A skin impedance measurement method, system and bone conduction headset

Abstract

The present invention provides a skin impedance measurement method, system and bone conduction headset, including the following steps: Step S1. Generate an excitation signal U1 for exciting an external complex impedance, and transmit the excitation signal U1 to an electrode sheet in contact with the user's skin; Step S2. Collect the response signal U2 returned by the electrode sheet, perform gain amplification on the response signal U2 and then perform discrete Fourier transform processing to obtain the skin impedance Z of the response signal U2; Step S3. Calibrate the skin impedance Z with a gain coefficient G, where the gain coefficient G is obtained by looking up a mapping table, and this mapping is the correspondence between the measurement frequency corresponding to the collected response signal U2 and the set frequency, so as to obtain the calibrated skin impedance Z of the user. The present invention can quickly and accurately measure the skin permeability of the current user.

Description

Technical Field

[0001] The present invention relates to the technical field of skin impedance measurement methods, and mainly relates to a skin impedance measurement method, system and bone conduction headset. Background Art

[0002] With the rapid growth of China's economy and the continuous improvement of education level, people's health awareness has generally increased. The concept of prevention first and early detection and treatment of diseases has become a health concept widely accepted and pursued by the public. At the same time, with the development of intelligent mobile terminals and intelligent wearable devices, their functions have become more complete. Various applications related to mobile terminals and intelligent wearable devices also cover all aspects of life. Skin impedance can be used as a characterization of skin permeability. Therefore, by measuring skin impedance, the current skin permeability of users can be understood, providing a basis for human physiological detection. There is a publicly disclosed measurement device and method for the contact impedance between an electrode and the skin, such as the one with the application number CN201610993529. However, this skin impedance measurement method takes a relatively long time to collect, generally with an evaluation time greater than two hours, and the accuracy of the measured skin impedance is not high, resulting in the inability to quickly and accurately measure the current skin permeability of users.

[0003] Existing methods can obtain the calibrated impedance value by multiplying the gain coefficient and the impedance value, but the gain coefficient is not compensated, which is likely to cause the calibrated impedance value not to match the current impedance value of the user's skin, and the accuracy of the calibrated impedance value cannot be improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a skin impedance measurement method, system and bone conduction headset, which can accurately measure the current skin permeability of users.

[0005] To this end, a skin impedance measurement method is provided, including the following steps:

[0006] Step S1. Generate an excitation signal U1 for exciting an external complex impedance, and transmit the excitation signal U1 to an electrode sheet in contact with the user's skin;

[0007] Step S2. Collect the response signal U2 returned by the electrode sheet, perform gain amplification on the response signal U2 and then perform discrete Fourier transform processing to obtain the skin impedance Z of the response signal U2;

[0008] Step S3. Calibrate the skin impedance Z with a gain coefficient G, where the gain coefficient G is obtained by looking up a mapping table, and this mapping is the corresponding relationship between the measurement frequency corresponding to the collected response signal U2 and the set frequency, so as to obtain the calibrated skin impedance Z of the user.

[0009] Further, the specific operation of step S2 is as follows: Different external clocks are introduced to switch different measurement ranges within the low-frequency band, and it is checked whether the current measurement frequency is within the set range. If so, the polarity of the acquired response signal U2 is swept and step S3 is entered; otherwise, the measurement range is switched until the current measurement frequency is within the set range.

[0010] Further, step S2 also includes: Switching different measurement ranges within the low-frequency band and collecting the response signal U2, where the measurement range is 1 kΩ to 10 MΩ.

[0011] Further, step S3 also includes: Before the response signal U2 undergoes discrete Fourier transform processing, it is first subjected to gain amplification and filtering processing.

[0012] Further, the specific operation of step S3 is as follows: Each frequency point in the response signal U2 is separately subjected to discrete Fourier transform processing to obtain the real part R and imaginary part I data corresponding to each frequency point, and the amplitude A and phase θ of the skin impedance Z are calculated based on the real part R and imaginary part I data.

[0013] Further, the real part R and imaginary part I data are put into the following algorithm for separate operations to obtain the amplitude A and phase θ of the skin impedance Z:

[0014]

[0015] Further, the skin impedance Z is the reciprocal of the product of the amplitude A and the gain coefficient G, and the specific algorithm is as follows:

[0016] Z = 1 / AG.

[0017] Further, by adding different feedback resistors R f to switch different measurement ranges within the low-frequency band, the corresponding feedback resistor R f is substituted into the following algorithm to calculate the gain coefficient G:

[0018]

[0019] Further, it also includes a step of verifying the gain coefficient G, and the specific operation of this verification step is as follows:

[0020] Step a. For each external clock used, the measurement frequency corresponding to this external clock is divided into multiple frequency bands;

[0021] Step b. A known calibration resistor and capacitor are respectively connected to both ends of the electrode plate, and the corresponding feedback resistor R f is selected, and the feedback resistor R f is connected to the connection end for collecting the response signal U2, and the gain coefficient G of each frequency point is calculated through operation;

[0022] Step c. The gain coefficient G for each frequency point is calculated by sweeping the frequency, and the gain coefficient G for each frequency point after the frequency sweep calculation is stored.

[0023] A system includes a controller, a digital frequency synthesizer, a complex impedance measurement module, an analog switch, and electrode pads that are electrically connected to the controller respectively. The electrode pads are connected to the complex impedance measurement module and the analog switch respectively. The electrode pads are used to contact the user's skin. The analog switch is used to transmit the excitation signal U1. The complex impedance measurement module collects the response signal U2. The digital frequency synthesizer is connected to the complex impedance measurement module and is used to adjust the acquisition frequency of the complex impedance measurement module.

[0024] And it includes a memory arranged to store computer-executable instructions, and the executable instructions, when executed, cause the controller to implement the skin impedance measurement method as described above.

[0025] Further, the digital frequency synthesizer includes the chip AD9833 and its peripheral system, and the chip AD9833 is connected to the controller through a bus.

[0026] Further, the complex impedance measurement module is specifically a complex impedance chip and its peripheral system connected through a bus.

[0027] Further, the electrode pads include a gold interdigitated electrode layer, an insulating layer, and a shielding layer stacked in sequence, and the gold interdigitated electrode layer is used to fit the user's skin.

[0028] Further, the analog switch is specifically the chip AD4066 and its peripheral system, and also includes more than one feedback resistor, which are respectively arranged on the connection lines between the chip AD4066 and the controller.

[0029] A bone conduction headset includes a bone conduction headset housing and a bone conduction oscillator housing. The bone conduction headset housing includes the system as described above. The bone conduction oscillator in the bone conduction oscillator housing is electrically connected to the controller. The system is all arranged in the bone conduction headset housing. The electrode pads are arranged on the side wall of the bone conduction headset housing. When the user wears the bone conduction headset, the electrode pads are in close contact with the user's skin.

[0030] Beneficial effects:

[0031] The skin impedance measurement method of the present invention generates an excitation signal U1 for exciting an external complex impedance, transmits the excitation signal U1 to an electrode patch in contact with the user's skin, controls the measurement frequency to be in the low-frequency band to collect the response signal U2 returned by the electrode patch, performs discrete Fourier transform processing on each frequency point in the filtered response signal U2 to obtain the skin impedance value of each frequency point in the response signal U2. This skin impedance value corresponds to the skin permeability of the user. According to multiple experiments, it is found that the measurement frequency in the low-frequency range can accurately measure the skin impedance. At the same time, a compensation calculation is performed on the gain coefficient, and the compensated gain coefficient is used to calibrate the skin impedance value, that is, the skin permeability of the user can be accurately measured. And the accurate skin permeability can be used to more finely evaluate the penetration ability of the skin, providing guidance for applications such as transdermal drug delivery and extraction of tissue fluid target substances.

[0032] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented in accordance with the content of the description. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specifically illustrates the specific embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0034] Figure 1 is the structural block diagram of the skin impedance measurement system in the present invention;

[0035] Figure 2 is the schematic diagram of the principle of the proportional measurement method of the complex impedance based on AD5933;

[0036] Figure 3 is the capacitive load impedance and phase diagram measured by the system in the present invention from 10 Hz to 100 kHz;

[0037] Figure 4 is the schematic diagram of the comparison of skin impedance and phase before and after the penetration enhancement effect in the skin impedance measurement system of the present invention;

[0038] Figure 5 is the schematic diagram of the specific operation process of the system;

[0039] Figure 6 is the structural schematic diagram of the electronic device of the present invention;

[0040] Figure 7 is the structural schematic diagram of the computer-readable storage medium of the present invention.

[0041] Description of the accompanying drawings: 21 - processor; 22 - memory; 23 - storage space; 24 - program code; 31 - program code. DETAILED DESCRIPTION

[0042] The present invention is further described in conjunction with the following examples.

[0043] See Figure 1 , the skin impedance measurement method in this embodiment,

[0044] Step S1. Generate an excitation signal U1 for exciting an external complex impedance, and transmit the excitation signal U1 to an electrode sheet in contact with the user's skin;

[0045] Step S2. Collect the response signal U2 transmitted back by the electrode sheet, perform discrete Fourier transform processing on the response signal U2 after gain amplification, and obtain the skin impedance Z of the response signal U2;

[0046] Step S3. Use the gain coefficient G to calibrate the skin impedance Z. The gain coefficient G is obtained by looking up a mapping table. The mapping is the correspondence between the measurement frequency corresponding to the collected response signal U2 and the set frequency, thereby obtaining the calibrated skin impedance Z of the user.

[0047] Furthermore, the step S2 is specifically as follows: by passing different external clocks to realize switching of different measurement ranges in the low frequency band, and checking whether the current measurement frequency is within the set range. If so, the polarity of the collected response signal U2 is scanned and step S3 is entered; otherwise, the measurement range is switched to the current measurement frequency within the set range.

[0048] Furthermore, the step S2 also includes: switching different measurement ranges in the low frequency band and collecting the response signal U2, wherein the measurement range is 1 kΩ to 10 MΩ.

[0049] Furthermore, the step S3 also includes: before the discrete Fourier transform processing is performed on the response signal U2, it is first subjected to gain amplification and filtering processing.

[0050] Furthermore, the step S3 is specifically as follows: performing discrete Fourier transform processing on each frequency point in the response signal U2 to obtain the real part R and imaginary part I data corresponding to each frequency point, and calculating the amplitude A and phase θ of the skin impedance Z according to the real part R and imaginary part I data.

[0051] Furthermore, the real part R and imaginary part I data are put into the following algorithm to calculate the amplitude A and phase θ of the skin impedance Z respectively:

[0052]

[0053] Further, the skin impedance Z is the reciprocal of the product of the amplitude A and the gain coefficient G, and the specific algorithm is as follows:

[0054] Z = 1 / AG.

[0055] Further, by adding different feedback resistors R f to switch different measurement ranges within the low-frequency band, substitute the corresponding feedback resistor R f into the following algorithm to obtain the gain coefficient G:

[0056]

[0057] Further, it also includes a step of verifying the gain coefficient G, and the specific verification step is as follows:

[0058] Step a. For each external clock used, divide the measurement frequency corresponding to the external clock into multiple frequency bands;

[0059] Step b. Connect known calibration resistors and capacitors to both ends of the electrode plate respectively, select the corresponding feedback resistor R f , and connect the feedback resistor R f to the connection terminal for collecting the response signal U2, and calculate to obtain the gain coefficient G at each frequency point;

[0060] Step c. Perform sweep frequency calculations on the gain coefficient G at each frequency point respectively, and store the gain coefficient G at each frequency point after the sweep frequency calculation.

[0061] A system includes a controller, a digital frequency synthesizer, a complex impedance measurement module, an analog switch, and electrode plates that are electrically connected to the controller respectively. The electrode plates are connected to the complex impedance measurement module and the analog switch respectively. The electrode plates are used to contact the skin of the user. The analog switch is used to transmit the excitation signal U1. The complex impedance measurement module collects the response signal U2. The digital frequency synthesizer is connected to the complex impedance measurement module and is used to adjust the acquisition frequency of the complex impedance measurement module,

[0062] and includes a memory arranged to store computer-executable instructions, and the executable instructions, when executed, cause the controller to implement the skin impedance measurement method as described above.

[0063] Further, the digital frequency synthesizer includes the chip AD9833 and its peripheral system, and the chip AD9833 is connected to the controller through a bus.

[0064] Further, the complex impedance measurement module is specifically a complex impedance chip and its peripheral system connected through a bus.

[0065] Further, the electrode sheet includes a gold interdigital electrode layer, an insulating layer, and a shielding layer stacked in sequence, and the gold interdigital electrode layer is used to fit against the user's skin.

[0066] Further, the analog switch is specifically the chip AD4066 and its peripheral system, and further includes at least one feedback resistor, which are respectively arranged on the connection lines between the chip AD4066 and the controller.

[0067] Further, the controller in this application can be a 32-bit single-chip microcomputer. Using a low-cost single-chip microcomputer can accurately measure skin impedance, which can further reduce the production cost of enterprises.

[0068] A bone conduction earphone includes a bone conduction earphone housing and a bone conduction oscillator housing. The bone conduction earphone housing includes the system as described above. The bone conduction oscillator in the bone conduction oscillator housing is electrically connected to the controller. The system is arranged in the bone conduction earphone housing, and the electrode sheet is arranged on the side wall of the bone conduction earphone housing. When the user wears the bone conduction earphone, the electrode sheet closely adheres to the user's skin.

[0069] The specific working process and principle are as follows:

[0070] I. Measurement principle of skin impedance Z

[0071] Let the excitation signal U1 = U 1m ×sinωt, I = U1×S1,

[0072] Then the response signal U2 = -I×R f = -U 1m ×R f ×S×sin(ωt + j), where j is the phase of the measured conductance, S is the amplitude of the measured conductance, and Rf is the reference resistor. As long as U2 and U1 are compared, the information of the impedance to be measured can be obtained. The measurement accuracy is independent of the power supply voltage error and only related to the accuracy of the reference resistor.

[0073] See Figure 2 , the signal generated by a direct digital synthesizer (DDS) excites an external complex impedance. The response signal is amplified by a programmable gain amplifier (PGA), and after passing through a low-pass filter, it is sampled by a 12-bit ADC and then processed by a discrete Fourier transform (DFT) to obtain the real part (R) and imaginary part (I) data. Excitation signal. The amplitude A and phase θ of the impedance are calculated using formulas (2) and (3).

[0074]

[0075] II. Based on the above principle, the present invention provides the following system:

[0076] 1. Hardware design

[0077] Figure 1 is the structural block diagram of the skin impedance measurement system in this embodiment, including a digital frequency synthesizer system composed of a DDS chip (AD9833), a complex impedance measurement system composed of a complex impedance chip (AD5933), and an analog switch network composed of CD4066. The DDS is used to generate the clock source required by the complex impedance chip, and is sent to the CLK terminal of the AD5933 through the drive system as the external clock. In order to accurately analyze the low-frequency impedance, it is necessary to reduce the clock frequency of the AD5933, thereby reducing the sampling rate of the ADC and making the single-point DFT meet the required 1024 sampling points. Table 1 shows the corresponding relationship between the measurement frequency and the external frequency of the AD5933.

[0078] Table 1 Corresponding relationship between measurement frequency and external frequency

[0079]

[0080] The main control chip communicates with the AD5933 through the I2C interface to read the real part and the imaginary part corresponding to each frequency point. In order to measure the impedance of the skin in a wide range, different feedback resistors need to be connected for range switching. The analog switch CD4046 has 4 channels to switch different ranges, and selects the appropriate feedback resistor to make the measurement range reach 1 kΩ to 10 MΩ, meeting the measurement range requirements of the skin impedance.

[0081] The electrode patch includes a copper shielding electrode, an insulating layer, and interdigital electrodes stacked in sequence.

[0082] The copper shielding electrode, the area of the shielding electrode should completely cover the area corresponding to the interdigital electrodes to reduce external interference.

[0083] The insulating layer can be made of polyimide material.

[0084] The interdigital electrodes are integrated on the main board bin of the bone conduction earphone. After assembly, when the user wears it, the interdigital electrode surface fits the human skin, so as to measure the skin impedance.

[0085] 2. Software design

[0086] 2.1 Impedance calculation

[0087] The DFT transformation obtains the real part and the imaginary part of a single frequency point, and then calculates the amplitude of this frequency point through formula (2). In order to convert the amplitude into impedance, it is necessary to multiply by the gain (G) coefficient.

[0088] Z = 1 / AG (2)

[0089] The gain coefficient is calculated by connecting a known standard impedance. Table 2 lists the corresponding relationships between the feedback resistors and calibration resistors under different measurement ranges. Connect the known standard impedance to the test terminal and select the corresponding feedback resistor Rf to obtain the gain coefficient at this frequency point.

[0090]

[0091] Table 2 Feedback Resistors and Calibration Resistors Used under Different Measurement Ranges

[0092]

[0093] To ensure the accuracy of impedance compensation, it is necessary to combine the mapping relationships in Table 1 and Table 2 to obtain the gain coefficient G. This mapping is the corresponding relationship between the measured frequency corresponding to the acquired response signal U2 and the set frequency, and then the compensation for the gain coefficient G is achieved to improve the acquisition accuracy. Under different external clocks, the frequency is divided into multiple frequency bands, and the gain coefficients at each frequency point are calculated by sweeping the frequency respectively and stored in an array.

[0094] 2.2 Phase Calculation

[0095] 1. Amplitude-Frequency and Phase-Frequency Scanning

[0096] Connect a resistor R = 4.7 KΩ and a capacitor C = 1 nF in series across the electrodes, as shown in Figure 3 , the amplitude-frequency and phase-frequency characteristic curves under the frequency condition of 10 Hz to 10 kHz, Figure 3 can reflect the capacitive load impedance and phase diagram measured by this system from 10 Hz to 100 kHz. In the figure, the capacitive impedance decreases with the increase of frequency, and the phase is between -90° and 0°, indicating that the system can measure the capacitive impedance.

[0097] The phase of the response signal calculated using Equation (4) consists of two parts: the system phase and the phase generated by the unknown impedance. Therefore, to calculate the phase, the system phase φsystem needs to be subtracted from the phase φunknown calculated from the impedance of the capacitive system.

[0098]

[0099] The excitation signal of the capacitive impedance leads the response signal by 90°. Therefore, there is a phase difference of approximately -90° between the resistive system phase and the capacitive system phase. The skin impedance consists of multiple RC networks, so its phase is between -90° and 0°. The sign of the phase angle is determined by the signs of the real part and the imaginary part. In the measurement of complex impedance, the phase angle is converted to the corresponding interval according to the signs of the real part and the imaginary part.

[0100] 2. Skin Amplitude-Frequency and Phase-Frequency Scanning

[0101] The low-frequency impedance of human skin can better reflect its permeability. The commonly used measurement frequencies are 100 Hz and 1 kHz. The frequency range used in this experiment is 10 Hz to 10 kHz, including these two frequency endpoints. At room temperature of 32 °C and humidity of 40% RH, the electroporation-enhanced permeation method is used to promote the skin permeation, as shown in Figure 4 , which is a schematic diagram of the comparison of skin impedance and phase before and after the permeation enhancement, comparing the changes before and after the permeation enhancement.

[0102] It can be seen from Figure 4 that after the skin undergoes the electroporation-enhanced permeation, its impedance decreases, and the impedance becomes more capacitive, indicating that the water-soluble channels of the skin are opened and the permeation ability is improved.

[0103] 2.3 Software Process Design

[0104] The software process of the system is as shown in Figure 5 . When performing frequency scanning, first program the scanning parameters into the corresponding registers, including the starting frequency, increment number, and frequency increment. Then read and calculate the measurement parameters, judge whether they meet the range, switch the analog electronic switch to the corresponding gear, then resend the initialization command, and after a certain time, send a start frequency scanning command to the control register, poll the status register to detect whether the DFT is completed, read the values of the corresponding registers, and calculate in combination with the impedance coefficient and phase coefficient.

[0105] III. Conclusion

[0106] The system is used to test the permeation ability of the electroporation-promoted skin. The results show that the system can be used to evaluate the skin permeation ability. Therefore, the system can be applied to distinguish the skin permeation abilities of different individuals, providing a basis for adjusting the parameters of wearable devices related to the physiological and biochemical detection of human tissue fluid, thereby reducing the occurrence of individual skin allergies and other harmful phenomena while ensuring work efficiency.

[0107] It should be noted that:

[0108] The method used in this embodiment can be transformed into program steps and devices that can be stored in a computer storage medium and implemented by being called and executed by a slave controller.

[0109] The algorithms and displays provided here are not inherently related to any specific computer, virtual device, or other equipment. The description made for a specific language is to disclose the best implementation mode of the present invention.

[0110] In the description provided herein, numerous specific details are set forth. It will be understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0111] Similarly, it should be understood that in order to streamline this disclosure and assist in understanding one or more of the various inventive aspects, in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, the disclosed method should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, the inventive aspects lie in less than all the features of the single foregoing disclosed embodiment, as reflected in the claims. Thus, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the invention.

[0112] Those skilled in the art will appreciate that the modules in the devices in the embodiments can be adaptively changed and disposed in one or more devices different from those of the embodiments. The modules or units or components in the embodiments can be combined into one module or unit or component, and in addition, they can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all the features disclosed in this specification (including the accompanying claims, abstract and drawings) and all the processes or units of any method or device so disclosed. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) can be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0113] In addition, those skilled in the art will be able to understand that although some of the embodiments described herein include certain features included in other embodiments but not others, the combination of features of different embodiments means that it is within the scope of the invention and forms different embodiments.

[0114] Each component embodiment of the present invention can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) can be used in practice to implement some or all of the functions of some or all of the components in the device for detecting the wearing state of the electronic device according to the embodiments of the present invention. The present invention can also be implemented as a device or device program (such as a computer program and a computer program product) for executing part or all of the methods described herein. Such a program implementing the present invention can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0115] For example, Figure 6 The structural schematic diagram of an electronic device according to an embodiment of the present invention is shown. Traditionally, the electronic device includes a processor 21 and a memory 22 arranged to store computer-executable instructions (program code). The memory 22 can be an electronic memory such as flash memory, EEPROM (electrically erasable programmable read-only memory), EPROM, hard disk, or ROM. The memory 22 has a storage space 23 for storing program code 24 for executing any method step in the embodiment. For example, the storage space 23 for the program code can include respective program codes 24 for implementing various steps in the above method. These program codes can be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, compact discs (CDs), memory cards, or floppy disks. Such computer program products are usually, for example Figure 7 the computer-readable storage media described above. The computer-readable storage media can have storage segments, storage spaces, etc. arranged similarly to the memory 22 in the Figure 6 electronic device. The program code can be compressed in an appropriate form, for example. Generally, the storage unit stores program code 31 for executing the method steps according to the present invention, that is, program code that can be read by a processor such as 21. When these program codes are run by the electronic device, the electronic device is caused to execute each step in the method described above.

[0116] It should be noted that the above embodiments are illustrative of the present invention and not restrictive thereof, and alternative embodiments can be designed by those skilled in the art without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present invention can be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In the unit claims listing several devices, several of these devices can be embodied by the same item of hardware. The use of the words first, second, and third, etc. does not denote any order. These words can be interpreted as names.

Claims

1. A skin impedance measurement method, characterized in that, Including the following steps: Step S1. Generate an excitation signal U1 for exciting an external complex impedance, and transmit the excitation signal U1 to an electrode patch in contact with the user's skin; Step S2. Collect the response signal U2 transmitted back by the electrode patch, perform gain amplification on the response signal U2 and then perform discrete Fourier transform processing to obtain the skin impedance Z of the response signal U2; Step S3. Calibrate the skin impedance Z with a gain coefficient G, where the gain coefficient G is obtained by looking up a mapping table, and this mapping is the corresponding relationship between the measurement frequency corresponding to the collected response signal U2 and the set frequency, so as to obtain the calibrated skin impedance Z of the user; The specific content of step S2 is: by accessing different external clocks, different measurement ranges are switched within the low-frequency band, and it is detected whether the current measurement frequency is within the set range. If so, the collected response signal U2 is swept and step S3 is entered; otherwise, the measurement range is switched until the current measurement frequency is within the set range; The specific content of step S3 is: perform discrete Fourier transform processing on each frequency point in the response signal U2 to obtain the real part R and imaginary part I data corresponding to each frequency point, and calculate the amplitude A and phase θ of the skin impedance Z according to the real part R and imaginary part I data; Put the real part R and imaginary part I data into the following algorithm to calculate the amplitude A and phase θ of the skin impedance Z respectively: ， ； The skin impedance Z is the reciprocal of the product of the amplitude A and the gain coefficient G, and the specific algorithm is as follows: ； By increasing different feedback resistors to achieve switching of different measurement ranges within the low-frequency band, substitute the corresponding feedback resistors into the following algorithm to obtain the gain coefficient G: 。 2. The skin impedance measurement method according to claim 1, characterized in that, Step S3 further includes: before the response signal U2 is subjected to discrete Fourier transform processing, it is first filtered.

3. The skin impedance measurement method according to claim 1, wherein There is also a step of verifying the gain coefficient G, and the specific content of this verification step is: Step a. For each external clock used, divide the measurement frequency corresponding to this external clock into multiple frequency bands; Step b. Connect the known calibration resistor to the electrode sheet and select the corresponding feedback resistor , and connect the feedback resistor to the connection terminal for collecting the response signal U2, and calculate the gain coefficient G at each frequency point Step c. Perform sweep frequency calculations on the gain coefficient G of each frequency point respectively, and store the gain coefficient G of each frequency point after the sweep frequency calculation.

4. A system for skin impedance measurement, characterized in that, It includes a controller and a digital frequency synthesizer, a complex impedance measurement module, an analog switch, and an electrode patch that are electrically connected to the controller respectively. The electrode patch is connected to the complex impedance measurement module and the analog switch respectively. The electrode patch is used to contact the user's skin. The analog switch is used to transmit the excitation signal U1. The complex impedance measurement module collects the response signal U2. The digital frequency synthesizer is connected to the complex impedance measurement module and is used to adjust the acquisition frequency of the complex impedance measurement module. And it includes a memory arranged to store computer-executable instructions, and is characterized in that when the executable instructions are executed, the controller implements the skin impedance measurement method according to any one of claims 1 to 3.

5. A bone conduction headset, comprising a bone conduction headset housing and a bone conduction oscillator housing, characterized in that, The bone conduction headphone housing includes the system according to claim 4. The bone conduction oscillator in the bone conduction oscillator housing is electrically connected to the controller. The system is arranged in the bone conduction headphone housing. The electrode patch is arranged on the side wall of the bone conduction headphone housing. When the user wears the bone conduction headphones, the electrode patch is in close contact with the user's skin.

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