A parameter model establishment method and measurement method for electrode-skin contact surface

Abstract

The present invention discloses a method for establishing and measuring a parameter model of an electrode-skin interface. This method for establishing a parameter model of an electrode-skin interface is based on an equivalent circuit model of double-layer capacitance. Complex impedance spectroscopy describes information about resistance (real part) and reactance (imaginary part) at different frequencies. This information can be used to fit the parameters of components in the model. Furthermore, when biological cells are placed in an AC electric field, the cells' dielectric response exhibits 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 electrode-tissue interface characteristics. The present invention relates to neuromodulation technology.

Description

Technical Field

[0001] The present invention relates to a nerve regulation technology, and in particular to a parameter model establishment method and a measurement method for an electrode-skin contact surface. Background Art

[0002] Transcranial electrical stimulation (tES) is a technique that uses low-intensity current to noninvasively modulate cortical neural activity. This regulation is achieved by adjusting the stimulation location, current intensity, and waveform. It has been widely used in the treatment of neuropsychiatric disorders, rehabilitation of brain damage, and cognitive function regulation. TESC devices use electrodes that adhere to the scalp to transmit the stimulation current. A conductive medium (such as conductive paste, conductive gel, or saline solution) is typically placed between the electrodes and the skin to reduce contact impedance.

[0003] During electrical stimulation, skin damage is easily caused, and the mechanism of damage is currently unclear. The occurrence of skin damage is related to multiple 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 it comes at the cost of reducing the stimulation intensity in the target area, which is not the optimal option 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 electrode-tissue contact resistance may reflect changes in skin condition or conductive medium.

[0004] Therefore, obtaining detailed electrode-skin interface parameters is helpful for accurately evaluating the electrode-skin contact condition and understanding the electrode-tissue characteristics, which can help reduce skin damage and promote electrode design. Summary of the Invention

[0005] In order to at least partially 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 the electrode-skin contact surface, which can accurately evaluate the electrode-skin contact condition and understand the electrode-tissue characteristics, thereby helping to reduce skin damage and promote 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 interface comprises the following steps:

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

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

[0010] 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:

[0011] U(t)=z(t)e jωt ;

[0012] 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:

[0013]

[0014] Obtain two carrier signals;

[0015] Multiply the two carrier signals with the voltage signal to obtain the real and imaginary parts 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] Among them, R1, R2, K, and β are model parameters fitted using complex impedance spectroscopy.

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

[0021]

[0022] According to some embodiments of the present application, 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, and K is calculated based on the complex impedance spectrum.

[0023] According to some embodiments of the present application, after multiplying the two carrier signals with the voltage signal, the signals are passed through a low-pass filter having a cutoff 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:

[0025]

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

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

[0028] A method for measuring parameters of an electrode-skin interface is provided, based on a parameter model established by the above-mentioned method for establishing a parameter model of an electrode-skin interface, and comprises the following steps:

[0029] The electrodes were attached to the subject's scalp and the electrical stimulation device was turned on;

[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 of the measured voltage U(t) and current I(t);

[0032] The complex impedance values ​​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 the complex impedance spectrum.

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

[0034] An 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, at least one program, the code set, or the instruction set is loaded and executed by the processor to implement the method for establishing a parameter model of the electrode-skin contact surface as described above.

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

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

[0037] The present invention has the following beneficial effects: Based on an equivalent circuit model of double-layer capacitance, the present invention describes information about resistance (real part) and reactance (imaginary part) at different frequencies through complex impedance spectroscopy, which can be used to fit the parameters of components in the model. Furthermore, when biological cells are placed in an AC electric field, the cells' dielectric response exhibits 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 embodiments of the present invention or the technical solutions in the prior art, the following introduction is made to the drawings of the embodiments of the present invention or the related technical solutions in the prior art. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative work.

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

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

[0041] Figure 3 It is a schematic diagram of the actual waveform of the swept current and swept voltage;

[0042] Figure 4 It is the curve of the real and imaginary parts of the complex impedance changing with frequency and the complex impedance spectrum;

[0043] Figure 5 It is a schematic diagram after fitting according to the Cole-Cole theory parameters. DETAILED DESCRIPTION

[0044] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and are not to be construed as limiting the present invention. The step numbers in the following embodiments are provided for ease of explanation only and do not limit the order of the steps. The order of execution of the steps 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 descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0046] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0047] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0048] Example 1

[0049] This embodiment provides a method for establishing a parameter model of the electrode-skin interface, and the establishment ideas are as follows:

[0050] When a metal electrode is placed in a physiological medium such as human tissue fluid, an interface forms between the two phases. In metal electrodes and circuit systems, charge is carried by electrons, whereas in physiological media, charge is carried by ions, including sodium, potassium, and chloride ions in extracellular fluid. When electrical stimulation is applied to tissue, charge carriers are transferred from electrons in the metal electrode to ions in the electrolyte. This process involves two electrochemical mechanisms: non-faradaic and faradaic reactions. In non-faradaic reactions, charge transfer does not involve a redox reaction of chemical species, but rather forms a double layer structure across the interface. The accumulation or diffusion of charge across the double layer transfers current, and the electrical properties of this process are very similar to those of a flat plate capacitor. Therefore, the capacitance at the electrode-electrolyte interface is often referred to as double-layer capacitance. In faradaic reactions, charge transfer is accompanied by a redox reaction of chemical species. This direct transfer of electrons from the electrode to ions in the solution follows Faraday's law, hence the name faradaic reaction.

[0051] At the actual electrode-tissue interface, these two reactions exist simultaneously, and the impedance model can be used as follows Figure 1 The equivalent circuit shown shows that 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 in series with the resistance R1 formed by the biological tissue and electrolyte. The model also includes the polarization voltage E formed by the electrode in the electrolyte solution.

[0052] Due to the electrochemical effect, the impedance characteristics of the double-layer capacitor differ from those of the ideal capacitor. Its impedance phase angle is approximately constant, so a constant phase element (CPE) is used instead. The impedance expression is as follows:

[0053]

[0054] The electrical stimulation devices currently on the market generally have impedance measurement functions, which can measure the equivalent resistance between electrodes. The measurement of equivalent resistance is affected by the excitation signal. The smaller the amplitude of the excitation signal, the higher the measured equivalent resistance. The devices from different manufacturers use different excitation signals, resulting in different measured resistances under the same contact conditions, making the impedance measurement values ​​between different devices incomparable.

[0055] In addition, the equivalent resistance reflects the characteristics of the electrode-skin contact surface to a certain extent. However, changes in the contact conditions between the electrode and the skin may manifest as changes in resistance and capacitance parameters, or as changes 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 by the equivalent resistance alone.

[0056] In order to provide a more detailed and stable description of the electrode-skin interface characteristics, the present invention is based on Figure 1 The equivalent circuit model shown in the figure proposes a parameter model establishment method to quantify the characteristics of the electrode-skin interface. Due to the presence of a capacitive device formed by a double electric layer, the whole presents a complex impedance. The complex impedance measurement circuit is as follows: Figure 2 As shown. The electrical stimulation device outputs a current signal I(t) of a specific frequency and measures the voltage U(t) across the electrode in real time. The complex impedance at the current frequency can be calculated through the amplitude and phase relationship of the voltage and current. By measuring the value of the complex impedance at different frequencies, a curve showing the impedance changing with frequency on the complex plane can be drawn, which is the complex impedance spectrum. The complex impedance spectrum describes the information of resistance (real part) and reactance (imaginary part) at different frequencies. This information can be used to fit the parameters of the components in the model. In addition, when biological cells are placed in an AC 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 viewed as the result of amplitude modulation of the current signal by complex impedance. According to the principle of orthogonal demodulation, when a complex signal amplitude modulates a carrier, the real and imaginary parts of the complex signal are modulated onto two orthogonal carriers, respectively. During demodulation, the received signal is demodulated using the same two orthogonal carriers as in the modulation process, thereby recovering the two components of the original signal. Therefore, by demodulating the voltage signal, the variation of the complex impedance over time can be obtained. If the carrier frequency is set as a function that varies with time, the variation of the complex impedance over time can be mapped into a curve showing the variation of the complex impedance with frequency, namely the complex impedance spectrum.

[0058] Based on the above ideas, the method for establishing a parameter model of the electrode-skin interface in the embodiment of the present application includes the following steps: S100. Establishing the electrode-skin complex impedance formula:

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

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

[0061] U(t)=z(t)e jωt ;

[0062] S300. Synchronously sample the voltage and current signals between the electrodes. 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:

[0063]

[0064] Sweep current and voltage waveform reference Figure 3 ;

[0065] S400. Obtain two carrier signals;

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

[0067]

[0068] Reference Figure 4 , Figure 4 (A) shows the curves of the real and imaginary parts of the complex impedance changing with frequency when the frequency changes from 3Hz to 100Hz. Figure 4 (B) in the figure is the corresponding complex impedance spectrum.

[0069] Furthermore, based on the electrode-skin complex impedance formula obtained above, the electrode-resistance complex impedance model is obtained:

[0070]

[0071] Among them, R1, R2, K, and β are model parameters fitted using complex impedance spectroscopy.

[0072] Furthermore, the presence of exponential and trigonometric functions in the model significantly increases the difficulty of parameter fitting. The Cole-Cole theory can simplify the calculation. 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 varies from zero to infinity, the complex impedance describes an arc. The coordinates of the arc's origin and radius after fitting are:

[0073]

[0074] The arc intersects the real axis at two points: (R1+R2,0) and (R1,0), corresponding to frequencies of 0 and infinity, respectively. The line connecting these intersections and the center of the circle makes an angle of πβ / 2 with respect to the imaginary axis. β lies between 0 and 1, and the lower β is, the lower the center of the circle is. When the frequency varies within a finite range, the measured complex impedance spectrum is a portion of a semicircle, with K determining the start and end points of the arc.

[0075] Furthermore, the least squares method is used to fit the complex impedance spectrum into a circle. According to the center and radius of the circle and the intersection with the real axis, R1, R2 and β are calculated, and K is calculated according to the complex impedance spectrum. At this point, the parameters of the electrode-skin equivalent circuit model can be obtained. The fitting results and parameters are as follows: Figure 5 Parameter R1 is negative because the actual electrode-skin interface cannot fully explain the measured data due to factors such as measurement level, frequency conditions, and model complexity. In particular, at higher frequencies, the impedance spectrum no longer represents a circular arc, resulting in negative fitting results. However, these parameters still reflect the characteristic differences of the electrode-skin interface and should be considered as characteristic parameters of the complex impedance spectrum.

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

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

[0078]

[0079] One of the carrier signals Ci(t) is the 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 interface, which is based on the parameter model established by the above-mentioned method for establishing a parameter model of an electrode-skin interface, and includes the following steps:

[0082] S600. Attach the electrodes to the subject's scalp 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 by the amplitude and phase relationship of the measured voltage U(t) and current I(t);

[0085] S900. Measure the complex impedance values ​​at different frequencies, and based on the parameter model established by the parameter model establishment method of the electrode-skin contact surface, draw a curve of impedance variation with frequency on the complex plane, i.e., a complex impedance spectrum.

[0086] Example 3

[0087] An embodiment of the present invention also provides an electronic device, comprising 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 above-mentioned method for establishing a parameter model of the electrode-skin contact surface.

[0088] It is understood that the memory may include random access memory (RAM) or read-only memory (ROM). Optionally, the memory includes a non-transitory computer-readable storage medium. The memory may 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, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function, instructions for implementing the various method embodiments described above, etc.; the data storage area may store data created based on the use of the server, etc.

[0089] The processor may include one or more processing cores. The processor utilizes various interfaces and circuits to connect various components within the server. It executes various server functions and processes data by running or executing instructions, programs, code sets, or instruction sets stored in memory, as well as accessing data stored in memory. Optionally, the processor may be implemented using at least one of the following hardware forms: digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor may integrate one or a combination of a central processing unit (CPU) and a modem. The CPU primarily processes the operating system and application programs, while the modem handles wireless communications. It is understood that the modem may not be integrated into the processor and may be implemented separately via a single chip.

[0090] Since the electronic device is an electronic device corresponding to a closed-loop transcranial electrical stimulation method of an embodiment of the present invention, and the principle of solving the problem by the electronic device is similar to that of the method, the implementation of the electronic device can refer to the implementation process of the above-mentioned method embodiment, and the repeated parts will not be repeated.

[0091] Example 4

[0092] An embodiment of the present invention also provides a computer-readable storage medium, which stores at least one instruction, at least one program, code set or instruction set. The at least one instruction, at least one program, code set or 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 skilled in the art will appreciate that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program. The program can be stored in a computer-readable storage medium, and the storage medium includes a read-only memory (ROM), a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium capable of carrying or storing data.

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

[0095] Example 5

[0096] In some possible implementations, various aspects of the methods of the embodiments of the present invention may also be implemented in the form of a program product, which includes program code. When the program product is executed on a computer device, the program code is used to cause the computer device to perform the steps of the method for establishing a parameter model of an electrode-skin interface according to various exemplary embodiments of the present application as described above in this specification. The executable computer program code or "code" used to perform the various embodiments may be written in a high-level programming language such as C, C++, C#, Smalltalk, Java, JavaScript, Visual Basic, Structured Query Language (e.g., Transact-SQL), Perl, or in various other programming languages.

[0097] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0098] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations 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 any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0099] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for establishing a parameter model of an electrode-skin interface, 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 with the voltage signal to obtain the real and imaginary parts of the complex impedance:

2. The method for establishing a parameter model of the electrode-skin interface according to claim 1, wherein: Based on the electrode-skin complex impedance formula, the electrode-resistance complex impedance model is obtained: Among them, R1, R2, K, and β are model parameters fitted using complex impedance spectroscopy.

3. The method for establishing a parameter model of the electrode-skin interface according to claim 2, wherein: Parameter fitting is performed based on the Cole-Cole theory to obtain the coordinates of the arc origin and radius after fitting:

4. The method for establishing a parameter model of the electrode-skin interface according to claim 3, wherein: The complex impedance spectrum is fitted to 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 then calculated based on the complex impedance spectrum.

5. The method for establishing a parameter model of the electrode-skin interface according to claim 1, wherein: 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 the electrode-skin interface according to claim 1, wherein: The two carrier signals are:

7. The method for establishing a parameter model of the electrode-skin interface according to claim 6, characterized in that: One of the carrier signals Ci(t) is the 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 interface, based on a parameter model established by the method for establishing a parameter model of an electrode-skin interface 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; Calculate the complex impedance at the current frequency through the amplitude and phase relationship of the measured voltage U(t) and current I(t); The complex impedance values ​​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 the 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 parameter model establishment method of the electrode-skin contact surface as described in any one of claims 1 to 7.

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