Electrode-skin contact surface parameter model establishing method and measuring method

Abstract

The invention discloses an electrode-skin contact surface parameter model establishing method and a measuring method.The electrode-skin contact surface parameter model establishing method is based on an equivalent circuit model of an electric double-layer capacitor, and information of resistance (real part) and reactance (imaginary part) under different frequencies is described through a complex impedance spectrum; the information can fit parameters of elements in the model. Besides, when biological cells are placed in an alternating current electric field, relaxation phenomena of alpha dispersion and beta dispersion occur in dielectric response of the cells, so that the impedance spectrum can also reflect structural characteristics of the cells, and is crucial for quantifying, understanding and optimizing electrode-tissue interface characteristics. The invention relates to a nerve regulation technology.

Description

Technical Field

[0001] The present invention relates to neuromodulation techniques, and in particular, to a method for establishing and measuring a parameter model of an electrode-skin contact surface. Background Art

[0002] Transcranial electrical stimulation (tES) is a technique for non-invasively regulating cortical nerve activity using low-intensity currents. By adjusting the stimulation location, current intensity, and waveform, the regulation purpose can be achieved, and it has been widely used in the treatment of neuropsychiatric diseases, rehabilitation of brain function injuries, cognitive function regulation, etc. The transcranial electrical stimulation device uses electrodes attached to the scalp to conduct the stimulation current, and usually a conductive medium (such as conductive paste, conductive gel, saline, etc.) is added between the electrode and the skin to reduce the contact impedance.

[0003] During the electrical stimulation process, skin damage is likely to occur, and the current damage mechanism is not yet clear. The occurrence of skin damage is related to various factors, including stimulation intensity, current density, conductive medium, skin condition, etc. Among these factors, reducing the stimulation intensity seems to be an absolutely effective option for reducing the risk of skin damage, but at the cost of reducing the stimulation intensity in the target area, it is not the optimal choice in most cases. In addition, these influencing factors can directly or indirectly affect the characteristics of the electrode-skin interface. For example, changes in current density may reflect whether the contact between the electrode and the skin is uniform and sufficient; changes in the electrode-tissue contact resistance may reflect changes in skin condition or conductive medium.

[0004] Therefore, obtaining detailed parameters of the electrode-skin contact surface helps to accurately evaluate the electrode-skin contact condition and understand the electrode-tissue characteristics, and provides assistance for reducing skin damage and promoting electrode design. Summary of the Invention

[0005] To at least partly solve one of the technical problems existing in the prior art, the purpose of the present invention is to provide a method for establishing and measuring a parameter model of an electrode-skin contact surface, which can accurately evaluate the electrode-skin contact condition and understand the electrode-tissue characteristics, and provides assistance for reducing skin damage and promoting electrode design.

[0006] The first technical solution adopted by the present invention is:

[0007] A method for establishing a parameter model of an electrode-skin contact surface, comprising the following steps:

[0008] Establish an electrode-skin complex impedance formula:

[0009] z(t) = a(t) + jb(t);

[0010] A continuous exponential swept-frequency current with an angular frequency of ω is applied to the stimulation electrode as an excitation signal. The excitation signal is applied across the electrodes, and the resulting voltage is:

[0011] U(t) = z(t)e jωt ;

[0012] The voltage and current signals between the electrodes are synchronously sampled. The physical signal only contains the real part and cannot reflect the imaginary part. Therefore, the actual voltage signals U(t) and I(t) are as follows:

[0013]

[0014] Obtain two carrier signals;

[0015] Multiply the two carrier signals with the voltage signal respectively to obtain the real part and the imaginary part of the complex impedance:

[0016]

[0017] According to some embodiments of the present application, based on the electrode-skin complex impedance formula, an electrode-resistance complex impedance model is obtained:

[0018]

[0019] where R 1 , R 2 , K, β, and the complex impedance spectrum is used to fit the model parameters.

[0020] According to some embodiments of the present application, based on the Cole-Cole theory, parameter fitting is performed to obtain the origin coordinates and radius of the fitted arc:

[0021]

[0022] According to some embodiments of the present application, the complex impedance spectrum is fitted to a circle using the least squares method. Based on the center and radius of the circle and the intersection point with the real axis, R 1 , R 2 and β are calculated, and K is calculated according to the complex impedance spectrum.

[0023] According to some embodiments of the present application, after multiplying the two carrier signals with the voltage signal, the signal is passed through a low-pass filter with a cut-off frequency lower than twice the carrier frequency and a passband gain of 2.

[0024] According to some embodiments of the present application, the two carrier signals are respectively:

[0025]

[0026] According to some embodiments of the present application, one of the carrier signals Ci(t) is a current signal I(t), and performing a Hilbert transform on Ci(t) can obtain another carrier signal Cq(t).

[0027] The second technical solution adopted by the present invention is:

[0028] A method for measuring parameters of an electrode-skin contact surface, which is carried out based on the parameter model established by the above-mentioned method for establishing a parameter model of the electrode-skin contact surface, and includes the following steps:

[0029] Paste the electrode onto the scalp of the subject and turn on the electrical stimulation device;

[0030] The electrical stimulation device outputs a current signal I(t) and measures the voltage U(t) across the electrodes in real time;

[0031] Calculate the complex impedance at the current frequency through the amplitude and phase relationship between the measured voltage U(t) and the current I(t);

[0032] Measure the values of the complex impedance at different frequencies, and based on the parameter model established by the above-mentioned method for establishing a parameter model of the electrode-skin contact surface, depict the curve of the impedance changing with frequency in the complex plane, that is, the complex impedance spectrum.

[0033] The third technical solution adopted by the present invention is:

[0034] An electronic device, the electronic device includes a processor and a memory, and at least one instruction, at least one program, a code set or an instruction set is stored in the memory, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the above-mentioned method for establishing a parameter model of the electrode-skin contact surface.

[0035] The fourth technical solution adopted by the present invention is:

[0036] A computer-readable storage medium, in which at least one instruction, at least one program, a code set or an instruction set is stored, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by a processor to implement the above-mentioned method for establishing a parameter model of the electrode-skin contact surface.

[0037] The beneficial effects of the present invention are: Based on the equivalent circuit model of the double-layer capacitance, the present invention describes the information of resistance (real part) and reactance (imaginary part) at different frequencies through the complex impedance spectrum, and these information can fit the parameters of the components in the model. In addition, when biological cells are placed in an alternating electric field, the dielectric response of the cells shows relaxation phenomena of α dispersion and β dispersion. Therefore, the impedance spectrum can also reflect the structural characteristics of the cells, which is crucial for quantifying, understanding, and optimizing the characteristics of the electrode-tissue interface. Brief Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following introduces the accompanying drawings of the relevant technical solutions in the embodiments of the present invention or the prior art. It should be understood that the accompanying drawings in the following introduction are only for conveniently and clearly expressing some embodiments of the technical solutions of the present invention. For those skilled in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0039] Figure 1 is a schematic diagram of the electrode-skin equivalent circuit model;

[0040] Figure 2 is a schematic diagram of the impedance spectrum measurement circuit;

[0041] Figure 3 is a schematic diagram of the actual waveforms of the swept-frequency current and the swept-frequency voltage;

[0042] Figure 4 is the curve of the real part and the imaginary part of the complex impedance varying with frequency and the complex impedance spectrum;

[0043] Figure 5 is the schematic diagram after fitting according to the Cole-Cole theory parameters. Detailed Description of the Embodiments

[0044] The following details the embodiments of the present invention. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as a limitation of the present invention. For the step numbers in the following embodiments, they are only set for the convenience of elaboration and explanation, and no limitation is imposed on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0045] In the description of the present invention, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0046] In the description of the present invention, "several" means one or more, "multiple" means more than two, "greater than", "less than", "exceeding", etc. are understood not to include the recited number, and "above", "below", "within", etc. are understood to include the recited number. If "first" and "second" are described, they are only used to distinguish technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0047] In the description of the present invention, unless otherwise clearly defined, terms such as "arrangement", "installation", "connection", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0048] Example 1

[0049] This embodiment provides a method for establishing a parameter model of an electrode-skin contact surface, and its establishment idea is as follows:

[0050] When a metal electrode is placed in a physiological medium such as human tissue fluid, an interface will be formed between the two phases. In the metal electrode and the circuit system, charges are carried by electrons, while in the physiological medium, charges are carried by ions, including sodium ions, potassium ions, and chloride ions in the extracellular fluid. When the tissue is electrically stimulated, the charge carriers are converted from electrons in the metal electrode to ions in the electrolyte. This process involves two electrochemical mechanisms: non-Faraday reaction and Faraday reaction. In the non-Faraday reaction, the charge transfer does not involve the oxidation-reduction reaction of chemical substances, but a double-layer structure is formed on both sides of the interface. The enrichment or diffusion of charges on both sides of the double layer transfers current, and the electrical characteristics of this process are very similar to those of a flat capacitor. Therefore, the electrode-electrolyte interface capacitance is usually called the double-layer capacitance; in the Faraday reaction, the charge transfer is accompanied by the oxidation-reduction reaction of chemical substances, which is the process of electrons directly transferring from the electrode to the ions in the solution and follows Faraday's law, so it is called the Faraday reaction.

[0051] In the actual electrode-tissue interface, both of these reactions exist simultaneously, and the impedance model can be represented by an equivalent circuit as shown in Figure 1 The double-layer capacitance CPE formed by the non-Faraday reaction and the resistance R2 formed by the Faraday process are connected in parallel, and then connected in series with the resistance R1 of the biological tissue and the electrolyte. The model also includes the polarization voltage E formed by the electrode in the electrolyte solution.

[0052] Affected by the electrochemical effect, the impedance characteristics of the double-layer capacitance are different from those of an ideal capacitor. Its impedance phase angle is an approximately constant value. Therefore, a constant phase angle element (CPE) is used instead, and the impedance expression is as follows:

[0053]

[0054] Currently, the electrostimulation devices on the market generally have an impedance measurement function, which can measure the equivalent resistance between electrodes. The measurement of the equivalent resistance is affected by the excitation signal. The smaller the amplitude of the excitation signal, the higher the measured equivalent resistance. The excitation signals used by the devices of different manufacturers are different, resulting in different measured resistances under the same contact conditions, making the impedance measurement values between different devices not comparable.

[0055] In addition, the equivalent resistance reflects to a certain extent the characteristics of the contact surface between the electrode and the skin. However, the change in the contact condition between the electrode and the skin may be manifested as a change in the resistance and capacitance parameters, or as a change in the β of the CPE element, while the equivalent resistance remains unchanged. The equivalent circuit model of the contact surface cannot be fully described only by the equivalent resistance.

[0056] In order to describe the characteristics of the electrode-skin contact surface in more detail and stably, the present invention is based on Figure 1 the equivalent circuit model shown, and proposes a method for establishing a parameter model to quantify the characteristics of the electrode-skin contact surface. Due to the capacitive device formed by the double electric layer, the overall presents a complex impedance, and the complex impedance measurement circuit is as Figure 2 shown. The electrostimulation device outputs a current signal I(t) of a specific frequency and measures the voltage U(t) across the electrodes in real time. The complex impedance at the current frequency can be calculated through the amplitude and phase relationship between the voltage and the current. By measuring the values of the complex impedance at different frequencies, a curve of the impedance changing with frequency in the complex plane can be drawn, that is, the complex impedance spectrum. The complex impedance spectrum describes the information of the resistance (real part) and reactance (imaginary part) at different frequencies. These information can fit the parameters of the components in the model. In addition, when biological cells are placed in an alternating electric field, the dielectric response of the cells shows relaxation phenomena of α dispersion and β dispersion. Therefore, the impedance spectrum can also reflect the structural characteristics of the cells, which is crucial for quantifying, understanding, and optimizing the characteristics of the electrode-tissue interface.

[0057] From the perspective of modulation and demodulation, the voltage signal can be regarded as the result of the amplitude modulation of the complex impedance to the current signal. According to the principle of orthogonal demodulation, when a complex signal modulates a carrier in the amplitude modulation process, the real part and the imaginary part of the complex signal are respectively modulated onto two orthogonal carriers. During demodulation, the received signal is demodulated using the same two orthogonal carriers as in the modulation process, so as to respectively recover the two components of the original signal. Therefore, by demodulating the voltage signal, the change of the complex impedance with time can be obtained. If the carrier frequency is set as a function of time, the change of the complex impedance with time can be mapped into a curve of the complex impedance changing with frequency, that is, the complex impedance spectrum.

[0058] Based on the above idea, the method for establishing the parameter model of the electrode-skin contact surface in the embodiments of the present application includes the following steps: S100. Establish the electrode-skin complex impedance formula:

[0059] z(t) = a(t) + jb(t);

[0060] S200. Apply a continuous exponential swept-frequency current with an angular frequency of ω as an excitation signal to the stimulation electrode. The excitation signal is applied to both ends of the electrode, and the generated voltage is:

[0061] U(t) = z(t)e jωt ;

[0062] S300. Synchronously sample the voltage and current signals between the electrodes. Since the physical signal only contains the real part and cannot reflect the imaginary part, the actual obtained voltage signals U(t) and I(t) are as follows:

[0063]

[0064] The swept-frequency current and voltage waveforms are referred to Figure 3 ;

[0065] S400. Obtain two carrier signals;

[0066] S500. Multiply the two carrier signals with the voltage signal respectively to obtain the real part and the imaginary part of the complex impedance:

[0067]

[0068] Refer to Figure 4 , Figure 4 In (A) of Figure 4 shows the curves of the real part and the imaginary part of the complex impedance changing with frequency when the frequency changes from 3 Hz to 100 Hz,

[0069] In (B) of

[0070]

[0071] where R 1 , R 2 , K, β, and use the complex impedance spectrum to fit the model parameters.

[0072] Furthermore, the existence of exponential and trigonometric functions in the model greatly increases the difficulty of parameter fitting. According to the Cole-Cole theory, the calculation can be simplified. The Cole-Cole theory was proposed by KSCole and RHCole to describe the frequency characteristics of multipolar dielectrics. According to the theory, when the frequency changes from zero to infinity, the complex impedance depicts an arc. The coordinates of the origin and radius of the arc after fitting are:

[0073]

[0074] The arc intersects the real axis at two points (R 1 +R 2 ,0) and (R 1 ,0), corresponding to the frequency of 0 and infinity respectively. The angle between the intersection point and the center of the circle and the imaginary axis is πβ / 2. β is between 0 and 1, and the smaller β is, the lower the center of the circle is. When the frequency varies within a limited range, the actual measured complex impedance spectrum is part of a semicircular arc, and K determines the starting and ending positions of the arc.

[0075] Furthermore, the least squares method is used to fit the complex impedance spectrum into a circle, and R is calculated based on the center and radius of the circle and the intersection with the real axis. 1 , R 2 and β, and K is calculated based on the complex impedance spectrum. So far, the parameters of the electrode-skin equivalent circuit model can be obtained, and the fitting results and parameters are as follows: Figure 5 Parameter R 1 The negative value is because the real electrode-skin interface cannot fully explain the measurement data due to the influence of measurement level, frequency conditions, model complexity and other issues. Especially at high frequencies, the impedance spectrum is no longer a circular arc, which leads to negative values ​​in the fitting results. However, these parameters can still reflect the characteristic differences of the electrode-skin interface and should be regarded as characteristic parameters of the complex impedance spectrum.

[0076] Furthermore, after the two carrier signals are multiplied by the voltage signal, the signals are passed through a low-pass filter with a cut-off frequency lower than twice the carrier frequency and a passband gain of 2.

[0077] Specifically, for two carrier signals, they are:

[0078]

[0079] One of the carrier signals Ci(t) is a current signal I(t), and another carrier signal Cq(t) can be obtained by performing Hilbert transform on Ci(t).

[0080] Example 2

[0081] This embodiment provides a method for measuring parameters of an electrode-skin contact surface, which is carried out based on the parameter model established by the above-mentioned parameter model establishment method for the electrode-skin contact surface, and includes the following steps:

[0082] S600. Paste the electrode onto the scalp of the subject and turn on the electrical stimulation device;

[0083] S700. The electrical stimulation device outputs a current signal I(t) and measures the voltage U(t) across the electrodes in real time;

[0084] S800. Calculate the complex impedance at the current frequency through the amplitude and phase relationship between the measured voltage U(t) and the current I(t);

[0085] S900. Measure the values of the complex impedance at different frequencies, and based on the parameter model established by the above-mentioned parameter model establishment method for the electrode-skin contact surface, depict the curve of the impedance varying with frequency in the complex plane, that is, the complex impedance spectrum.

[0086] Embodiment 3

[0087] This embodiment of the present invention further provides an electronic device, which includes a processor and a memory. At least one instruction, at least one program, a code set or an instruction set is stored in the memory, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the above-mentioned parameter model establishment method for the electrode-skin contact surface.

[0088] It can be understood that the memory may include a random access memory (RAM), or may also include a read-only memory (ROM). Optionally, the memory includes a non-transitory computer-readable storage medium. The memory can be used to store instructions, programs, codes, code sets or instruction sets. The memory may include a program storage area and a data storage area. Among them, the program storage area may store instructions for implementing the operating system, instructions for at least one function, instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data created according to the use of the server, etc.

[0089] The processor may include one or more processing cores. The processor uses various interfaces and circuits to connect various parts within the entire server. By running or executing instructions, programs, code sets, or instruction sets stored in the memory, and by invoking data stored in the memory, it performs various functions of the server and processes data. Optionally, the processor may be implemented in at least one of the hardware forms of digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor may integrate a combination of one or several of a central processing unit (CPU) and a modem, etc. Among them, the CPU mainly processes the operating system, application programs, etc.; the modem is used to process wireless communication. It can be understood that the above-mentioned modem may not be integrated into the processor and may be implemented separately by a single chip.

[0090] Since this electronic device is the electronic device corresponding to the closed-loop transcranial electrical stimulation method of the embodiments of the present invention, and the principle of solving problems by this electronic device is similar to that of this method, the implementation of this electronic device can refer to the implementation process of the above method embodiments, and the repeated parts will not be described again.

[0091] Embodiment 4

[0092] The embodiments of the present invention further provide a computer-readable storage medium, in which at least one instruction, at least one segment of program, code set, or instruction set is stored, and the at least one instruction, the at least one segment of program, the code set, or the instruction set is loaded and executed by a processor to implement the above-mentioned method for establishing a parameter model of the electrode-skin contact surface.

[0093] Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing relevant hardware through a program, and this program can be stored in a computer-readable storage medium. The storage medium includes read-only memory (ROM), random access memory (RAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), one-time programmable read-only memory (OTPROM), electrically-erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc memories, magnetic disc memories, tape memories, or any other computer-readable medium capable of carrying or storing data.

[0094] Since this storage medium is the storage medium corresponding to a closed-loop transcranial electrical stimulation method of the embodiments of the present invention, and the principle of solving problems by this storage medium is similar to that of this method, the implementation of this storage medium can refer to the implementation process of the above method embodiments, and the repeated parts will not be elaborated.

[0095] Embodiment 5

[0096] In some possible implementation manners, various aspects of the method of the embodiments of the present invention can also be implemented in the form of a program product, which includes program code. When the program product runs on a computer device, the program code is used to cause the computer device to execute the steps of a method for establishing a parameter model of an electrode-skin contact surface according to various exemplary implementation manners described above in this specification. Among them, the executable computer program code or "code" for executing each embodiment can be written in a high-level programming language such as C, C++, C#, Smalltalk, Java, JavaScript, Visual Basic, structured query language (for example, Transact-SQL), Perl, or written in various other programming languages.

[0097] It should be understood that each part of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0098] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0099] The above embodiments are only for illustrating the technical concept and characteristics of the present invention, and their purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the essence of the content of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for establishing a parameter model of an electrode-skin contact surface, characterized in that: include: Establish the electrode-skin complex impedance formula: z(t)=a(t)+jb(t); A continuous exponential sweep current with an angular frequency of ω is applied to the stimulation electrode as an excitation signal. The excitation signal is applied to both ends of the electrode, and the voltage generated is: U(t)=z(t)e jωt ; The voltage and current signals between the electrodes are sampled synchronously. The physical signal only contains the real part and cannot reflect the imaginary part. Therefore, the actual voltage signals U(t) and I(t) are as follows: Obtain two carrier signals; Multiply the two carrier signals by the voltage signal to obtain the real and imaginary parts of the complex impedance:

2. The method for establishing a parameter model of an electrode-skin contact surface according to claim 1, characterized in that: Based on the electrode-skin complex impedance formula, the electrode-resistance complex impedance model is obtained: Among them, R1, R2, K, and β are used to fit the model parameters using complex impedance spectroscopy.

3. The method for establishing a parameter model of an electrode-skin contact surface according to claim 2, characterized in that: Based on the Cole-Cole theory, parameter fitting is performed to obtain the coordinates of the arc origin and radius after fitting:

4. The method for establishing a parameter model of an electrode-skin contact surface according to claim 3, characterized in that: The complex impedance spectrum is fitted into a circle using the least squares method. R1, R2 and β are calculated based on the center and radius of the circle and the intersection with the real axis. K is calculated based on the complex impedance spectrum.

5. The method for establishing a parameter model of an electrode-skin contact surface according to claim 1, characterized in that: After multiplying the two carrier signals with the voltage signal, the signal is passed through a low-pass filter with a cutoff frequency lower than 2 times the carrier frequency and a passband gain of 2.

6. The method for establishing a parameter model of an electrode-skin contact surface according to claim 1, characterized in that: The two carrier signals are:

7. The method for establishing a parameter model of an electrode-skin contact surface according to claim 6, characterized in that: One of the carrier signals Ci(t) is a current signal I(t), and another carrier signal Cq(t) can be obtained by performing Hilbert transform on Ci(t).

8. A method for measuring parameters of an electrode-skin contact surface, based on a parameter model established by the method for establishing a parameter model of an electrode-skin contact surface according to any one of claims 1 to 7, characterized in that: include: The electrodes were attached to the subject’s scalp and the electrical stimulation device was turned on; The electrical stimulation device outputs a current signal I(t) and measures the voltage U(t) across the electrodes in real time; The complex impedance at the current frequency is calculated by the amplitude and phase relationship of the measured voltage U(t) and current I(t); The values ​​of complex impedance at different frequencies are measured, and based on the parameter model established by the parameter model establishment method of the electrode-skin contact surface, a curve of impedance changing with frequency on the complex plane is depicted, namely, a complex impedance spectrum.

9. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the parameter model establishment method of the electrode-skin contact surface as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The storage medium stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are loaded and executed by the processor to implement the method for establishing a parameter model of the electrode-skin contact surface as described in any one of claims 1 to 7.

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