Graphene eeg electrode based on titania nanotube array and preparation method thereof

Abstract

The application discloses a kind of graphene EEG electrode based on titanium dioxide nanotube array and preparation method thereof, comprising the following steps: step 1, after pretreatment, titanium piece is connected to the positive pole of programmable linear direct current power supply and is used as working electrode, platinum piece electrode as counter electrode is connected to the negative pole of programmable linear direct current power supply, titanium piece and platinum piece electrode are placed in solution and react 0.5-2h, to make titanium dioxide nanotube array after anodic oxidation reaction occurs on the surface of the titanium piece, washing, obtain after oxidation titanium piece;Step 2, the after oxidation titanium piece is used as substrate, with methane as carbon source, using direct current arc plasma jet method to grow graphene on the substrate.The electrode does not need to smear conductive paste during use, comfortable to wear, easy to operate, contact well with scalp, also because its macroscopic size and microscopic titanium dioxide nanotube array evade the influence of hair on test to some extent, so as to reduce electrode scalp contact impedance.

Description

Technical Field

[0001] This invention belongs to the field of EEG electrode technology, specifically relating to a graphene EEG electrode based on titanium dioxide nanotube array and its preparation method. Background Technology

[0002] Electroencephalography (EEG), as a non-invasive method for recording brain electrical activity, is widely used in medical diagnosis, sleep assessment, emotion recognition, and thought control due to its high temporal resolution. To alleviate the pressure on public healthcare systems, medical rehabilitation services need to extend from hospital spaces to community living spaces to facilitate timely monitoring, early warning, and treatment. EEG testing also needs to evolve from static, single-session testing in hospital spaces to long-term, continuous activity monitoring in living spaces.

[0003] Electroencephalogram (EEG) electrodes are sensors used to collect and transmit bioelectrical potential signals from the human brain. Placing EEG electrodes on the scalp to record electroencephalograms (EEGs) is the most common method for EEG testing. This method can obtain high-quality EEG signals, but its drawbacks are also significant. The optimal EEG testing time for a subject is within one hour, while the placement of EEG electrodes requires a considerable amount of preparation time. This can negatively impact the subject's condition, directly affecting the acquisition of EEG signals.

[0004] In use, EEG electrodes can be categorized into wet electrodes, semi-dry electrodes, and dry electrodes based on the presence or absence of conductive gel at the electrode-skin interface. When placing traditional wet electrodes on the subject's head, conductive gel needs to be applied between the electrode and scalp to acquire high-quality EEG signals. The conductive gel rapidly forms a low-impedance electrolyte pathway between the electrode and scalp, ensuring the stability of the EEG signal. However, wet electrodes are unsuitable for portable EEG systems due to their complex operation, uncomfortable wear, and unsuitability for long-term EEG monitoring. Semi-dry electrodes work by designing a container containing a small amount of electrolyte inside the electrode. During use, pressure is applied to release the electrolyte, creating an ion channel between the electrode and scalp, reducing the electrode-scalp contact impedance. However, the disadvantage is that applying pressure can lead to uneven electrolyte release and may even damage the electrode. Dry electrodes, on the other hand, do not require conductive gel; they are simply placed on the subject's head for measurement. This improves the comfort of the subject to some extent, but the lack of an effective electrolyte pathway between the electrode and skin results in poorer EEG signal quality. Therefore, designing an electrode that is both comfortable to wear and capable of providing long-term monitoring of good EEG signals is of great research significance for fields such as brain-computer interfaces.

[0005] For example, in 2016, Chen et al. designed a flexible forehead EEG dry electrode based on conductive rubber. This electrode was made of a rubber substrate doped with conductive silver powder and had dimensions of 30 mm (L) × 18 mm (W) × 4 mm (H). When in contact with the scalp, it forms an arc-shaped surface, allowing for a closer contact with the scalp and a larger contact area with the skin compared to a planar electrode. However, the average forehead contact impedance for all subjects was 26.5 ± 16.2 kΩ, while the forehead contact impedance for a wet electrode was 12.8 ± 5.7 kΩ, indicating that the impedance of this dry electrode was relatively high. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a graphene EEG electrode based on a titanium dioxide nanotube array. This method first prepares a titanium dioxide nanotube array on a substrate titanium sheet by anodizing reaction using a programmable linear DC power supply. Then, graphene is grown on the oxidized titanium sheet using a DC plasma jet chemical vapor deposition diamond film device.

[0007] Another objective of this invention is to provide a graphene EEG electrode based on a titanium dioxide nanotube array obtained by the above preparation method. The graphene EEG electrode based on a titanium dioxide nanotube array does not require the application of conductive paste during use, is comfortable to wear, easy to operate, and has good contact with the scalp. Furthermore, due to its macroscopic size and microscopic titanium dioxide nanotube array, it avoids the influence of hair on the test to a certain extent, thereby reducing the electrode-scalp contact impedance.

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

[0009] A method for preparing a graphene EEG electrode based on a titanium dioxide nanotube array includes the following steps:

[0010] Step 1: Connect the pretreated titanium sheet to the positive terminal of the programmable linear DC power supply and use it as the working electrode. Connect the platinum sheet electrode, which serves as the counter electrode, to the negative terminal of the programmable linear DC power supply. Place the titanium sheet and the platinum sheet electrode in a solution and react for 0.5 to 2 hours to generate a titanium dioxide nanotube array after anodizing on the surface of the titanium sheet. Clean the surface to obtain the oxidized titanium sheet.

[0011] In step 1, the titanium sheet is circular with a diameter of 5-10 mm and a thickness of 0.8-1.5 mm.

[0012] In step 1, the solution is a mixture of glycerol, ultrapure water and ammonium fluoride, wherein the volume fraction of glycerol, the volume fraction of ultrapure water and the mass fraction of ammonium fluoride are in the ratio of (28-35):(4-5):(0.35-0.45), where the volume fraction is in mL and the mass fraction is in g.

[0013] In step 1, the output voltage of the programmable linear DC power supply is 19-20V.

[0014] In step 1, during the reaction, the solution is stirred at a stirring speed of 650-750 r / min.

[0015] In step 1, the pretreatment involves first polishing the titanium sheet with sandpaper, then ultrasonically cleaning it with alcohol and ultrapure water in sequence, and finally drying it.

[0016] In step 1, the cleaning process involves sequentially sonicating with alcohol and ultrapure water for 3-5 minutes each.

[0017] Step 2: Using the oxidized titanium sheet as a substrate and methane as a carbon source, graphene is grown on the substrate using a DC arc plasma jet method to obtain a graphene EEG electrode based on a titanium dioxide nanotube array.

[0018] In step 2, the DC arc plasma jetting method involves jetting plasma onto the oxidized titanium sheet for 4-5 minutes in an environment of hydrogen and inert gas, followed by introducing the carbon source for 3-4.5 minutes.

[0019] In step 2, the hydrogen and inert gas environment is achieved by introducing hydrogen and inert gas into the cavity where the oxidized titanium sheet is placed. The flow rates of the hydrogen and inert gas are both 1-5 L / min. The cavity pressure is 3000-3500 Pa. The pump pressure for inputting the carbon source into the cavity is 13000-14000 Pa. The arc current of the DC arc that generates the plasma is 100-120 A, the arc voltage is 50-65 V, and the arc power is 5000-7800 W.

[0020] In the above technical solution, the flow rate of the carbon source is 150-200 L / min.

[0021] The graphene EEG electrode based on titanium dioxide nanotube array obtained by the above preparation method.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) The graphene EEG electrode based on titanium dioxide nanotube array prepared in this invention uses a circular titanium sheet with a diameter of 6.5 mm as the substrate. The graphene EEG electrode based on titanium dioxide nanotube array has a small volume and can fit well with the subject's scalp when combined with the mold, and is safe and reliable.

[0024] (2) Titanium has the characteristics of good plasticity, good ductility and easy processing, non-toxicity and good biocompatibility. Titanium oxide is a novel nanostructure that can provide an effective and convenient channel for electron transfer. When the graphene EEG electrode of the titanium dioxide nanotube array comes into contact with the scalp, the electron transfer rate is improved, thereby reducing the contact resistance between the two.

[0025] (3) The outermost material of the graphene EEG electrode based on titanium dioxide nanotube array is graphene. Graphene has electrochemical properties such as wide electrochemical window, good electrochemical stability, low charge transfer resistance, fast electron transfer rate and strong anti-interference ability, making it an excellent material for EEG electrodes. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the graphene EEG electrode based on a titanium dioxide nanotube array prepared in Example 1 of the present invention.

[0027] Figure 2 This is an electrode mold diagram of the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 of the present invention.

[0028] Figure 3 SEM image of the titanium dioxide nanotube array prepared in Example 1 of this invention;

[0029] Figure 4 SEM image of the graphene grown in Example 1 of this invention;

[0030] Figure 5 The impedance diagram is shown during the frontal EEG test. FP1 represents the graphene EEG electrode prepared in Comparative Example 1, and F7 represents the traditional wet electrode - Ag / AgCl electrode.

[0031] Figure 6 The waveform diagram is shown in the blink time domain. FP1 represents the graphene EEG electrode prepared in Comparative Example 1, and F7 represents the traditional wet electrode - Ag / AgCl electrode.

[0032] Figure 7 Correlation diagram of blink signals between the graphene EEG electrode prepared for Comparative Example 1 and the conventional wet electrode - Ag / AgCl electrode;

[0033] Figure 8 The waveform diagram is shown in the time domain of the teeth biting image. FP1 represents the graphene EEG electrode prepared in Comparative Example 1, and F7 represents the traditional wet electrode - Ag / AgCl electrode.

[0034] Figure 9 Correlation diagram of teeth biting signals between the graphene EEG electrode prepared for Comparative Example 1 and the conventional wet electrode - Ag / AgCl electrode;

[0035] Figure 10 This is an impedance diagram of the occipital region during an electroencephalogram (EEG), where P... Z Represents a traditional wet electrode - Ag / AgCl electrode, O Z The graphene EEG electrode prepared as shown in Comparative Example 1;

[0036] Figure 11 The original signal waveforms are shown for when the eyes are open and closed, where P Z Represents a traditional wet electrode - Ag / AgCl electrode, O Z The graphene EEG electrode prepared as shown in Comparative Example 1;

[0037] Figure 12 The correlation diagram of the α-wave signal between the graphene EEG electrode prepared for Comparative Example 1 and the conventional wet electrode - Ag / AgCl electrode;

[0038] Figure 13 The impedance diagram is shown during the frontal EEG test. FP1 represents the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1, and F7 represents the traditional wet electrode - Ag / AgCl electrode.

[0039] Figure 14 The waveform diagram in the blink time domain is shown. FP1 represents the graphene EEG electrode based on titanium dioxide nanotube array, and F7 represents the traditional wet electrode - Ag / AgCl electrode.

[0040] Figure 15 The correlation diagram of blink signals between the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 and the traditional wet electrode - Ag / AgCl electrode;

[0041] Figure 16 The waveform diagram is shown in the time domain of teeth biting. FP1 represents the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 of this invention, and F7 represents the traditional wet electrode - Ag / AgCl electrode.

[0042] Figure 17 The correlation diagram of the teeth biting signal between the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 and the traditional wet electrode - Ag / AgCl electrode.

[0043] Figure 18 This is an impedance diagram of the occipital region during an electroencephalogram (EEG), where P... Z Represents a traditional wet electrode - Ag / AgCl electrode, O Z The graphene EEG electrode based on a titanium dioxide nanotube array prepared in Example 1;

[0044] Figure 19 These are the original waveforms with eyes open and closed, where P Z Represents a traditional wet electrode - Ag / AgCl electrode, OZ The graphene EEG electrode based on a titanium dioxide nanotube array prepared in Example 1;

[0045] Figure 20 The correlation diagram of α-wave signals between the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 and the traditional wet electrode - Ag / AgCl electrode.

[0046] Figure 21 The experimental spectrum of the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 is shown. The solid line represents the open state and the dashed line represents the closed state.

[0047] Figure 22 The image shows the experimental spectrum of a traditional wet electrode-Ag / AgCl electrode, where the solid line represents the open state and the dashed line represents the closed state. Detailed Implementation

[0048] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0049] The relevant instruments and equipment used in the specific embodiments of this invention are as follows:

[0050] Programmable linear DC power supply: Model DP832A, RIGOL.

[0051] Thermostatic magnetic stirrer: Model B11-2, Shanghai Sile Instruments Co., Ltd.;

[0052] Ultrasonic cleaner: Model KQ2200E;

[0053] DC plasma jet chemical vapor deposition equipment for diamond films: Hebei Provincial Laser Research Institute;

[0054] Traditional wet electrode - Ag / AgCl electrode: Beijing Qingjing Electronic Technology Co., Ltd.;

[0055] Grael EEG device: A 32-lead EEG acquisition device from Neuroscan, Australia, model Grael.

[0056] The sources of the medicines used in the specific embodiments of the present invention are as follows:

[0057] Glycerol: content not less than 99.0%, Tianjin Damao Chemical Reagent Factory;

[0058] Ammonium fluoride: content not less than 96.0%, Tianjin Kewei Co., Ltd.

[0059] Example 1

[0060] A method for preparing a graphene EEG electrode based on a titanium dioxide nanotube array includes the following steps:

[0061] Step 1: Connect the pretreated titanium sheet to the positive terminal of a programmable linear DC power supply as the working electrode, and connect the platinum sheet as the counter electrode to the negative terminal of the programmable linear DC power supply. Place the titanium and platinum sheets in a solution and react for 1 hour. During this process, the solution is stirred at 700 r / min on a constant-temperature magnetic stirrer to induce anodizing on the titanium sheet surface, forming a titanium dioxide nanotube array. The titanium sheet is then ultrasonically treated with alcohol and ultrapure water for 5 minutes each to obtain the oxidized titanium sheet. The programmable linear DC power supply has an output voltage of 19.9V and an output current of 0.030A. The titanium sheet is a circle with a diameter of 6.5 mm and a thickness of 1 mm. The pretreatment process involves using a 70-mesh (212 μm) filter. The titanium sheet was polished with coarse sandpaper and then with fine sandpaper of 220 grit (68 μm). After polishing, it was placed in an ultrasonic cleaner and ultrasonically cleaned for 5 minutes each with 99.7 wt% alcohol (with the remaining 0.3 wt% being water) and ultrapure water. The cleaned titanium sheet was then dried at 70°C for 5 minutes under an infrared lamp. The solution was prepared by adding a mixture of glycerol, ultrapure water, and ammonium fluoride to a 50 ml beaker. The beaker was placed in an ultrasonic cleaner and stirred with a glass rod while ultrasonicating until the solution was homogeneous. The volume ratio of glycerol, ultrapure water, and ammonium fluoride was 35:5:0.39. The volume ratio is in mL and the mass ratio is in g.

[0062] Step 2: Place the oxidized titanium sheet into a DC plasma jet chemical vapor deposition (DCPL) diamond film deposition equipment. Using the oxidized titanium sheet as a substrate and methane as a carbon source, graphene is grown on the substrate using a DC arc plasma jet method. The DC arc plasma jet method operates as follows: Place the oxidized titanium sheet into the cavity of the DC plasma jet chemical vapor deposition (DCPL) diamond film deposition equipment and evacuate the cavity. When the cavity pressure reaches 1000 Pa, introduce hydrogen and argon into the cavity to create a hydrogen and inert gas environment. The flow rate of both hydrogen and argon is 2 L / min. When the cavity pressure reaches 3200 Pa, activate the magnetic field control and adjust the magnetic field voltage to 6 V to generate the arc current of the DC arc plasma. Adjust the current to 120A, arc voltage to 63V, and arc power to 7560W. Start the arc power control switch, preheat for 5 minutes, ignite to generate a DC arc, and spray plasma onto the oxidized titanium sheet for 5 minutes. Then, introduce a carbon source into the cavity for 4.5 minutes (flow rate of 200L / min) with a pump pressure of 13300Pa to grow graphene. Turn off the DC plasma jet chemical vapor deposition diamond film equipment to obtain a graphene EEG electrode based on a titanium dioxide nanotube array. During the growth process, maintain a distance of 1.8cm between the oxidized titanium sheet and the DC arc of the plasma. The growth temperature measured by an infrared thermometer during the growth process is between 1100 and 1180℃.

[0063] Comparative Example 1

[0064] A method for preparing a graphene EEG electrode includes the following steps:

[0065] Step 1: Pre-treat the titanium sheet. The titanium sheet is a circle with a diameter of 6.5 mm and a thickness of 1 mm. The pre-treatment involves polishing the titanium sheet with 70-grit (212 μm) coarse sandpaper and then polishing it with 220-grit (68 μm) fine sandpaper. After polishing, place it in an ultrasonic cleaner and ultrasonically clean it for 5 minutes each with 99.7 wt% alcohol (with the remaining 0.3 wt% being water) and ultrapure water. Then, place the cleaned titanium sheet under an infrared lamp and dry it at 70°C for 5 minutes.

[0066] Step 2: Place the titanium sheet into a DC plasma jet chemical vapor deposition (CVD) diamond film equipment. Using the titanium sheet as a substrate and methane as a carbon source, graphene is grown on the substrate using a DC arc plasma jet method. The operation steps of the DC arc plasma jet method are as follows: Place the titanium sheet in the cavity of the DC plasma jet CVD diamond film equipment and evacuate the cavity. When the cavity pressure reaches 1000 Pa, introduce hydrogen and argon gas into the cavity to create a hydrogen and inert gas environment. The flow rate of hydrogen and argon gas is 2 L / min. When the cavity pressure reaches 3200 Pa, activate the magnetic field control to adjust the voltage to 6V, generating a DC arc plasma. The arc current was adjusted to 120A, the arc voltage to 63V, and the arc power to 7560W. The arc power control switch was turned on, and the circuit was preheated for 5 minutes. The arc was then ignited to generate a DC arc, which was used to spray plasma onto the titanium sheet for 5 minutes. A carbon source was then introduced into the cavity for 4.5 minutes (flow rate of 200L / min) with a pump pressure of 13300Pa to grow graphene. The DC plasma jet chemical vapor deposition diamond film equipment was then turned off to obtain a graphene EEG electrode. During the growth process, the distance between the titanium sheet and the DC arc of the plasma was maintained at 1.8cm. The growth temperature measured by an infrared thermometer during the growth process was between 1100 and 1180℃.

[0067] The graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 and the graphene EEG electrode prepared in Comparative Example 1 were soldered together with signal lines. Three conventional wet electrodes - Ag / AgCl electrodes, abrasive paste, conductive paste, syringes, cleanroom wipes, medical tape, and Grael EEG equipment were prepared.

[0068] Signal acquisition:

[0069] (1) Collecting EEG signals by blinking and clenching the teeth.

[0070] The subject's mastoid process behind the ear was cleaned with a scrub. Two conventional wet electrodes (Ag / AgCl electrodes) were then injected with 40 μL of conductive paste using a syringe and secured to the mastoid process with medical tape. One electrode served as a reference electrode, and the other as a ground electrode. A third conventional wet electrode (Ag / AgCl electrode) was injected with 40 μL of conductive paste using a syringe. The graphene EEG electrode prepared in Comparative Example 1 was injected with 5 μL of saturated saline (room temperature 20-25℃) using a syringe. These electrodes were placed at two adjacent locations above the brow bone on the forehead and secured with a headband.

[0071] The graphene EEG electrode prepared in Comparative Example 1 and a third conventional wet electrode—Ag / AgCl—were connected to an amplifier. A sampling rate of 4096 was set (4096 potential difference data points were acquired per second) to begin recording the frontal impedance value. Figure 5 As shown.

[0072] In the blink signal test, subjects blinked at 2s, 5s, and 8s, and the results were as follows: Figure 6 As shown, in the teeth-clenching signal test, the subjects clenched their teeth at 2s, 5s, and 8s, and the results were as follows. Figure 8 As shown.

[0073] The processing results of EEG signals acquired using MATLAB, such as Figure 7 As shown, the correlation between the blink signal of the graphene EEG electrode and the traditional wet electrode - Ag / AgCl electrode can be obtained.

[0074] The processing results of EEG signals acquired using MATLAB, such as Figure 9 As shown, the correlation between the teeth biting signal of the graphene EEG electrode and the traditional wet electrode - Ag / AgCl electrode can be obtained.

[0075] The graphene EEG electrode based on titanium dioxide nanotube array obtained in Example 1 was subjected to the same experimental procedures as the graphene EEG electrode obtained in Comparative Example 1.

[0076] Testing was performed using a Grael EEG device and Curry8 software. The graphene EEG electrode based on a titanium dioxide nanotube array from Example 1 and a third conventional wet electrode—Ag / AgCl—were connected to an amplifier. A sampling rate of 4096 was set to begin recording the frontal impedance value. Figure 13 As shown, FP1 represents a graphene EEG electrode based on a titanium dioxide nanotube array, and F7 represents a traditional wet electrode - an Ag / AgCl electrode.

[0077] In the blink signal test, subjects blinked at 2s, 5s, and 8s, and the results were as follows: Figure 14 As shown, in the teeth-clenching signal test, the subjects clenched their teeth at positions of 2s, 5s, and 8s, and the results were as follows. Figure 16 As shown.

[0078] The processing results of EEG signals acquired using MATLAB, such as Figure 15 As shown, the correlation between the blink signal of the graphene EEG electrode based on titanium dioxide nanotube array and the traditional wet electrode - Ag / AgCl electrode can be obtained.

[0079] The processing results of EEG signals acquired using MATLAB, such as Figure 17 As shown, the correlation between the teeth-grinding signal of the graphene EEG electrode based on titanium dioxide nanotube array and the traditional wet electrode - Ag / AgCl electrode can be obtained.

[0080] (2) Apply a scrub to the mastoid process behind the subject's ear. Using a syringe, apply 40 μL of conductive paste to two conventional wet electrode-Ag / AgCl electrodes and then secure them to the subject's mastoid processes with medical tape. One electrode serves as a reference electrode, and the other as a ground electrode. Select two adjacent horizontal positions in the occipital region of the subject's head and place a third conventional wet electrode-Ag / AgCl electrode and the graphene EEG electrode prepared in Comparative Example 1, respectively, and secure them with a headband. The conventional wet electrode-Ag / AgCl electrode requires 40 μL of conductive paste applied with a syringe, while the graphene EEG electrode requires 5 μL of saturated saline solution (room temperature 20-25℃) applied with a syringe.

[0081] Testing was conducted using a Grael EEG device and Curry8 software. The graphene EEG electrode from Comparative Example 1 and a third conventional wet electrode—an Ag / AgCl electrode—were connected to an amplifier. A sampling rate of 4096 was set to begin recording the impedance values ​​of the occipital region. Figure 10 As shown, where P Z Represents a traditional wet electrode - Ag / AgCl electrode, O Z This represents a graphene EEG electrode. In the alpha wave acquisition experiment, the subject first kept their eyes closed for 5 seconds, then kept their eyes open for 5 seconds, obtaining the original waveforms with eyes open and closed, as shown below. Figure 11 As shown.

[0082] Processing EEG signals acquired using MATLAB, such as... Figure 12 As shown, the correlation between the α-wave signals of the graphene EEG electrode and the traditional wet electrode - Ag / AgCl electrode can be obtained.

[0083] The graphene EEG electrode based on titanium dioxide nanotube array obtained in Example 1 was subjected to the same experimental procedures as the graphene EEG electrode obtained in Comparative Example 1.

[0084] Using a Grael EEG device and Curry8 software, the graphene EEG electrode and wet electrode based on a titanium dioxide nanotube array prepared in Example 1 were connected to an amplifier. A sampling rate of 4096 was set to begin recording the frontal impedance value. Figure 18 As shown, where P Z Represents a traditional wet electrode - Ag / AgCl electrode, O Z This represents a graphene EEG electrode based on a titanium dioxide nanotube array. In the alpha wave acquisition experiment, the subject first kept their eyes closed for 5 seconds, then kept their eyes open for 5 seconds, obtaining the original waveforms with eyes open and closed, as shown below. Figure 19 As shown.

[0085] Processing EEG signals acquired using MATLAB, such as... Figure 20As shown, the correlation between the α-wave signal of the graphene EEG electrode based on titanium dioxide nanotube array and the traditional wet electrode - Ag / AgCl electrode can be obtained.

[0086] The purpose of testing graphene EEG electrodes and graphene EEG electrodes based on titanium dioxide nanotube arrays after injecting saturated saline solution is to rapidly reduce the contact impedance between the electrode and the scalp, thus shortening the testing time. Direct measurement with graphene EEG electrodes or graphene EEG electrodes based on titanium dioxide nanotube arrays would require a longer waiting time for impedance reduction, potentially causing subject fatigue and affecting signal quality.

[0087] Depend on Figure 1 As can be seen, this is a schematic diagram of the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 of the present invention.

[0088] Depend on Figure 2 It is understood that this is the mold for the graphene EEG electrode based on titanium dioxide nanotube array prepared in Example 1 of the present invention. The mold is used to connect the electrode and the wire.

[0089] Depend on Figure 3 As can be seen, a uniform tubular structure can be observed.

[0090] Depend on Figure 4 It can be seen that the vertical graphene has a sheet-like structure.

[0091] Depend on Figure 5 It can be seen that the impedance of the graphene EEG electrode in Comparative Example 1 above the brow bone is 18.8kΩ, while the impedance of the traditional wet electrode -Ag / AgCl is 3.3kΩ.

[0092] Depend on Figure 6 It can be seen that the subjects blinked at 2, 5 and 8 seconds respectively, and there were corresponding negative peaks.

[0093] Depend on Figure 7 It can be seen that the correlation between the graphene EEG electrode and the traditional wet electrode - Ag / AgCl electrode in blink signal is 93.27%.

[0094] Depend on Figure 8 It can be seen that when the subjects clenched their teeth at 2, 5 and 8 seconds, corresponding sawtooth-shaped peaks appeared.

[0095] Depend on Figure 9 It can be seen that the correlation between the graphene EEG electrode and the traditional wet electrode - Ag / AgCl electrode in the teeth biting signal is 88.82%.

[0096] Depend on Figure 10 It can be seen that the impedance of the graphene EEG electrode in the occipital region of the brain is 26.0kΩ, while the impedance of the traditional wet electrode - Ag / AgCl electrode is 2.4kΩ.

[0097] Depend on Figure 11 As can be seen, the left side of the vertical line in the figure represents the subject's closed-eye state, with large and sparse waveform amplitudes, indicating the presence of alpha waves; the right side of the vertical line represents the subject's open-eye state, with small and dense waveform amplitudes, indicating the presence of beta waves. Alpha waves are spontaneous EEG signals generated in the occipital region of the back of the head when a person is at rest with their eyes closed.

[0098] Depend on Figure 12 It can be seen that the correlation between the α-wave signal of the graphene EEG electrode and the traditional wet electrode - Ag / AgCl electrode can reach 90.74%.

[0099] Depend on Figure 13 It can be seen that the impedance of the graphene EEG electrode based on titanium dioxide nanotube array above the forehead brow bone is 13.5kΩ, while the impedance of the traditional wet electrode - Ag / AgCl electrode is 3.0kΩ.

[0100] Depend on Figure 14 It can be seen that the subjects blinked at 2, 5 and 8 seconds respectively, and there were corresponding negative peaks.

[0101] Depend on Figure 15 It can be seen that the correlation between the blink signal of the graphene EEG electrode based on titanium dioxide nanotube array and the traditional wet electrode - Ag / AgCl electrode is 97.70%.

[0102] Depend on Figure 16 It can be seen that when the subjects clenched their teeth at 2, 5 and 8 seconds, corresponding sawtooth-shaped peaks appeared.

[0103] Depend on Figure 17 It can be seen that the correlation between the graphene EEG electrode based on titanium dioxide nanotube array and the traditional wet electrode - Ag / AgCl electrode in terms of teeth biting signal is 94.27%.

[0104] Depend on Figure 18 It can be seen that in the occipital region of the head, the impedance of the graphene EEG electrode based on titanium dioxide nanotube array is 20.5kΩ, while the impedance of the traditional wet electrode - Ag / AgCl electrode is 2.5kΩ.

[0105] Depend on Figure 19 As can be seen, the left side of the vertical line in the figure represents the subject's closed-eye state, with large and sparse waveform amplitudes, indicating the presence of alpha waves; the right side of the vertical line represents the subject's open-eye state, with small and dense waveform amplitudes, indicating the presence of beta waves.

[0106] Depend on Figure 20 It can be seen that the correlation between the α-wave signal of the graphene EEG electrode based on titanium dioxide nanotube array and the traditional wet electrode - Ag / AgCl electrode can reach 95.59%.

[0107] Figure 21 , Figure 22 The images show the open-eye and closed-eye experimental spectra of a graphene EEG electrode based on a titanium dioxide nanotube array, processed using Origin 2018 software, and the open-eye and closed-eye experimental spectra of a traditional wet electrode-Ag / AgCl electrode, processed using Origin 2018 software. Figure 21 and Figure 22 The peak values ​​indicate that a person in a closed-eye, resting state will produce an alpha rhythm of 8-13 Hz. The amplitude of the alpha rhythm can be used as a standard to measure the quality of EEG electrodes. The alpha amplitude measured by the graphene EEG electrode based on titanium dioxide nanotube array is about 10 μV, while the alpha amplitude measured by the traditional wet electrode - Ag / AgCl electrode is about 8 μV. It can be seen that the waveform quality of the graphene EEG electrode based on titanium dioxide nanotube array is higher and better than that of the traditional wet electrode - Ag / AgCl electrode.

[0108] 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. The application of a graphene EEG electrode based on a titanium dioxide nanotube array in the acquisition of electroencephalogram (EEG) signals, characterized in that, The preparation method of graphene EEG electrode includes the following steps: Step 1: Connect the pretreated titanium sheet to the positive terminal of a programmable linear DC power supply as the working electrode, and connect the platinum electrode, which serves as the counter electrode, to the negative terminal of the programmable linear DC power supply. Place the titanium sheet and platinum electrode in a solution and react for 0.5-2 h to generate a titanium dioxide nanotube array after anodizing on the surface of the titanium sheet. Clean the titanium sheet to obtain the oxidized titanium sheet. In Step 1, the solution is a mixture of glycerol, ultrapure water, and ammonium fluoride, wherein the volume fraction of glycerol, the volume fraction of ultrapure water, and the mass fraction of ammonium fluoride are (28-35):(4-5):(0.35-0.45), with volume fractions in mL and mass fractions in g. The output voltage of the programmable linear DC power supply is 19-20 V. Step 2: Using the oxidized titanium sheet obtained in Step 1 as a substrate and methane as a carbon source, graphene is grown on the substrate using a DC arc plasma jetting method to obtain a graphene EEG electrode based on a titanium dioxide nanotube array. The DC arc plasma jetting method involves jetting plasma onto the oxidized titanium sheet for 4-5 minutes in a hydrogen and inert gas environment, followed by introducing the carbon source for 3-4.5 minutes at a flow rate of 150-200 L / min. The hydrogen and inert gas environment is achieved by introducing hydrogen and inert gas into the cavity containing the oxidized titanium sheet, with each gas flow rate of 1-5 L / min. The cavity pressure is 3000-3500 Pa, and the pump pressure for inputting the carbon source is 13000-14000 Pa. The arc current of the DC arc generating the plasma is 100-120 A, and the arc voltage is 50-65 A. V, arc power is 5000~7800 W.

2. The use according to claim 1, characterized in that, In step 1, the titanium sheet is circular with a diameter of 5-10 mm and a thickness of 0.8-1.5 mm.

3. The use according to claim 2, characterized in that, In step 1, during the reaction, the solution is stirred at a stirring speed of 650~750 r / min.

4. The use according to claim 3, characterized in that, In step 1, the pretreatment involves first polishing the titanium sheet with sandpaper, then ultrasonically cleaning it with alcohol and ultrapure water in sequence, and finally drying it.

5. The use according to claim 4, characterized in that, In step 1, the cleaning process involves sequentially sonicating with alcohol and ultrapure water for 3-5 minutes each.

Images