A flexible electrode, its preparation method and application

Abstract

This invention discloses a flexible electrode, its preparation method, and its applications. The flexible electrode can be attached to human skin to detect physiological electrical signals. It comprises an upper electrode material, a porous support layer, and a lower electrode material stacked sequentially. The upper and lower electrode materials are self-healing electrode materials, comprising polyborosiloxane, conductive microparticles, and a coupling agent. The porous support layer is a porous SEBS film. The flexible electrode of this invention is human-friendly and can be used in complex motion scenarios where conventional commercial electrodes are difficult to apply. It overcomes problems such as electrode detachment due to movement, skin electrode contact impedance easily affected by deformation, interference from sweat and temperature, and skin allergies caused by long-term wear. It exhibits good skin conformability, high and low temperature performance, wide application scenarios, and excellent stability in use.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a flexible electrode that conforms well to the skin and is suitable for complex motion states, as well as its preparation method and application. Background Technology

[0002] Electrode pads are devices attached to the surface of the human body to sense, collect, and transmit physiological electrical signals (such as electrocardiogram (ECG), electroencephalogram (EEG), and electromyogram (EMG). Existing electrode pads typically rely on electrode materials and dressings for direct support, making them prone to detachment from the skin or poor contact. This leads to unstable detection signals and affects the results of physiological electrical signal detection. Especially during electrical signal detection under load, the movements of the body during exercise can easily stretch the electrode pads and cause excessive sweating, leading to detachment or poor skin contact, generating noise interference, or even failing to collect any electrical signal, thus affecting the accuracy of electrical signal acquisition. Summary of the Invention

[0003] This invention provides a flexible electrode, its preparation method, and its application, to solve the technical problem mentioned in the background art that existing electrode sheets are difficult to meet the detection requirements under complex motion conditions.

[0004] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A flexible electrode includes an upper electrode material, a porous support layer, and a lower electrode material stacked sequentially; the upper and lower electrode materials are self-healing electrode materials, which include polyborosiloxane, conductive microparticles, and a coupling agent; the porous support layer is a porous SEBS thin film.

[0005] The design concept of the above technical solution is that the present invention adopts a "sandwich" layered structure, with a porous SEBS film as the middle skeleton layer and self-healing electrode material as the upper and lower layers, which are pressed together to form a flexible electrode. The self-healing electrode material, formed by polyborosiloxane, conductive microparticles and coupling agent, has semi-fluidity. In a low shear force environment, it exhibits a flexible colloidal state with poor fluidity, while under high shear force, it will exhibit shear thickening. The lower electrode material can fill the grooves on the surface of human skin to form physical adsorption. It can stably adhere to the skin in a static state and deform together with the skin in a moving state, which can prevent peeling during movement. The upper electrode material can also provide a conductive interface. Under higher shear force (tearing, etc.), it can be peeled off from the skin surface as a whole without damaging the skin. At the same time, the SEBS film, as the middle skeleton layer, has air permeability and can also provide resilience for the flexible electrode, preventing irreversible permanent deformation of the electrode material when the skin undergoes large deformation during vigorous movement, thus ensuring the overall stability of the flexible electrode.

[0006] In addition to the aforementioned effects, the inventors unexpectedly discovered that combining porous SEBS films and self-healing electrode materials in a specific structural combination can significantly improve the high and low temperature performance of flexible electrodes. This is manifested in two ways: firstly, the flexible electrodes of this invention exhibit low skin contact resistance in both extremely low and high temperature environments, indicating their performance over a wide temperature range; secondly, after being stretched at extremely low and high temperatures, the resistance remains stable at different stretching rates, meaning that the flexible electrodes of this invention can be used stably under varying degrees of motion and measurement conditions. This improved high and low temperature performance of the flexible electrodes greatly expands their application scenarios and flexibility.

[0007] As a further preferred embodiment of the above technical solution, the thicknesses of the upper electrode material, the porous support layer, and the lower electrode material are all 10~500μm. As a further preferred embodiment of the above technical solution, the ratio of polyborosiloxane to conductive microparticles in the self-healing electrode material is (1~3):(0.3~3).

[0008] As a further preferred embodiment of the above technical solution, the conductive particles are composed of zero-dimensional conductive materials, one-dimensional conductive materials, and two-dimensional conductive materials; the zero-dimensional conductive material is conductive carbon black, the one-dimensional conductive material includes at least one of silver nanowires and carbon nanotubes, and the two-dimensional conductive material includes at least one of silver flakes and graphene. The mass ratio of the zero-dimensional conductive material, one-dimensional conductive material, and two-dimensional conductive material is (0.1~1):(0.1~1):(0.1~1). Through the synergistic effect of the three, a three-dimensional conductive network of "points, lines, and surfaces" is formed, improving the conductivity of the electrode material.

[0009] As a further preferred embodiment of the above technical solution, the self-healing electrode material is prepared by the following method: (1) Add the polyborosiloxane to a solvent and stir until completely dissolved to obtain a polyborosiloxane solution; add conductive microparticles to the polyborosiloxane solution and ultrasonically disperse them evenly to obtain a mixed solution; (2) The solvent is removed by heating and evaporating the mixed solution to obtain the self-healing electrode material.

[0010] This invention utilizes a solution-processing method to obtain a self-healing electrode material. This material exhibits both percolation and tunneling effects, resulting in good electrical conductivity. The polyborosiloxane alkyl resin contains numerous reversible B-O bonds, causing the material to exhibit a semi-fluid, flexible colloidal state under low shear stress. However, under high shear stress, the numerous B-O bonds fail to break quickly enough, leading to shear thickening and a rapid increase in modulus, resulting in a solid state. Skin contact is facilitated by the material's semi-fluid nature, filling the grooves on the skin surface and forming physical adsorption. Its semi-solid nature ensures that the electrode shape remains unchanged, allowing it to actively adapt to the skin's contours and overcome the limitations imposed by skin hair.

[0011] As a further preferred embodiment of the above technical solution, the ultrasonic dispersion time in step (1) is 0.5~1 h.

[0012] As a further preferred embodiment of the above technical solution, the porous SEBS film is prepared by the following method: (1) To prepare or use SEBS solution, add water-soluble salt powder to the SEBS solution and disperse it evenly; (2) The SEBS solution containing water-soluble salt powder is scraped onto the carrier and heated to dry and remove the solvent to solidify and form an intermediate product. (3) The intermediate product is washed with deionized water to obtain the porous SEBS film.

[0013] The present invention uses the salt dissolution method to prepare porous SEBS films, which has the following advantages: (1) The preparation process is simple, the method is green and low cost, and strong acid solvents are not required; (2) The film thickness and size are easier to control; (3) The porosity can be adjusted by simply changing the amount of salt particles, which is efficient and economical.

[0014] As a further preferred embodiment of the above technical solution, the porous SEBS film is a maleic anhydride-modified porous SEBS film; the maleic anhydride-modified porous SEBS film is prepared by the following method: (1) Dissolve SEBS particles and maleic anhydride in toluene solvent at a mass ratio of (1~100):1 to obtain a modified SEBS solution; (2) Add water-soluble salt powder to the modified SEBS solution and disperse it evenly; (3) The SEBS solution containing water-soluble salt powder is scraped onto the carrier and heated to dry and remove the solvent to solidify and form an intermediate product. (4) The intermediate product is washed with deionized water to obtain the maleic anhydride modified porous SEBS film.

[0015] Since SEBS molecular chains do not contain polar or reactive groups, grafting SEBS with maleic anhydride (SEBS-g-MAH) can significantly improve the interfacial adhesion between porous SEBS films and self-healing electrode materials.

[0016] As a further preferred embodiment of the above technical solution, the mass ratio of the SEBS solution to the water-soluble salt powder is (1~5):(1~2).

[0017] Based on the same technical concept, the present invention also provides a method for preparing the flexible electrode described above, comprising the following operations: The upper electrode material, the porous SEBS film, and the lower electrode material are stacked and then pressed together in a press to obtain the flexible electrode. During the pressing process, the upper and lower electrode materials penetrate the pores of the porous SEBS film, thereby achieving conductivity between the upper and lower layers.

[0018] Based on the same technical concept, this invention also provides an application of the flexible electrode described above, which is used to attach to human skin to detect physiological electrical signals. In practical use, in order to facilitate the acquisition of raw physiological electrical signals such as electrocardiogram, electroencephalogram, or electromyogram using the flexible electrode as an interface, the flexible electrode is cut into any size and shape (it can be equipped with a lead wire for easy connection with alligator clips), and transferred to a dressing for easy storage and carrying. When in use, simply peel off the release film and attach it to the skin for fixation.

[0019] The present invention has the following beneficial effects: The flexible electrode of this invention is breathable and can achieve long-term conformal adhesion between the electrode and the skin. It can maintain the stability of skin-electrode impedance during skin stretching, meet the needs of long-term physiological electrical signal detection during exercise, and can be used in complex sports scenarios where conventional commercial electrodes are difficult to apply. It overcomes problems such as electrode detachment caused by exercise and excessive sweating, skin electrode contact impedance being easily deformed, interference from sweat and temperature, and skin allergies caused by long-term wear. It has good skin conformity, high and low temperature performance, wide application scenarios, and good stability in use. Attached Figure Description

[0020] Figure 1 A photograph of the stacked upper electrode material, porous SEBS film and lower electrode material of Example 1; Figure 2 A photograph of the flexible electrode from Example 1; Figure 3 This is a photograph of the flexible electrode connection lead of Example 1; Figure 4 A photograph of the flexible electrode in use according to Example 1; Figure 5The sheet resistance test results of each sample in Example 1 after being stretched at different temperatures and with different stretching rates are shown. Figure 6 The results are the skin contact impedance test results for each sample in Example 1. Detailed Implementation

[0021] The present invention will be described in detail below with reference to embodiments and accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims. Example

[0022] The flexible electrode of this embodiment includes an upper electrode material, a porous support layer, and a lower electrode material stacked sequentially. The upper and lower electrode materials are self-healing electrode materials, comprising polyborosiloxane, silver flakes, silver nanowires, conductive carbon black, and a silane coupling agent. The mass ratio of silver flakes, silver nanowires, conductive carbon black, and polyborosiloxane is 1:1:1:3. The porous support layer is a porous SEBS film. The total thickness of the flexible electrode is 130 μm.

[0023] The flexible electrode in this embodiment is prepared by the following method: (1) Preparation of upper electrode material and lower electrode material: Add sufficient n-hexane solvent to polyborosiloxane and stir until completely dissolved to obtain polyborosiloxane solution; add silver sheet, silver nanowire, conductive carbon black and coupling agent to polyborosiloxane solution according to mass ratio, and ultrasonically disperse for 30 min to obtain mixed solution; place the mixed solution on a heating plate with magnetic stirring, evaporate the solvent to obtain self-healing electrode material, press the self-healing electrode material into a thin layer to obtain upper electrode material and lower electrode material.

[0024] (2) Preparation of SEBS porous film: First, SEBS particles were dissolved in toluene solvent to prepare a SEBS solution with a concentration of 50 mg / mL. Then, NaCl powder that had been thoroughly ground was added at a mass ratio of 1:1 between SEBS solution and NaCl. After vigorous stirring, the solution was coated onto a glass slide using a wet film preparation device. The solvent was removed by hot plate drying and the film was solidified. Finally, NaCl was removed by water washing to obtain a porous SEBS film.

[0025] (3) Stack the upper electrode material (50 μm thick), the porous SEBS film (50 μm thick), and the lower electrode material (50 μm thick), as follows: Figure 1 As shown, the flexible electrode of this embodiment is obtained by pressing it to a set thickness using a press. Figure 2 As shown.

[0026] The flexible electrode in this embodiment is used to attach to human skin to detect physiological electrical signals. In use, the flexible electrode is cut into a 2 cm diameter circular piece and equipped with a lead wire for easy connection with alligator clips. Figure 3 As shown. Further transfer it to a 3M dressing for easy storage and transport. When using, simply peel off the release film and apply it to the skin for fixation. For example... Figure 4 As shown.

[0027] Six flexible electrode samples prepared in this embodiment were labeled as 1 to 6. Samples 1 to 3 were left untreated, while samples 4 to 6 underwent the following temperature change pretreatment procedures: ① room temperature to 40℃, stored at 40℃ for 2 hours; ② 40℃ to -40℃, stored at -40℃ for 2 hours; ③ -40℃ to 40℃; the temperature change rate was 1℃ / min. The sheet resistance of different samples at various tensile rates (0%, 10%, 20%, 30%, 40%) was measured using a four-probe tester. Three measurements were taken for each tensile condition. After each measurement, the probe was lifted, the sample was rotated horizontally, and the test was continued. The average value was taken. The test results are shown in Table 1 and [Table data missing]. Figure 5 From Table 1 and Figure 5 It can be seen that the flexible electrode of the present invention can maintain a stable sheet resistance value within the range of 0~40% elongation under high and low temperature and temperature change conditions.

[0028] Table 1. Shear resistance test results of different samples after being stretched at different temperatures and with different tensile rates.

[0029] Eight flexible electrode samples prepared in this embodiment were divided into four groups, labeled A through D. Group A was left untreated, while groups B through D underwent the following temperature change pretreatment procedures: Group B: room temperature to 40°C, stored at 40°C for 2 hours; Group C: 40°C to -40°C, stored at -40°C for 2 hours; Group D: -40°C to 40°C; the temperature change rate was 1°C / min. Skin contact impedance tests were performed on each group of samples. The center-to-center distance between the two electrode pads in each group was 5 cm, and the scanning frequency range was 20 Hz to 10 kHz. The test results are as follows. Figure 6 As shown in Table 2, the test data at frequencies of 20 Hz, 100 Hz, 500 Hz, 1 kHz, and 10 kHz are presented. Figure 6 As shown in Table 2, each group of flexible electrodes exhibits low skin contact resistance and a wide operating temperature range under low temperature, high temperature, and temperature variation conditions.

[0030] Table 2. Skin contact impedance test data for each group of samples

[0031] Example 2: The flexible electrode of this embodiment includes an upper electrode material, a porous support layer, and a lower electrode material stacked sequentially. The upper and lower electrode materials are self-healing electrode materials, comprising polyborosiloxane, silver flakes, silver nanowires, conductive carbon black, and a coupling agent. The mass ratio of silver flakes, silver nanowires, conductive carbon black, and polyborosiloxane is 1:1:1:2. The porous support layer is a maleic anhydride-modified porous SEBS film. The total thickness of the flexible electrode is 45 μm.

[0032] The flexible electrode in this embodiment is prepared by the following method: (1) Preparation of upper electrode material and lower electrode material: Add sufficient n-hexane solvent to polyborosiloxane and stir until completely dissolved to obtain polyborosiloxane solution; add silver sheet, silver nanowire, conductive carbon black and coupling agent to polyborosiloxane solution according to mass ratio, and ultrasonically disperse for 60 min to obtain mixed solution; coat the mixed solution on a heating plate with magnetic stirring, evaporate the solvent to obtain self-healing electrode material, form a thin layer of self-healing electrode material to obtain upper electrode material and lower electrode material.

[0033] (2) Preparation of maleic anhydride modified SEBS porous film: First, SEBS particles and maleic anhydride were dissolved in toluene solvent at a mass ratio of 10:1 to prepare a modified SEBS solution with a concentration of 100 mg / mL. Then, NaCl powder that had been thoroughly ground was added at a mass ratio of 1:1 to the modified SEBS solution and NaCl. After vigorous stirring, the film was coated onto a glass slide using a wet film preparation device. The solvent was removed by hot plate drying and the film was solidified. Finally, the NaCl was removed by washing with water to obtain a maleic anhydride modified porous SEBS film.

[0034] (3) The upper electrode material (thickness 20μm), the porous SEBS film (thickness 20μm) and the lower electrode material (thickness 20μm) are stacked and pressed to the set thickness using a press to obtain the flexible electrode of this embodiment.

[0035] The flexible electrode in this embodiment is used to attach to human skin to detect physiological electrical signals. In use, the flexible electrode is cut into a 2 cm diameter disc and equipped with a lead wire for easy connection with alligator clips. It is then transferred to a 3M dressing for convenient storage and transport. When in use, simply peel off the release film and attach it to the skin for secure application.

[0036] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and modifications obtained without departing from the inventive concept should also be considered within the scope of protection of the present invention.

[0037] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A flexible electrode, characterized in that, It includes an upper electrode material, a porous support layer, and a lower electrode material stacked sequentially; the upper and lower electrode materials are self-healing electrode materials, which include polyborosiloxane, conductive microparticles, and a coupling agent; the porous support layer is a porous SEBS thin film.

2. The flexible electrode according to claim 1, characterized in that, The thicknesses of the upper electrode material, the porous support layer, and the lower electrode material are all 10~500μm.

3. The flexible electrode according to claim 1, characterized in that, In the self-healing electrode material, the ratio of polyborosiloxane to conductive microparticles is (1~3):(0.3~3).

4. The flexible electrode according to claim 3, characterized in that, The conductive particles are composed of zero-dimensional conductive materials, one-dimensional conductive materials and two-dimensional conductive materials; the zero-dimensional conductive material is conductive carbon black, the one-dimensional conductive material includes at least one of silver nanowires and carbon nanotubes, and the two-dimensional conductive material includes at least one of silver flakes and graphene.

5. The flexible electrode according to claim 4, characterized in that, The self-healing electrode material is prepared by the following method: (1) Add the polyborosiloxane to a solvent and stir until completely dissolved to obtain a polyborosiloxane solution; add conductive microparticles to the polyborosiloxane solution and ultrasonically disperse them evenly to obtain a mixed solution; (2) The solvent is removed by heating and evaporating the mixed solution to obtain the self-healing electrode material.

6. The flexible electrode according to claim 5, characterized in that, The ultrasonic dispersion time in step (1) is 0.5~1 h.

7. The flexible electrode according to any one of claims 1-6, characterized in that, The porous SEBS film was prepared by the following method: (1) To prepare or use SEBS solution, add water-soluble salt powder to the SEBS solution and disperse it evenly; (2) The SEBS solution containing water-soluble salt powder is scraped onto the carrier and heated to dry and remove the solvent to solidify and form an intermediate product. (3) The intermediate product is washed with deionized water to obtain the porous SEBS film.

8. The flexible electrode according to any one of claims 1-6, characterized in that, The porous SEBS film is a maleic anhydride-modified porous SEBS film; the maleic anhydride-modified porous SEBS film is prepared by the following method: (1) Dissolve SEBS particles and maleic anhydride in toluene solvent at a mass ratio of (1~100):1 to obtain a modified SEBS solution; (2) Add water-soluble salt powder to the modified SEBS solution and disperse it evenly; (3) The SEBS solution containing water-soluble salt powder is scraped onto the carrier and heated to dry and remove the solvent to solidify and form an intermediate product. (4) The intermediate product is washed with deionized water to obtain the maleic anhydride modified porous SEBS film.

9. A method for preparing a flexible electrode according to any one of claims 1-8, characterized in that, Includes the following operations: The upper electrode material, the porous SEBS film, and the lower electrode material are stacked and then pressed together in a press to obtain the flexible electrode.

10. The application of a flexible electrode according to any one of claims 1-8 or a flexible electrode prepared by the preparation method according to claim 9, characterized in that, The flexible electrode is used to attach to human skin to detect physiological electrical signals.

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