitation therapy, human-machine interface, and prosthetic control. However, traditional wet electrodes still have certain limitations in the application of electromyography recording. These limitations mainly come from their construction based on rigid metal and conductive gel, which not only leads to signal quality degradation and motion artifacts, but also may cause skin allergies and other problems.

[0003] In the current market, flexible EMG electrode patches face many challenges in multiple key technical fields. For example, the biocompatibility of some flexible electrode materials has not yet reached the ideal standard, and long-term wearing may cause allergic reactions. At the same time, the contact conductivity between the electrode and the skin needs to be optimized to reduce signal attenuation and noise interference. In addition, the biocompatibility of the electrode patch also needs to be further enhanced to prevent problems such as shedding, displacement, or skin irritation and inflammation during use. In view of this, the research and development of flexible EMG electrode patches is still a challenging field but also has great development potential. Summary of the invention

[0004] The technical solution of the present invention is: in view of the shortcomings of the prior art, a flexible wearable liquid metal-based electrospinning flexible electrode patch and its preparation method and application are proposed, the electrode patch exhibits excellent conductivity and long working life characteristics, the method is simple, efficient and highly repeatable, and effectively overcomes the problem of the insufficiency of traditional electrodes in biocompatibility. The new flexible dry electrode is used for electromyography monitoring. The electrode is made by screen printing in conductive ink on an electrospinning material. This new electrode not only ensures comfort when worn, but also maintains high conductivity, so that electromyographic signals can be measured more accurately in daily activities and sports.

[0005] The technical solution of the present invention is:

[0006] A flexible wearable liquid metal-based electrospinning flexible electrode patch, the flexible wearable liquid metal-based electrospinning flexible electrode patch consisting of a flexible substrate and conductive ink;

[0007] The raw materials of the flexible substrate include polyacrylonitrile and N,N-dimethylformamide;

[0008] The raw materials of conductive ink include gelatin, liquid metal, water and nano silver wires;

[0009] Taking the total mass of the raw materials of the flexible substrate as 100%, the mass percentage of each component is:

[0010] Polyacrylonitrile 27%-33%

[0011] N,N-dimethylformamide 67%-73%

[0012] Taking the total mass of the raw materials of the conductive ink as 100%, the mass percentage of each component is:

[0013] Gelatin 6%-7%

[0014] Liquid Metal Gallium Indium Alloy 72%-76%

[0015] Water 17%-21%;

[0016] Nano silver wire 0.5%-1%.

[0017] The liquid metal is at least one of gallium, mercury, gallium-indium alloy, gallium-indium-tin alloy, bismuth-tin alloy, and bismuth-tin-lead-indium alloy.

[0018] The liquid metal is a gallium-indium alloy, in which the mass fraction of gallium is 75.5% and the mass fraction of indium is 24.5%.

[0019] A method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch comprises the following steps:

[0020] Step 1, mixing polyacrylonitrile and N,N-dimethylformamide to obtain a polyacrylonitrile solution;

[0021] Step 2, using the polyacrylonitrile solution obtained in step 1 to perform electrostatic spinning to obtain polyacrylonitrile fibers;

[0022] Step 3, mixing gelatin and water, stirring magnetically, adding liquid metal and nano silver wires and performing ultrasonic dispersion after the gelatin and water are fully dissolved, to obtain conductive ink;

[0023] Step 4, laying the polyacrylonitrile fiber obtained in step 2 on the lower surface of the screen printing screen;

[0024] Step 5, drop the conductive ink obtained in step 3 on the upper surface of the screen printing screen obtained in step 4, and print the conductive ink on the polyacrylonitrile fiber located on the lower surface of the screen printing screen by scraping with a scraper to obtain a flexible wearable liquid metal-based electrospinning flexible electrode patch.

[0025] In the step 1, the temperature when polyacrylonitrile and N,N-dimethylformamide are mixed is 85-95° C., magnetic stirring is performed during the mixing, the magnetic stirring speed is 400-600 r / min, and the mixing time is 12-24 h.

[0026] In the step 2, the electrospinning parameters are: needle model 21G, discharge speed 0.1-0.2 mL / h, spinning voltage 17-20 KV, and receiving distance 10-12 cm.

[0027] In step 3, the mixing time is 10-15 min, the temperature is 40-50° C., the magnetic stirring speed is 400-600 r / min; the power during ultrasonic dispersion is 200-400 W, and the ultrasonic dispersion time is 1-2 min.

[0028] In step 4, the screen printing screen is made by hand-carving a paint film or photochemical plate making, the screen printing screen mesh number is 100-200 mesh, the screen printing screen pattern line width range is 0.5-1mm, and the line spacing range is 1-2mm.

[0029] A flexible wearable liquid metal-based electrospun flexible electrode patch is applied. The flexible wearable liquid metal-based electrospun flexible electrode patch is attached to the arm as a sensor to measure electromyographic signals during daily life and exercise.

[0030] Due to the adoption of the above technical solution, the beneficial effects achieved by the present invention are:

[0031] (1) The present invention uses a gelatin polymer material with temperature-sensitive properties. By presenting a low-viscosity solution state under a high-temperature environment, it can be better dispersed in the solution with liquid metal gallium-indium alloy droplets and silver nanowires to form liquid metal / silver nanowire gelatin nanoparticles. This unique material combination not only improves the flexibility and fit of the electrode patch, but also after cooling to room temperature, the gelatin polymer material will solidify, thereby stably fixing the liquid metal and silver nanowires in the patch. In addition, based on the erasable and activated conductive properties, the flexible patch electrode can be stored for a long time without worrying about the oxidation of the liquid metal, and the circuit can also be selectively activated to provide personalized choices.

[0032] (2) The present invention introduces liquid metal gallium-indium alloy and nano silver wire as conductive reinforcing composite fillers. The liquid metal can be well filled into the pores of the one-dimensional linear material silver nanowire to realize an island-bridge interconnection structure. This composite material not only improves the conductive performance of the electrode patch, but also maintains stable electrical properties under mechanical stress such as bending and stretching.

[0033] (3) The present invention uses electrospinning as a substrate, which not only improves the flexibility and wearing comfort of the electrode patch, but also enhances its fit to the skin, thereby ensuring stable contact between the electrode and the skin during exercise. It has good durability, mechanical strength, biocompatibility, and biodegradability. In addition, electrospinning has a large specific surface area and a light texture, which can make the wearer more comfortable and meet the needs of long-term use.

[0034] (4) The present invention further proposes a collection unit of conductive electrodes printed on a flexible device, which is used as a carrier for collecting electromyographic signals, realizing a flexible, low-cost, and multifunctional electrospinning flexible electrode technology. This technology can not only be used for synchronous monitoring of physiological signals during exercise and daily life, but also exhibits high signal-to-noise ratio, signal accuracy, and lower impedance and skin interface impedance in signal collection.

[0035] In addition, the preparation method of the present invention is simple and suitable for large-scale production and popularization and application.

[0036] The present invention innovatively combines screen printing technology with electrospinning technology to develop a flexible wearable electrospinning electrode patch with low cost and excellent conductive performance. Its materials include gelatin, liquid metal gallium indium alloy, water, polyacrylonitrile, N,N-dimethylformamide and nano silver wire.

[0037] In the specific implementation process, polyacrylonitrile was first dissolved in N,N-dimethylformamide solution, and a flexible substrate was prepared using electrospinning technology, based on which the electrode patch structure was constructed. At the same time, liquid metal gallium indium alloy and nano silver wires, as key conductive components, were converted into ink with excellent conductive properties after ultrasonic dispersion treatment and evenly coated on the electrospinning substrate, and finally a flexible electrode patch with excellent conductive properties and extremely low skin contact impedance was successfully prepared.

[0038] It is worth mentioning that the present invention has made a breakthrough in printing the collection unit of the conductive electrode directly on the surface of the flexible device, making it an ideal choice for collecting electromyographic signals. This technology not only has the advantages of excellent flexibility, low cost, and comprehensive functions, which perfectly meets the needs of real-time synchronous monitoring of physiological signals in daily life and sports scenes, but also has a simple and smooth preparation process, which is easy to achieve large-scale mass production, showing a broad prospect for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the process of preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch of the present invention;

[0040] Figure 2This is a photo of a flexible wearable liquid metal-based electrospinning flexible electrode patch prepared by the preparation method of the present invention, wherein Figure 2 a is a photo of the object without scraping. Figure 2 b is a photo of the object after scraping and coating;

[0041] Figure 3 This is an electron microscope microscopic structure photo of a flexible wearable liquid metal-based electrospinning flexible electrode patch prepared by the preparation method of the present invention;

[0042] Figure 4 It is a histogram of the conductivity of the flexible electrode patch prepared by the preparation method of the present invention under different liquid metal contents;

[0043] Figure 5 The flexible electrode patch prepared by the preparation method of the present invention collects the EEG signal spectrum during blinking;

[0044] Figure 6 The electrocardiogram collected by the flexible electrode patch prepared by the preparation method of the present invention;

[0045] Figure 7 The electromyogram is collected by the flexible electrode patch prepared by the preparation method of the present invention;

[0046] Figure 8 It is a comparison chart of the signal-to-noise ratio data of the flexible electrode patch prepared by the preparation method of the present invention and the commercial electrode at 1 day, 3 days and 7 days. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0048] A flexible wearable liquid metal-based electrospinning flexible electrode patch is a printed patch composed of a flexible substrate and a conductive ink; the raw materials of the flexible substrate part include polyacrylonitrile (30wt%) and N,N-dimethylformamide (70wt%), and the conductive ink part includes gelatin (6wt%), liquid metal gallium indium alloy (74wt%), water (19wt%) and nano silver wires (1wt%), gelatin is used as a surfactant to disperse the liquid metal, and the liquid metal and nano silver wires are used to reduce material impedance, enhance conductivity and provide conductive properties.

[0049] A method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch comprises the following steps:

[0050] Step 1, preparing electrospinning polyacrylonitrile solution.

[0051] Step 2, electrostatically spinning the polyacrylonitrile solution to obtain polyacrylonitrile fibers.

[0052] Step 3, preparing the conductive ink, specifically, mixing gelatin with water, stirring with a magnetic force, adding liquid metal and nano silver wires and performing ultrasonic dispersion after the gelatin is fully dissolved, to obtain the conductive ink;

[0053] Step 4, dropping the conductive ink obtained in step 3 onto the surface of the screen printing screen, and printing the conductive ink on paper by scraping with a scraper to prepare a paper-based conductive electrode patch, thereby obtaining a flexible wearable liquid metal-based electrospinning flexible electrode patch;

[0054] In the step 1, the polyacrylonitrile solution is prepared by uniformly mixing polyacrylonitrile and N,N-dimethylformamide in a ratio of 3:7, dissolving at a temperature of 90° C. and with magnetic stirring at 500 r / min for 24 hours.

[0055] In the step 2, the electrospinning parameters are: needle model 21G, discharge speed 0.1 ml / h, spinning voltage 20 KV, and receiving distance 10-12 cm.

[0056] In the step 3, the mixing time is 10 minutes, the temperature is 45° C., and the magnetic stirring is 500 r / min; the power during ultrasonic dispersion is 200-400 W, and the ultrasonic dispersion time is 1 minute; the liquid metal is at least one of gallium, mercury, gallium-indium alloy, gallium-indium-tin alloy, bismuth-tin alloy, and bismuth-tin-lead-indium alloy; the liquid metal is gallium-indium alloy, and the mass fraction of gallium in the gallium-indium alloy is 75.5%, and the mass fraction of indium is 24.5%;

[0057] In step 4, the screen printing screen is made by hand-carving a paint film or photochemical plate making method, the screen printing screen mesh number is 100-200 mesh, the screen printing screen pattern line width range is 0.5-1mm, and the line spacing range is 12mm; the screen printing screen substrate is any one of paper materials such as tipping paper, cardboard, newsprint, writing paper, and electrospinning

[0058] Application of a flexible wearable liquid metal-based electrospun flexible electrode patch: The flexible wearable liquid metal-based electrospun flexible electrode patch developed in this study is attached to the surface of the arm as an epidermal sensor. It can accurately measure the electromyographic signals during daily activities and physical exercise. In addition, the device can also achieve long-term stable and high-precision signal acquisition.

[0059] The prepared flexible wearable liquid metal-based electrospinning flexible electrode patch is attached to the surface of the arm as a sensor, and is attached to three equally spaced positions on the arm. The three electrode patches are connected to the connector through wires to measure multi-site electromyographic signals on the arm, and can achieve long-term undisturbed high-precision signal acquisition.

[0060] like Figure 1 As shown, a method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch comprises the following steps:

[0061] Step 1, preparing an electrospinning polyacrylonitrile solution, specifically, mixing polyacrylonitrile and N,N-dimethylformamide evenly, heating and magnetically stirring.

[0062] Step 2, electrostatically spinning the polyacrylonitrile solution to obtain polyacrylonitrile fibers.

[0063] Step 3, preparing a conductive printing ink solution, specifically comprising: mixing the silver nanowires and the liquid metal in a gelatin solvent, and performing ultrasonic dispersion during the mixing to obtain a liquid metal conductive ink;

[0064] Step 4, drop a small amount of liquid metal conductive ink from step 2 onto the surface of the screen template, and use a scraper to reciprocate and apply the ink to evenly print on the electrospinning surface to obtain a flexible, wearable liquid metal-based electrospinning flexible electrode patch.

[0065] Example 1

[0066] A method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch specifically comprises the following steps:

[0067] Step 1: Weigh 3 g of polyacrylonitrile and add it to 7 g of N,N-dimethylformamide solvent, then heat to 90°C and stir magnetically at 500 r / min for 24 h to completely dissolve it.

[0068] Step 2: Place the polyacrylonitrile solution in an electrospinning device, use a 21G needle and control the electrospinning speed to 0.1 ml / h, the voltage to 20 kV, and spin to obtain polyacrylonitrile electrospun nanofibers.

[0069] Step 3: Weigh 1g of gelatin and dissolve it in 4g of water. Stir it for 10min in a magnetic stirring at 45°C. The magnetic stirring speed is fixed at 500r / min. After it is completely dissolved, take 1g of the solution, add 3g (74wt%) of liquid metal gallium-indium alloy and 0.03g of nano silver wire, and use a cell disruptor with an ultrasonic power of 120w to ultrasonicate for 1min to completely dissolve it to obtain liquid metal conductive ink; the mass fraction of gallium in the gallium-indium alloy is 75.5%, and the mass fraction of indium is 24.5%;

[0070] Step 4: Add conductive ink to one side of the polyurethane screen, place polyacrylonitrile electrospinning under the screen, and scrape the screen surface back and forth at a constant speed with a handheld scraper at a 45° angle to obtain a flexible wearable liquid metal-based electrospinning flexible electrode patch, which is named LM-3g electrode patch.

[0071] Example 2

[0072] The difference from Example 1 is that the mass of the liquid metal gallium-indium alloy added in step 3 is 2 g (66 wt %), and the obtained product is named LM-2g electrode patch.

[0073] Example 3

[0074] The difference from Example 1 is that the mass of the liquid metal gallium-indium alloy added in step 3 is 4 g (80 wt %), and the obtained product is named LM-4g electrode patch.

[0075] Comparative Example 1

[0076] The difference from Example 1 is that the electrode sheet used is the Cardinal H135S ECG electrode sheet.

[0077] Figure 2 This is a photo of the LM-3g electrode patch in Example 1. Figure 2 It can be seen that the size of the LM-3g electrode patch is 6*5cm 2 , thickness is 1mm, Figure A is a real picture of the liquid metal passageway connected after scraping off the surface gelatin. Figure B is a real picture without scraping process.

[0078] Figure 3 The scanning electron microscope (SEM) image of the LM-3g electrode patch obtained in Example 1 of the present invention is shown, with a scale of 1 μm. It can be seen from the figure that the electrode pattern printed by screen printing is very accurate and clear lines can be seen.

[0079] Figure 4 The electrical conductivities of LM-3g, LM-2g, and LM-4g obtained in Examples 1, 2, and 3 of the present invention are compared. It can be seen from the figure that as the liquid metal content increases, the electrical conductivity continues to increase, and the electrical conductivity of Example 1 is better than that of Example 2. However, too much liquid metal will lead to poor dispersion performance, resulting in poor connection performance of the printed pattern and decreased conductivity.

[0080] When the product obtained in Example 1 is connected to an EEG signal acquisition device for monitoring, Figure 5 As shown in the figure, the EEG signal during the blinking process can be clearly observed, and the signal waveform is clear without obvious interference. These data clearly reflect the changes in the EEG signal during the blinking action.

[0081] When the product obtained in Example 1 is connected to an ECG signal acquisition device for monitoring, Figure 6 As shown in the figure, the ECG signal related to the heartbeat can be clearly observed, and the signal waveform is clear without obvious interference. These data clearly reflect the changes in ECG signals in daily life.

[0082] When the product obtained in Example 1 is connected to the electromyographic signal acquisition device for monitoring, as shown in FIG. Figure 7 As shown in the figure, the electromyographic signals of the arm during the process of clenching and releasing the fist can be clearly observed. In addition, the electrode patch shows good stability and durability during long-term use. Figure 8 As shown, by comparing the myoelectric noise ratio data of the electrode patch obtained in Example 1 and the comparative example after being placed for 1 day, 3 days, and 7 days, it can be seen that the electrospinning flexible electrode patch has a higher signal-to-noise ratio value than the commercial electrode. In addition, due to the loss of water in the commercial electrode during long-term placement, the electrode performance dropped sharply, and it could not work normally on the third day, and the signal-to-noise ratio data could not be measured.

[0083] In summary, the present invention provides a flexible wearable liquid metal-based electrospinning flexible electrode patch. The electrode patch can stably collect signals, ensure high-quality electromyographic recordings, and have a good signal-to-noise ratio, thereby providing reliable protection for the electromyographic signal acquisition system. Through the preparation method adopted by the present invention, the obtained flexible electrode patch has high conductivity and good biocompatibility, while maintaining excellent signal acquisition performance, and can match the common electromyographic signal acquisition equipment on the market.

[0084] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A flexible wearable liquid metal-based electrospinning flexible electrode patch, characterized in that: The flexible wearable liquid metal-based electrospinning flexible electrode patch consists of a flexible substrate and conductive ink; The raw materials of the flexible substrate include polyacrylonitrile and N,N-dimethylformamide; The raw materials of conductive ink include gelatin, liquid metal, water and nano silver wires; Taking the total mass of the raw materials of the flexible substrate as 100%, the mass percentage of each component is: Polyacrylonitrile 27%-33% N,N-dimethylformamide 67%-73% Taking the total mass of the raw materials of the conductive ink as 100%, the mass percentage of each component is: Gelatin 6%-7% Liquid Metal Gallium Indium Alloy 72%-76% Water 17%-21%; Nano silver wire 0.5%-1%.

2. A flexible wearable liquid metal-based electrospinning flexible electrode patch according to claim 1, characterized in that: The liquid metal is at least one of gallium, mercury, gallium-indium alloy, gallium-indium-tin alloy, bismuth-tin alloy, and bismuth-tin-lead-indium alloy.

3. A flexible wearable liquid metal-based electrospinning flexible electrode patch according to claim 1, characterized in that: The liquid metal is a gallium-indium alloy, in which the mass fraction of gallium is 75.5% and the mass fraction of indium is 24.5%.

4. A method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch, characterized in that The following steps are involved: Step 1, mixing polyacrylonitrile and N,N-dimethylformamide to obtain a polyacrylonitrile solution; Step 2, using the polyacrylonitrile solution obtained in step 1 to perform electrostatic spinning to obtain polyacrylonitrile fibers; Step 3, mixing gelatin and water, stirring magnetically, adding liquid metal and nano silver wires and performing ultrasonic dispersion after the gelatin and water are fully dissolved, to obtain conductive ink; Step 4, laying the polyacrylonitrile fiber obtained in step 2 on the lower surface of the screen printing screen; Step 5, drop the conductive ink obtained in step 3 on the upper surface of the screen printing screen obtained in step 4, and print the conductive ink on the polyacrylonitrile fiber located on the lower surface of the screen printing screen by scraping with a scraper to obtain a flexible wearable liquid metal-based electrospinning flexible electrode patch.

5. The method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch according to claim 1, characterized in that: In the step 1, the temperature when polyacrylonitrile and N,N-dimethylformamide are mixed is 85-95° C., magnetic stirring is performed during the mixing, the magnetic stirring speed is 400-600 r / min, and the mixing time is 12-24 h.

6. The method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch according to claim 1, characterized in that: In the step 2, the electrospinning parameters are: needle model 21G, discharge speed 0.1-0.2 mL / h, spinning voltage 17-20 KV, and receiving distance 10-12 cm.

7. The method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch according to claim 1, characterized in that: In step 3, the mixing time is 10-15 min, the temperature is 40-50° C., the magnetic stirring speed is 400-600 r / min; the power during ultrasonic dispersion is 200-400 W, and the ultrasonic dispersion time is 1-2 min.

8. The method for preparing a flexible wearable liquid metal-based electrospinning flexible electrode patch according to claim 1, characterized in that: In step 4, the screen printing screen is made by hand-carving a paint film or photochemical plate making, the screen printing screen mesh number is 100-200 mesh, the screen printing screen pattern line width range is 0.5-1mm, and the line spacing range is 1-2mm.

9. Application of a flexible wearable liquid metal-based electrospinning flexible electrode patch, characterized in that: The flexible wearable liquid metal-based electrospinning flexible electrode patch prepared by any method of claims 4-8 is used as a sensor to measure electromyographic signals.

10. The application of a flexible wearable liquid metal-based electrospinning flexible electrode patch according to claim 9, characterized in that: A flexible and wearable liquid metal-based electrospun flexible electrode patch is attached to the arm as a sensor to measure electromyographic signals during daily life and exercise.

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