A method for quantitatively measuring the impedance of skin

Abstract

The application discloses a method for quantitatively measuring skin impedance, and the method comprises the following steps: obtaining a measurement site; placing an electrode group formed by four silver chloride electrodes on the measurement site by using a four-electrode constant-current impedance measurement device, and measuring impedance values under different current sizes and frequencies; generating a scatter plot of impedance values changing with current or frequency according to the measurement results; fitting the scatter plot, determining fitting parameters, and obtaining parameters for describing impedance characteristics of the measurement site at the point. The application quantifies the linearity and size of the skin impedance, obtains new evaluation parameters, quantitatively evaluates the non-linear skin impedance characteristics, and is used for application scenarios related to impedance analysis, thereby improving the technical level of instrument development based on biological impedance technology, such as clinical monitoring and diagnosis, and helping meridian essence research.

Description

Technical Field

[0001] This invention relates to the field of bioimpedance research, and more specifically to a method for quantitatively measuring skin impedance. Background Technology

[0002] Bioimpedance studies the electrical properties of biological tissues and organs, reflecting human physiological and pathological conditions. In the field of sports, bioimpedance can assess body composition and water content, helping athletes and coaches design personalized training programs. In the medical field, electrical impedance tomography (EIT) and impedance-based meridian function evaluation instruments (such as meridian meters) are widely used clinically. Skin impedance is a type of bioimpedance that measures the impedance of tissues near the body surface and has been used to describe the electrical properties of acupoints and meridians. There are different methods for measuring skin impedance or meridian impedance. Common methods include the two-electrode method and the four-electrode method. The two-electrode method, because it acts on the skin surface, is affected by the condition of the skin, electrode wettability, pressure, and duration of skin contact, and the electrodes themselves can irritate the skin, resulting in relatively poor reproducibility. The four-electrode method places a pair of excitation electrodes on the outside of the test site, applies a constant current, and places a pair of measuring electrodes on the test point, measuring the voltage between the test points, and then using Ohm's law to calculate the impedance at the test location. The four-electrode method minimizes the influence of electrode-skin impedance, resulting in greater accuracy. However, regardless of whether a two-electrode or four-electrode method is used, the detected impedance value is closely related to the frequency. Biological tissues possess resistive, capacitive, and inductive properties; as the frequency increases, the capacitive reactance decreases, and the total impedance drops when the frequency exceeds 10kHz. Therefore, it is essential to clearly define the measurement frequency when evaluating impedance.

[0003] Furthermore, skin impedance or meridian impedance exhibits a nonlinear response to current, meaning the magnitude of skin impedance varies with the magnitude of the current passing through the measurement location. This leads to inconsistent impedance values ​​obtained under different measurement conditions, a significant reason for discrepancies in results from different research groups. As early as 1979, researchers reported nonlinear characteristics of acupoint resistance (Fraden J, Galman S. Investigation of nonlinear effects in surface electroacupuncture. Am J Acupunct, 1979, 7:21). Many years later, scholars have made some progress in researching the nonlinear characteristics of acupoints (Wei Jianzi, Shen Xueyong. Nonlinear characteristics and applications of acupoint resistance. Chinese Acupuncture, 2023, 43:4.). In their research, Wei Jianzi et al. proposed that the volt-ampere curve of acupoints resembles a parabola, exhibiting significant nonlinear characteristics. Therefore, existing linear detection methods (i.e., inputting a fixed current / voltage to the acupoint, detecting the response voltage / current value, and then calculating the resistance value of the acupoint according to Ohm's law) cannot accurately reflect the resistance characteristics of acupoints. The electrical characteristics of acupoints should be characterized by their volt-ampere curves, for example, by using the area between the volt-ampere curve and the current axis to estimate the impedance value (Wei JZ et al. Research on Nonlinear Feature of Electrical Resistance of Acupuncture Points. Evidence-Based Complementary and Alternative Medicine. 2012, 179657). However, simply using the area of ​​the volt-ampere curve loses the dynamic information of the curve and cannot reflect the linear characteristics of impedance changes. To better describe the electrical characteristics of acupoints and meridians, it is necessary to quantify the linearity and magnitude of skin impedance.

[0004] Given that skin impedance or meridian impedance has nonlinear characteristics in response to current, in order to ensure the comparability of impedance values ​​obtained under different measurement conditions and the accuracy of the results, it is necessary to quantitatively analyze the nonlinear characteristics of biological impedance and obtain characteristic parameters that can reflect the impedance of the site. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a method for quantitatively measuring skin impedance, which solves the problem that existing methods result in inconsistent impedance values ​​under different measurement conditions, making it impossible to guarantee the accuracy of the results.

[0006] According to a first aspect, embodiments of the present invention provide a method for quantitatively measuring skin impedance, comprising:

[0007] Obtain the test data for the part to be tested;

[0008] The impedance values ​​are determined based on the test data under different current magnitudes and frequencies, and the impedance values ​​are measured through an electrode assembly formed by four silver chloride electrodes.

[0009] Based on the measured impedance value, a scatter plot of the impedance value as a function of current or frequency is generated.

[0010] The scatter plot is fitted to determine the fitting parameters, and then the parameters of the impedance characteristics corresponding to the data to be measured are determined.

[0011] The method for quantitatively measuring skin impedance provided in this invention obtains new evaluation parameters by quantifying the linearity and magnitude of skin impedance. These parameters are used to quantitatively evaluate nonlinear skin impedance characteristics and can be applied to impedance analysis-related scenarios. On the one hand, this improves the technical level of instrument development for clinical monitoring and diagnosis based on bioimpedance technology; on the other hand, it can contribute to the study of the essence of meridians.

[0012] In conjunction with the first aspect, in the first embodiment of the first aspect, the step of measuring the impedance value under different current magnitudes and frequencies based on the test data, wherein the impedance value is measured through an electrode assembly formed by four silver chloride electrodes, includes:

[0013] The electrode group is configured using four-electrode technology;

[0014] The impedance values ​​at different currents at a preset frequency are measured using the electrode assembly.

[0015] In conjunction with the first embodiment of the first aspect, in the second embodiment of the first aspect, generating a scatter plot of impedance value as a function of current or frequency based on the measured impedance value includes:

[0016] A scatter plot is generated using the current and the measured impedance value.

[0017] In conjunction with the second embodiment of the first aspect, in the third embodiment of the first aspect, the step of fitting the scatter plot and determining the fitting parameters includes:

[0018] The fitting equation is determined based on the impedance value and the current in the scatter plot, thereby determining the fitting parameters;

[0019] The fitting equation is expressed as follows:

[0020] Impedance value = a * e b / current ,

[0021] Where a is the estimated maximum impedance value; b is the linearity coefficient, which indicates the degree to which the impedance value is affected by the current; and current represents the current.

[0022] In conjunction with the second embodiment of the first aspect, in the fourth embodiment of the first aspect, the fitting equation can also be expressed as follows:

[0023] Impedance value = a + b / current

[0024] Where a is the estimated maximum impedance value; b is the linearity coefficient, which indicates the degree to which the impedance value is affected by the current; and current represents the current.

[0025] In conjunction with the first aspect, in the fifth embodiment of the first aspect, the method is applied to body composition analysis by skin impedance measurement, including evaluation of water content, fat content and muscle mass.

[0026] In conjunction with the first aspect, in the sixth embodiment of the first aspect, the method is also applied to body meridian impedance analysis and the derived meridian function evaluation. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a flowchart of a method for quantitatively measuring skin impedance according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of three meridian lines and the two middle lines according to a preferred embodiment of the present invention, as well as the electrode device used.

[0030] Figure 3 This is a schematic diagram of the electrode assembly placed at the test site according to a preferred embodiment of the present invention;

[0031] Figure 4 This is a framework diagram of impedance measurement using a four-electrode technique according to a preferred embodiment of the present invention.

[0032] Figure 5 This is a graph showing the impedance value as a function of frequency under different excitation currents according to a preferred embodiment of the present invention;

[0033] Figure 6 This is a graph showing the impedance value as a function of excitation current at different frequencies according to a preferred embodiment of the present invention.

[0034] Figure 7 This is a scatter plot and its fitted curve showing the impedance value as a function of excitation current according to a preferred embodiment of the present invention;

[0035] Figure 8 It is a linear fitting curve graph achieved by data transformation according to a preferred embodiment of the present invention;

[0036] Figure 9 This is a schematic diagram of the impedance measured in the three yin meridians of the arm and the middle region according to a preferred embodiment of the present invention;

[0037] Figure 10 This is a schematic diagram of the functional modules of a device for quantitatively measuring skin impedance according to an embodiment of the present invention;

[0038] Figure 11 This is a schematic diagram of the hardware structure of the electronic device provided in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This embodiment provides a method for quantitatively measuring skin impedance. Figure 1 This is a flowchart of a method for quantitatively measuring skin impedance according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0041] S11, acquire the test data of the part to be tested.

[0042] In this embodiment, the skin impedance of three iliac lines and the two middle lines on the forearm was measured. Figure 2 As shown, three meridian lines (Lung Meridian / LU, Pericardium Meridian / PC, and Heart Meridian / HT) and two lines between the meridians (PL / LU and PC; PH / PC and HT) are first identified. It should be noted that this embodiment only uses the above meridian lines as an example for illustration. In actual application, other meridian lines can be selected according to the actual situation. This embodiment is not limited to this.

[0043] S12, based on the data to be measured, the impedance value is determined under different current magnitudes and frequencies. The impedance value is measured using an electrode assembly formed by four silver chloride electrodes. Specifically, after determining each meridian and the intermediate line, as... Figure 3As shown, the electrode assembly was placed on each line, and the impedance was measured under different current magnitudes and frequencies. During the measurement, as... Figure 4 As shown, two external excitation electrodes and two internal measurement electrodes are arranged on a line; each electrode is an Ag / AgCl electrode with a diameter of 4 mm, and conductive adhesive is applied between the electrodes and the skin; the current is provided by a constant current source through the external excitation electrodes; the voltage between the two internal measurement electrodes is measured by a lock-in amplifier; according to Ohm's law, the impedance value is the ratio of voltage to input current.

[0044] S13, Based on the measured impedance value, generate a scatter plot showing the impedance value as a function of current or frequency. Detailed information will be provided in subsequent steps and will not be repeated in this embodiment.

[0045] S14, fit the scatter plot to determine the fitting parameters, and then determine the impedance characteristic parameters corresponding to the data to be measured. After determining the fitting parameters, calculate the impedance value of each line accordingly. Detailed information will be described in subsequent steps, and will not be repeated in this embodiment.

[0046] In another embodiment, a method for quantitatively measuring nonlinear skin impedance is also provided, the process comprising the following steps:

[0047] S21, Obtain the test data of the part to be tested. See step S11 for details, which will not be repeated in this embodiment.

[0048] S22, the impedance value is measured under different current magnitudes and frequencies based on the test data. The impedance value is measured using an electrode assembly formed by four silver chloride electrodes. See step S12 for details; it will not be repeated in this embodiment.

[0049] S23, based on the measured impedance value, generate a scatter plot of the impedance value as a function of current or frequency.

[0050] In this embodiment, a first curve can be generated using impedance value and frequency, and a second curve can be generated using impedance value and current intensity. The first curve is analyzed to determine that the frequency point where the peak value is located is less than 15kHz under different excitation currents. Regression analysis is performed on the second curve to determine that the impedance value changes with the excitation current and to determine the nonlinear characteristics of the impedance.

[0051] Specifically, such as Figure 5 As shown, the impedance value changes in the frequency range of 1-100kHz. It can be seen that there is an impedance peak under different excitation currents. The frequency point where the peak is located is generally less than 15kHz. Above 15kHz, the impedance value decreases as the frequency increases.

[0052] In another embodiment, step S23 above specifically includes, as follows: Figure 6As shown, the impedance values ​​change with current increasing from 0 to 0.67 mA at 20, 50, and 100 kHz. It can be seen that the impedance value increases with increasing excitation current, exhibiting a nonlinear characteristic of impedance variation with current.

[0053] In this embodiment, through fitting analysis of the impedance curve, it is found that when the excitation current is higher than 0.1mA, the change in impedance with current conforms to an exponential function with the reciprocal of the current as the exponent (impedance = a*e). b / current ). Figure 7 As shown, this equation can fit the data very well. The fitting effect is related to the fitting interval. For example, the fitting effect of this interval is better in the 0.1-0.4mA interval than the fitting effect of the 0.07-0.67mA interval.

[0054] The impedance-current curve was found to be an exponential function with the reciprocal of the variable as the exponent (impedance = a * e). b / current After fitting the impedance, the natural logarithm of the impedance (ln(impedance)) and the reciprocal of the current (1 / current) are calculated respectively, so that the parameter values ​​can be obtained through linear regression, thereby determining the characteristics of the nonlinear impedance. Figure 8 The linear fit within the 0.1–0.4 mA range is shown, along with its two important parameters, k and intercept. Based on these parameters, the impedance values ​​under different current conditions can be calculated.

[0055] Impedance value = e intercept *e k / current ,

[0056] Among them, e intercept The estimated maximum impedance value is equivalent to 'a' in the fitting equation, and is the characteristic value of the impedance; 'k' is the linear coefficient, representing the degree to which the impedance value is affected by the current, equivalent to 'b' in the fitting equation; and 'current' represents the current.

[0057] In another specific embodiment, utilizing Figure 2 , Figure 3 and Figure 4 The method and apparatus shown employ Figure 8 The method shown was used to determine, as Figure 2 The image shows the three yin meridians of the arm and their adjacent resistances; Figure 9 The impedance of the pericardium meridian (PC) is lower than that of the bilateral meridians, while the impedance of the lung meridian (LU) and heart meridian (HT) is not higher than that of the bilateral meridians; the skin impedance on the inner side of the arm appears to change continuously, that is, it is lowest in the middle and increases towards the ulnar and radial sides. In practical applications, the method of this embodiment can also be used for the analysis of skin moisture and body composition, but this embodiment is not limited thereto.

[0058] The method for quantitatively measuring skin impedance provided in this invention obtains new evaluation parameters by quantifying the linearity and magnitude of skin impedance. These parameters are used to quantitatively evaluate nonlinear skin impedance characteristics and can be applied to impedance analysis-related scenarios. On the one hand, this improves the technical level of instrument development for clinical monitoring and diagnosis based on bioimpedance technology; on the other hand, it can contribute to the study of the essence of meridians.

[0059] The method for quantitatively measuring skin impedance provided in this invention obtains new evaluation parameters by quantifying the linearity and magnitude of skin impedance. These parameters are used to quantitatively evaluate nonlinear skin impedance characteristics and are applied to impedance analysis-related scenarios. On the one hand, this improves the technical level of instrument development for clinical monitoring and diagnosis based on bioimpedance technology; on the other hand, it can contribute to the research and development of the essence of meridians.

[0060] This embodiment provides a device for quantitatively measuring skin impedance. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0061] This invention discloses a device for quantitatively measuring skin impedance, such as... Figure 10 As shown, it includes:

[0062] The first processing module 01 is used to acquire the test data of the part to be tested;

[0063] The second processing module 02 is used to determine the impedance value under different current magnitudes and frequencies based on the data to be measured. The impedance value is determined by an electrode assembly formed by four silver chloride electrodes.

[0064] The third processing module 03 is used to generate a scatter plot of impedance values ​​as a function of current or frequency based on the measured impedance values.

[0065] The fourth processing module 04 is used to fit the scatter plot, determine the fitting parameters, and then determine the parameters of the impedance characteristics corresponding to the data to be measured.

[0066] The device for quantitatively measuring skin impedance provided in this invention obtains new evaluation parameters by quantifying the linearity and magnitude of skin impedance. These parameters are used to quantitatively evaluate nonlinear skin impedance characteristics and are applied in impedance analysis-related scenarios. On the one hand, this improves the technical level of instrument development for clinical monitoring and diagnosis based on bioimpedance technology; on the other hand, it can contribute to the research and development of the essence of meridians.

[0067] This invention also provides an electronic device, please refer to [link / reference]. Figure 11 , Figure 11This is a schematic diagram of the structure of an electronic device provided in an optional embodiment of the present invention, such as... Figure 11 As shown, the electronic device may include: at least one processor 601, such as a CPU (Central Processing Unit), at least one communication interface 603, memory 604, and at least one communication bus 602. The communication bus 602 is used to enable communication between these components. The communication interface 603 may include a display screen or a keyboard; optionally, the communication interface 603 may also include a standard wired interface or a wireless interface. The memory 604 may be high-speed RAM (Random Access Memory) or non-volatile memory, such as at least one disk storage device. Optionally, the memory 604 may also be at least one storage device located remotely from the aforementioned processor 601. The processor 601 may be combined with... Figure 11 The described apparatus has an application program stored in memory 604, and a processor 601 calls the program code stored in memory 604 to perform any of the above method steps.

[0068] The communication bus 602 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The communication bus 602 can be divided into an address bus, a data bus, and a control bus, etc. For ease of representation, Figure 11 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0069] The memory 604 may include volatile memory, such as random-access memory (RAM); the memory may also include non-volatile memory, such as flash memory, hard disk drive (HDD) or solid-state drive (SSD); the memory 604 may also include a combination of the above types of memory.

[0070] The processor 601 can be a central processing unit (CPU), a network processor (NP), or a combination of CPU and NP.

[0071] The processor 601 may further include a hardware chip. This hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0072] Optionally, the memory 604 is also used to store program instructions. The processor 601 can invoke the program instructions to implement the method for quantitatively measuring skin impedance as shown in the embodiments of this application.

[0073] This invention also provides a non-transitory computer storage medium storing computer-executable instructions that can execute the method for quantitatively measuring skin impedance in any of the above-described method embodiments. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium may also include combinations of the above types of memory.

[0074] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for quantitatively measuring skin impedance, characterized in that, include: Obtain the test data for the part to be tested; The impedance values ​​are determined based on the test data under different current magnitudes and frequencies, and the impedance values ​​are measured through an electrode group formed by four silver chloride electrodes. Based on the measured impedance value, a scatter plot of the impedance value as a function of current or frequency is generated. The scatter plot is fitted to determine the fitting parameters, and then the parameters of the impedance characteristics corresponding to the data to be measured are determined. The step of generating a scatter plot of impedance values ​​as a function of current or frequency based on the measured impedance values ​​includes: A scatter plot is generated using the current and the measured impedance value. The process of fitting the scatter plot and determining the fitting parameters includes: The fitting equation is determined based on the impedance value and the current in the scatter plot, thereby determining the fitting parameters; The fitting equation is expressed as follows: impedance value , Where a is the estimated maximum impedance value; b is the linearity coefficient, which indicates the degree to which the impedance value is affected by the current; and current represents the current.

2. The method according to claim 1, characterized in that, The step of determining the impedance value under different current magnitudes and frequencies based on the test data, wherein the impedance value is determined through an electrode assembly formed by four silver chloride electrodes, includes: The electrode group is configured using four-electrode technology; The impedance values ​​at different currents at a preset frequency are measured using the electrode assembly.

3. The method according to claim 1, characterized in that, The method is applied to body composition analysis via skin impedance measurement, including the evaluation of water content, fat content, and muscle mass.

4. The method according to claim 1, characterized in that, The method has also been applied to the analysis of body meridian impedance and the derived evaluation of meridian function.

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