Flexible patch dry electrode and method of making the same

Abstract

The application discloses a preparation method of a flexible patch dry electrode, and comprises the following steps: uniformly mixing polydimethylsiloxane (PDMS) and carbon material, ultrasonicating, spin coating on a substrate to obtain an electrode, punching the electrode after drying, injecting conductive silver paste into the hole, and obtaining the flexible patch dry electrode after baking and curing, wherein the carbon material accounts for 4-8 wt% of the total mass of the carbon material and the polydimethylsiloxane, and the carbon material is a mixture of graphene oxide (GO) and carbon nanotubes (CNT). The polydimethylsiloxane is used as a flexible substrate material, the prepared flexible patch dry electrode has good flexibility and does not cause discomfort to the subjects; the conductive network constructed by the carbon material is combined with the conductive silver paste, and the conductive signal transmission capacity of the flexible patch dry electrode is strengthened; the preparation method of the flexible patch dry electrode is simple, convenient to operate and low in cost, cross infection between the subjects is avoided, and the flexible patch dry electrode is safe and comfortable.

Description

Technical Field

[0001] This invention belongs to the field of flexible patch dry electrode technology, specifically relating to a flexible patch dry electrode and its preparation method. Background Technology

[0002] The brain is one of the most vital organs in the human body, generating a vast amount of electrical signals to control various organs and possessing highly complex functions. In current human brain research experiments, monitoring electroencephalogram (EEG) signals is one of the most widely used monitoring methods. EEG signals are electrical signals formed by changes in electrical potential generated by neural activity in the brain, accurately reflecting various physiological activities within the brain and containing a wealth of information about brain activity. Therefore, EEG signals have become an important tool for studying brain science, cognitive science, human-computer interaction, and the clinical diagnosis of brain diseases, making the acquisition of EEG signals a crucial step.

[0003] Electroencephalography (EEG) is currently used for physiological information monitoring, neurofeedback training, auxiliary diagnosis and treatment of neurological and brain-related diseases, research on brain cognitive function, and the recently popular field of brain-computer interfaces (BCI). Recent medical research data shows that brain-related diseases remain a significant threat to human life. This has led to increased research focus on the human brain, and given the current situation, acquiring effective EEG signals and analyzing their characteristics and patterns has become a pressing task for researchers. Acquiring reliable and effective EEG signals requires a stable, low-impedance, comfortable, and easy-to-operate EEG electrode. Therefore, designing reliable and comfortable EEG electrodes is a major challenge for researchers. Current EEG acquisition techniques include invasive and non-invasive methods, with mainstream EEG research primarily based on non-invasive methods. In non-invasive EEG acquisition, the commonly used Ag / AgCl wet electrode is the gold standard for recording EEG signals. However, the use of conductive gel and the cumbersome operation of wet electrodes during EEG acquisition severely limit their widespread application in research. Another method, dry electrodes, does not require conductive gel or skin preparation. While dry electrodes offer rapid installation and a significantly improved user experience, they still have some limitations (relatively poor invasiveness and sensitivity to motion artifacts), restricting their performance in practical applications. Currently, researchers both domestically and internationally have made many different attempts in the research of flexible dry electrodes. For example, Zhu et al. designed and fabricated a flexible graphene fabric electrode that can be worn for extended periods and reused repeatedly in 2020. Using graphite as the raw material, conductive graphene was prepared using a redox method, and the graphene was then attached to a flexible polyester fiber (fabric) substrate using a vacuum filtration method to create a flexible graphene electrode. Adhesive was added to increase the adhesion of the graphene and improve its anti-friction properties. Because the electrode itself is a dry electrode, it does not suffer from the signal attenuation problem that occurs with traditional wet electrodes over time, making it suitable for long-term continuous EEG monitoring. To investigate the sensitivity of graphene flexible electrodes for EEG signal detection, a 1 cm diameter graphene electrode sheet was fixed to the forehead of a 24-year-old healthy male subject using an elastic EEG cap and connected to an EEG system via a fixed-length cable. Commercially available silver chloride electrodes were used as a reference electrode and a ground electrode for comparison. Results showed that the waveforms acquired by the graphene electrode and the silver chloride electrode were essentially identical without distortion, with similar signal amplitudes and noise levels. Their signal-to-noise ratios were 25.8 dB and 26.2 dB, respectively, indicating that the graphene electrode could obtain EEG signals with an ideal signal-to-noise ratio. While the signal acquisition performance of this graphene fabric electrode basically meets daily acquisition needs, its manufacturing process is complex and costly, hindering widespread adoption.

[0004] In 2018, Chen et al. designed and fabricated a flexible forehead EEG dry electrode. This dry electrode was made by doping a rubber substrate with conductive silver powder, and its contact surface with the scalp was designed as an arc-shaped surface. Compared to planar electrodes, this electrode has the advantages of closer contact with the scalp, a larger skin contact area, and less slippage on the skin. Skin contact impedance measurements of the dry and wet electrodes at the forehead were compared; at 10Hz, the contact impedances were 26.5±16.2kΩ and 12.8±5.7kΩ, respectively. In the EEG acquisition comparison experiment, the average correlation coefficient between the dry and wet electrodes was 0.95; in the alpha rhythm test experiment, both showed typical alpha rhythm peaks. However, due to individual differences, the degree of adhesion between the electrode substrate can vary and cannot be guaranteed at all times, thus affecting the impedance between the electrode and the scalp and leading to performance degradation.

[0005] In 2016, Qin et al. designed and fabricated an Ag / AgCl EEG electrode based on a flexible polyimide (PI) substrate using screen printing technology. The results showed that the flexible electrode had a porous surface and good adhesion to the substrate. The electrode exhibited the electrochemical interface properties of Ag / AgCl, with an equilibrium potential of 0.97 ± 0.20 mV, similar to that of Ag / AgCl powder electrodes. Furthermore, the electrode potential showed good consistency and stability, with a maximum potential difference not exceeding 0.7 mV, and a potential drift value within 10 μV / 4 min after 4 hours. After treatment with GT5 conductive paste, the electrode-skin impedance was within 5 kΩ, meeting the requirements for EEG recording. Compared to the high impedance of human skin, the interfacial impedance of the flexible electrode-conductive paste (GT20) was only 166 Ω·cm². Electrode potential stability directly affects the baseline stability and signal-noise ratio of EEG recordings. The electrode potential stability over time shows a decreasing trend in equilibrium potential, becoming increasingly closer to the electrode potential of the powdered Ag / AgCl reference electrode. The electrode potential drift also gradually decreases over time, stabilizing after 4 hours. After 1 hour, the equilibrium potential of the electrode within a 4-minute timeframe was 0.966±0.200 mV, with the largest drift value of 48.8±16.0 μV; after 7 hours, the equilibrium potential was 0.357±0.117 mV, with the smallest drift value of 6.7±4.8 μV. This indicates that the flexible electrode has a very stable electrode potential, which is beneficial for maintaining a stable baseline in EEG recordings and reducing signal noise. It should also be noted that the electrode potential drift values ​​at 4 hours and 7 hours did not exceed 10 μV, indicating that the flexible electrode can stably record EEG signals for extended periods. Although the electrode performance is stable, it requires the use of abrasive paste and conductive paste, making its operation complex and cumbersome during use. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a flexible patch dry electrode. This method utilizes polydimethylsiloxane (PDMS) as a flexible substrate material, adding graphene oxide (GO) and carbon nanotubes (CNTs), followed by mixing and stirring. Ultrasonication is then used to uniformly disperse the dopants throughout the flexible substrate material. The mixture is then spin-coated onto a polished copper foil, solidified, and finally perforated and injected with conductive silver paste. The flexible patch dry electrode prepared by this method uses copper foil as a substrate, constructs an electrical grid using carbon nanotubes, utilizes graphene oxide to reduce polarization potential while increasing affinity with the scalp, and utilizes conductive silver paste to further enhance the electrode's conductivity. This method combines the advantages of both wet and dry electrodes while overcoming their respective disadvantages.

[0007] Another object of the present invention is to provide a flexible patch dry electrode obtained by the above preparation method.

[0008] The objective of this invention is achieved through the following technical solution.

[0009] A method for fabricating a flexible patch dry electrode includes the following steps:

[0010] Polydimethylsiloxane (PDMS) and carbon material are mixed evenly, ultrasonically, and spin-coated onto a substrate to obtain an electrode. After the electrode is dried, holes are drilled, conductive silver paste is injected into the holes, and the electrode is baked and cured to obtain the flexible patch dry electrode. The carbon material accounts for 4-8 wt% of the total mass of carbon material and PDMS. The carbon material is a mixture of graphene oxide (GO) and carbon nanotubes (CNTs). By mass fraction, the ratio of graphene oxide (GO) to carbon nanotubes (CNTs) is (1-5):1.

[0011] In the above technical solution, the substrate is copper foil. Before spin coating, the side of the copper foil to be spin coated is first polished and then cleaned. The dimensions of the copper foil are: length 18-18.2mm and width 14.5-15.5mm.

[0012] In the above technical solution, the polydimethylsiloxane (PDMS) is obtained by mixing a silicone elastomer substrate and a silicone elastomer curing agent, wherein the ratio of the silicone elastomer substrate to the silicone elastomer curing agent by mass parts is 10:1.

[0013] In the above technical solution, the ultrasound duration is 5 to 10 minutes.

[0014] In the above technical solution, the spin coating operation is repeated at least twice to make the thickness of the electrode 0.2 to 0.25 mm. After each spin coating, the electrode is dried and solidified for 10 to 15 minutes after each drying.

[0015] In the above technical solution, the spin coating is performed by first performing low-speed spin coating and then high-speed spin coating. The rotation speed of the low-speed spin coating is 400-600 rpm / min, the rotation speed of the high-speed spin coating is 1000-1200 rpm / min, the low-speed spin coating time is 6-10s, and the high-speed spin coating time is 10-15s.

[0016] In the above technical solution, the thickness of the substrate is 0.08 to 0.12 mm.

[0017] In the above technical solution, the drying temperature is 60-70℃ and the drying time is 10-15 minutes.

[0018] In the above technical solution, there are 19 holes, each with a diameter of 0.45 mm, and the 19 holes are arranged in a hexagonal pattern.

[0019] In the above technical solution, the baking temperature is 60-70℃ and the baking time is 10-20 minutes.

[0020] The flexible patch dry electrode obtained by the above preparation method.

[0021] This invention uses polydimethylsiloxane as a flexible substrate material, and the prepared flexible patch dry electrode has excellent flexibility and will not cause discomfort to the subject. The conductive mesh constructed by carbon material combined with conductive silver paste enhances the ability of the flexible patch dry electrode to conduct electrical signals. The preparation method of the flexible patch dry electrode is simple, easy to operate, and inexpensive, avoiding cross-infection between subjects and ensuring safety and comfort. Attached Figure Description

[0022] Figure 1 The shape and dimensions of the substrate of this invention;

[0023] Figure 2 This is a schematic diagram of the overall structure of the flexible patch dry electrode prepared in Embodiment 1 of the present invention;

[0024] Figure 3 SEM (5000x magnification) of the flexible patch dry electrode prepared in Example 1 of this invention;

[0025] Figure 4 SEM (20000x magnification) of the flexible patch dry electrode prepared in Example 1 of this invention;

[0026] Figure 5 The frontal impedance (Fp1 channel) of the flexible patch dry electrode prepared in Example 1 of the present invention and the frontal impedance (F7 channel) of the traditional Ag / AgCl wet electrode are shown.

[0027] Figure 6The blink time-domain waveforms (F7 channel) of the flexible patch dry electrode (Fp1 channel) prepared in Example 1 of the present invention and the traditional Ag / AgCl wet electrode are shown.

[0028] Figure 7 The time-domain waveforms of the flexible patch dry electrode (Fp1 channel) prepared in Example 1 of the present invention and the traditional Ag / AgCl wet electrode (F7 channel) are shown in the biting time domain.

[0029] Figure 8 The blink correlation coefficient between the flexible patch dry electrode prepared in Example 1 of this invention and the traditional Ag / AgCl wet electrode;

[0030] Figure 9 The correlation coefficient between the flexible patch dry electrode prepared in Example 1 of this invention and the traditional Ag / AgCl wet electrode for teeth biting;

[0031] Figure 10 The pillow region experimental impedance of the flexible patch dry electrode (Oz position) and the conventional Ag / AgCl wet electrode (Pz position) prepared in Example 1 of the present invention;

[0032] Figure 11 The pillow region time-domain waveforms of the flexible patch dry electrode (Oz position) and the conventional Ag / AgCl wet electrode (Pz position) prepared in Example 1 of the present invention;

[0033] Figure 12 The correlation coefficient of the pillow region between the flexible patch dry electrode prepared in Example 1 of this invention and the traditional Ag / AgCl wet electrode;

[0034] Figure 13 The frequency domain waveform of the pillow region test of the α wave is shown, where a is a traditional Ag / AgCl wet electrode and b is a flexible patch dry electrode prepared in Example 1 of the present invention.

[0035] Figure 14 This refers to the forehead test electrode area of ​​the flexible patch dry electrode prepared in Embodiment 1 of the present invention;

[0036] Figure 15 This refers to the flexible patch dry electrode pillow region test electrode region prepared in Embodiment 1 of the present invention;

[0037] Figure 16 The curves are in the frequency domain. The solid line represents the frequency domain curve when the eyes are closed, and the dashed line represents the frequency domain curve when the eyes are open. In this context, A is the flexible patch dry electrode prepared in Example 1, and B is the flexible patch dry electrode (GO-CNT) prepared in Comparative Example 1. Detailed Implementation

[0038] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0039] The relevant instruments and equipment used in the specific embodiments of this invention are as follows:

[0040] KW-4A Spin Coating Machine: Institute of Microelectronics, Chinese Academy of Sciences;

[0041] GraelEEG equipment: Beijing Qingjing Electronic Technology Co., Ltd., Grael model 32-lead EEG acquisition equipment;

[0042] Conductive silver paste: Shenzhen Wovis Electronic Technology Co., Ltd.;

[0043] Silicone elastomer substrate: Trademark of The Dow Chemical Company;

[0044] Silicone elastomer curing agent: Trademark of The Dow Chemical Company;

[0045] Traditional Ag / AgCl wet electrode: manufactured by Beijing Qingjing Electronic Technology Co., Ltd.

[0046] Example 1

[0047] A method for fabricating a flexible patch dry electrode includes the following steps:

[0048] In a beaker, add polydimethylsiloxane (PDMS) and carbon material, and stir evenly with a glass rod. Seal the beaker and place it in an ultrasonic device for 8 minutes to sonicate, allowing the carbon material to be evenly distributed in the PDMS, resulting in a colloid mixture. Prepare a copper foil with a thickness of 0.1 mm as a substrate, and cut the substrate into a flat teardrop shape with a length of 18.1 mm and a width of 15 mm, as shown. Figure 1 As shown, the side of the cut copper foil to be coated is sanded with fine sandpaper and then washed with ultrapure water.

[0049] Spin coating: Connect the KW-4A spin coater to the vacuum pump, turn on the power, turn on the spin coater's main switch, and turn on the vacuum pump switch to evacuate air. Place the cleaned copper foil on the spin coater's stage and press the suction button on the spin coater to adhere the copper foil to the stage. On the spin coater's operating interface, set the speed to low 600 rpm / min for 6 seconds and high 1200 rpm / min for 10 seconds. Use a glass rod to apply the mixture to the copper foil on the stage, press the spin coater's start button, and spin coat the mixture onto the copper foil to obtain the electrode. After the spin coater stops running, lift the suction button and remove the electrode with tweezers.

[0050] The electrode was dried under an infrared lamp at 70°C for 8 minutes until the electrode surface was dry, and then left at room temperature for 15 minutes to solidify.

[0051] Repeat the spin coating process once.

[0052] Dry the electrodes at 70℃ under an infrared lamp for 15 minutes until they are completely dry. Then, drill 19 holes (0.45 mm in diameter) into the fully dried electrodes. The 19 holes are arranged in a hexagonal pattern (from top to bottom: 3 holes, 4 holes, 5 holes, 4 holes, 3 holes, with equal spacing between holes). Figure 2 As shown, conductive silver paste is injected into the holes and baked at 70°C for 15 minutes under an infrared lamp to cure the conductive silver paste, thus obtaining a flexible patch dry electrode. In this electrode, polydimethylsiloxane (PDMS) is a mixture of silicone elastomer substrate and silicone elastomer curing agent. The carbon material accounts for 4 wt% of the total mass of carbon material and PDMS. The carbon material is a mixture of graphene oxide (GO) and carbon nanotubes (CNTs). By mass, the ratio of graphene oxide (GO) to carbon nanotubes (CNTs) is 1:1, and the ratio of silicone elastomer substrate to silicone elastomer curing agent is 10:1.

[0053] Comparative Example 1

[0054] A method for preparing a flexible patch dry electrode (GO-CNT), compared with Example 1, eliminates the step of adding conductive silver paste, and specifically includes the following steps:

[0055] In a beaker, add polydimethylsiloxane (PDMS) and carbon material, and stir evenly with a glass rod. Seal the beaker and place it in an ultrasonic device for 8 minutes to sonicate, allowing the carbon material to be evenly distributed in the PDMS, resulting in a colloid mixture. Prepare a copper foil with a thickness of 0.1 mm as a substrate, and cut the substrate into a flat teardrop shape with a length of 18.1 mm and a width of 15 mm, as shown. Figure 1 As shown, the side of the cut copper foil to be coated is sanded with fine sandpaper and then washed with ultrapure water.

[0056] Spin coating: Connect the KW-4A spin coater to the vacuum pump, turn on the power, turn on the spin coater's main switch, and turn on the vacuum pump switch to evacuate air. Place the cleaned copper foil on the spin coater's stage and press the suction button on the spin coater to adhere the copper foil to the stage. On the spin coater's operating interface, set the speed to low 600 rpm / min for 6 seconds and high 1200 rpm / min for 10 seconds. Use a glass rod to apply the mixture to the copper foil on the stage, press the spin coater's start button, and spin coat the mixture onto the copper foil to obtain the electrode. After the spin coater stops running, lift the suction button and remove the electrode with tweezers.

[0057] The electrode was dried under an infrared lamp at 70°C for 8 minutes until the electrode surface was dry, and then left at room temperature for 15 minutes to solidify.

[0058] Repeat the spin coating process once.

[0059] Dry the electrodes at 70℃ under an infrared lamp for 15 minutes until they are completely dry. Then, drill 19 holes (0.45 mm in diameter) in a hexagonal arrangement on the fully dried electrodes. Figure 2 As shown, a flexible patch dry electrode (GO-CNT) is obtained, wherein polydimethylsiloxane (PDMS) is a mixture of silicone elastomer substrate and silicone elastomer curing agent, carbon material accounts for 4wt% of the total mass of carbon material and PDMS, and the carbon material is a mixture of graphene oxide (GO) and carbon nanotubes (CNTs). By mass, the ratio of graphene oxide (GO) to carbon nanotubes (CNTs) is 1:1, and the ratio of silicone elastomer substrate to silicone elastomer curing agent is 10:1.

[0060] like Figure 3 , 4 As shown in the figure, the SEM of the flexible patch dry electrode prepared in Example 1 clearly shows the support relationship between the sheet structure of graphene and the tubular structure of carbon nanotubes and polydimethylsiloxane. That is, the sheet structure of graphene and the tubular structure of carbon nanotubes are uniformly distributed on polydimethylsiloxane.

[0061] Electroencephalogram (EEG) data collection was performed on the frontal (hairless area) using GraelEEG equipment and Curry8 software.

[0062] Specific procedures: Two conventional Ag / AgCl wet electrodes were used as ground and reference electrodes, respectively, and attached to the back of the subject's ears on both sides. A third conventional Ag / AgCl wet electrode and the flexible patch dry electrode prepared in Example 1 were attached to the subject's forehead at positions F7 and Fp1, respectively. Figure 14 As shown, the third conventional Ag / AgCl wet electrode and the flexible patch dry electrode prepared in Example 1 were both connected to the acquisition amplifier. A sampling rate of 4096 (4096 potential difference data points per second) was set to begin recording the signal and frontal impedance. The results are as follows: Figure 5 As shown, by Figure 5 It can be seen that the forward impedance of the flexible patch dry electrode is 27.6kΩ, while the forward impedance of the traditional Ag / AgCl wet electrode is 1.5kΩ.

[0063] During the recording process, participants blinked at 2s, 5s, and 8s, remaining focused at other times. The results are as follows: Figure 6 During the teeth-gripping test, the positions of the third conventional Ag / AgCl wet electrode and the flexible patch dry electrode prepared in Example 1 remained unchanged. Subjects clenched their teeth at positions of 2s, 5s, and 8s, respectively, for 1 second each, while remaining focused at other times. The results are as follows: Figure 7 As shown. By Figure 6 , 7It can be seen that there are obvious negative peaks in the graph when blinking and clenching teeth at the 2, 5, and 8-second intervals.

[0064] After the experiment was completed, in the data processing stage, the collected CDT files were converted into CNT files using the curry8 software to ensure that MATLAB could read the data correctly. After saving, MATLAB was opened for data processing, and correlation processing was performed on the time-domain data, such as... Figure 8 and Figure 9 As shown. By Figure 8 , 9 It can be seen that the correlation coefficient between the flexible patch dry electrode prepared in Example 1 and the traditional Ag / AgCl wet electrode for blinking is 94.8%, and the correlation coefficient between the flexible patch dry electrode prepared in Example 1 and the traditional Ag / AgCl wet electrode for teeth clenching is 90.9%. It can be seen that the correlation between the flexible patch dry electrode and the traditional Ag / AgCl wet electrode both reach more than 90%, indicating that the two have very similar performance and meet the requirements of EEG acquisition.

[0065] Electroencephalogram (EEG) data collection was performed on the occipital region (hair area) using GraelEEG equipment and Curry8 software.

[0066] Specific procedures: Two conventional Ag / AgCl wet electrodes were used as the ground and reference electrodes, respectively, and attached to the back of the subject's ears on both sides. A third conventional Ag / AgCl wet electrode and the flexible patch dry electrode prepared in Example 1 were attached to the Pz and Oz positions of the subject's occipital region, respectively. The flexible patch dry electrode prepared in Example 1 was placed at the Oz position, and the conventional Ag / AgCl wet electrode was placed at the Pz position. Figure 15 As shown, a sampling rate of 4096 was still used to begin recording the signal and the experimental impedance of the pillow region; the flexible patch dry electrode prepared in Example 1 was used to perform alpha wave testing on the subjects and compared with the traditional Ag / AgCl wet electrode. Figure 10 It can be seen that the impedance of the flexible patch dry electrode prepared in Example 1 is 18.7kΩ, while the impedance of the traditional Ag / AgCl wet electrode is 3.8kΩ, which meets the impedance requirements of the corresponding electrode types.

[0067] The subject was fully relaxed and prepared for the experiment, closing their eyes and calming their mind beforehand. The operator then pressed the recording button. After 5 seconds of closed eyes, the operator gave a signal to open the eyes, which the subject immediately did. Recording stopped after another 5 seconds. The subject remained still throughout the process, and the time-domain waveform of the pillow region was obtained. The results are as follows... Figure 11 As shown. By Figure 11 It can be seen that the first 5 seconds are the subject's closed eyes (before the vertical line in the figure), and the next 5 seconds are the subject's open eyes (after the vertical line in the figure).

[0068] After the experiment was completed, in the data processing stage, the collected CDT files were converted into CNT files using the curry8 software to ensure that MATLAB could read the data correctly. After saving, MATLAB was opened for data processing. First, the data was processed for correlation, such as... Figure 12 As shown. By Figure 12 It can be seen that the correlation coefficient between the flexible patch dry electrode prepared in Example 1 and the traditional Ag / AgCl wet electrode is 82.01%.

[0069] The time-domain data was transformed into frequency-domain data through a Fast Fourier Transform (FFT), thereby obtaining the pillow region test frequency-domain waveforms of the α-wave of the flexible patch dry electrode prepared in Example 1 and the traditional Ag / AgCl wet electrode, as shown below. Figure 13 As shown in the figure, a significant peak can be observed in the 8-13Hz range.

[0070] In summary, the flexible patch dry electrode prepared in Example 1 has the characteristics of flexibility compared with the traditional Ag / AgCl wet electrode, making the subjects feel more comfortable. The impedance is below 30KΩ, and the correlation coefficient with the traditional Ag / AgCl wet electrode reaches more than 80%.

[0071] Electroencephalogram (EEG) data collection was performed on the occipital region (hair area) using GraelEEG equipment and Curry8 software.

[0072] Specific procedures: A comparative EEG acquisition experiment was conducted on the radicular regions of the flexible patch dry electrode prepared in Example 1 and the flexible patch dry electrode (GO-CNT) prepared in Comparative Example 1. Alpha wave testing was performed on the subjects. The flexible patch dry electrode of Example 1 was positioned at the Oz position, and the flexible patch dry electrode (GO-CNT) of Comparative Example 1 was positioned at the Pz position. Two conventional Ag / AgCl wet electrodes were used as the ground and reference electrodes, respectively, and were attached to the sides behind the subjects' ears. The EEG acquisition process lasted a total of 10 seconds. The subjects closed their eyes for the first 5 seconds and opened them for the last 5 seconds. The recorded data was then exported as a cnt file and processed in the frequency domain using Matlab to obtain the frequency domain curve of the flexible patch dry electrode of Example 1, as shown below. Figure 16 As shown in Figure A, the frequency domain curve of the flexible patch dry electrode (GO-CNT) obtained in Comparative Example 1 is as follows: Figure 16 As shown in B.

[0073] Depend on Figure 16 It can be seen that, with the subjects' eyes closed, both exhibited peak values ​​in the 8-13Hz range, but the peak value of the flexible patch dry electrode with added conductive silver paste was more pronounced. Therefore, the performance of the flexible patch dry electrode in Example 1 is superior to that of the flexible patch dry electrode (GO-CNT) in Comparative Example 1.

[0074] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for fabricating a flexible patch dry electrode, characterized in that, Includes the following steps: Polydimethylsiloxane and carbon material are mixed evenly, ultrasonically, and spin-coated onto a substrate to obtain an electrode. After drying the electrode, holes are drilled, and conductive silver paste is injected into the holes. After baking and curing, the flexible patch dry electrode is obtained. The substrate is copper foil, and the carbon material accounts for 4-8 wt% of the total mass of carbon material and polydimethylsiloxane. The carbon material is a mixture of graphene oxide and carbon nanotubes, and the ratio of graphene oxide to carbon nanotubes by mass is (1-5):

1. The spin-coating operation is repeated at least twice, first at a low speed and then at a high speed. The rotation speed of the low-speed spin-coating is 400-600 rpm / min, and the rotation speed of the high-speed spin-coating is 1000-1200 rpm / min. The low-speed spin-coating time is 6-10 s, and the high-speed spin-coating time is 10-15 s. After each spin-coating, the electrode is dried, and after each drying, it solidifies for 10-15 min. The thickness of the electrode obtained after spin-coating is 0.2-0.25 mm.

2. The preparation method according to claim 1, characterized in that, Before spin coating, the side of the copper foil to be spin coated is first polished and then cleaned. The dimensions of the copper foil are: length 18~18.2mm and width 14.5~15.5mm.

3. The preparation method according to claim 2, characterized in that, The polydimethylsiloxane is obtained by mixing a silicone elastomer substrate and a silicone elastomer curing agent, wherein the ratio of the silicone elastomer substrate to the silicone elastomer curing agent by mass is 10:

1.

4. The preparation method according to claim 3, characterized in that, The ultrasound session lasted 5 to 10 minutes.

5. The preparation method according to claim 4, characterized in that, The thickness of the substrate is 0.08~0.12mm.

6. The preparation method according to claim 5, characterized in that, The drying temperature is 60~70℃, and the drying time is 10~15min.

7. The preparation method according to claim 6, characterized in that, The number of holes is 19, the diameter of each hole is 0.45mm, and the 19 holes are arranged in a hexagonal pattern. The baking temperature is 60~70℃ and the baking time is 10~20min.

8. The flexible patch dry electrode obtained by the preparation method according to any one of claims 1 to 7.

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