Bioimpedance measurement method and system based on multi-channel radio frequency transmission

Abstract

A bioimpedance measurement method and system based on multi-channel radio frequency transmission. The bioimpedance measurement method comprises the following steps: setting measurement-related parameters; a channel radio frequency control module switches from a radio frequency mode to a measurement mode; opening a measurement channel unit, adjusting the DCP value of the channel to a set second DCP value, closing the remaining channel units, and adjusting the DCP value of the closed channels to 0; the measurement channel unit emits a radio frequency signal, and analog DC voltage and analog DC current are obtained after conversion via circuits; an analog-to-digital conversion module collects the analog DC voltage and the analog DC current a set number of times and converts same into corresponding digital signals; and according to an impedance fitting formula, performing a calculation to obtain the impedance value of a current measurement by the channel.

Description

A bioimpedance measurement method and system based on multi-channel radio frequency transmission Technical Field

[0001] The present invention relates to a bioimpedance measurement method based on multi-channel radio frequency transmission, and also relates to a corresponding bioimpedance measurement system, belonging to the technical field of diagnostic measurement. Background Art

[0002] Bioimpedance measurement is a testing technology that uses the electrical properties of biological tissues and organs and their patterns of change to extract biomedical information related to human physiological and pathological conditions. This technology typically uses a system of electrodes placed on the body surface to deliver a small AC current or voltage to the subject, detecting the corresponding electrical impedance and its changes. As one of the key parameters reflecting human physiological conditions, bioimpedance is a crucial indicator used by many physiological parameter detection devices. Therefore, the accuracy of bioimpedance measurements is crucial.

[0003] In the prior art, bioimpedance measurement methods primarily include hardware impedance converters and software data fitting methods. The hardware impedance converter method is relatively complex to implement, employing a detection system consisting of a DDS (signal generation) module, a DAC module, a GAIN (amplification) module, an ADC module, an FFT (Fourier transform) module, and a filter module. The DDS module transmits a fixed-frequency signal through the DAC module to the characteristic tissue to be detected. After adjustment by the GAIN module, the ADC module acquires the voltage and current amplitudes. After measuring the amplitudes at multiple points, the FFT module calculates the specific characteristic impedance value. However, when this method is applied to multi-channel RF signal transmission, the complexity of signal differentiation increases exponentially due to the complex models of multiple RF signals in human tissue. Even with a high-frequency impedance converter, distinguishing between DDS and RF signals still requires a modular differentiation circuit. Therefore, it is not suitable for multi-channel RF transmission methods. The software data fitting method utilizes a large amount of collected voltage, current, and real-world impedance data to find the linear relationship between voltage, current, and impedance. This linear relationship, along with the real-time collected voltage and current values, is then used to derive the true impedance value during RF signal transmission. This method requires a relatively simple structure, including a voltage conversion module, a current conversion module, and an ADC module. However, as the RF signal power increases and becomes no longer a standard sine wave, the measurement error increases, significantly affecting the accurate measurement of bioimpedance. Summary of the Invention

[0004] The primary technical problem to be solved by the present invention is to provide a bioimpedance measurement method based on multi-channel radio frequency transmission.

[0005] Another technical problem to be solved by the present invention is to provide a bioimpedance measurement system based on multi-channel radio frequency transmission.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] According to a first aspect of an embodiment of the present invention, a bioimpedance measurement method based on multi-channel radio frequency transmission is provided, comprising the following steps:

[0008] (1) Setting measurement-related parameters, including at least the number of channel units used in this operation, the number of voltage and current acquisition times, and the second DCP value of the channel;

[0009] (2) Determine whether an impedance measurement command has been received; if so, proceed to the next step;

[0010] (3) The channel RF control module switches from RF mode to measurement mode and records the first DCP value of each channel;

[0011] (4) turning on the measurement channel unit and adjusting the DCP value of the channel to the set second DCP value; at the same time, turning off the remaining channel units and adjusting the DCP values ​​of the turned-off channels to 0;

[0012] (5) The measurement channel unit emits a radio frequency signal, which is converted by the circuit to obtain an analog DC voltage and an analog DC current; the analog-to-digital conversion module collects the analog DC voltage and the analog DC current a set number of times, converts them into corresponding digital signals, and sends them to the microcontroller module;

[0013] (6) The microcontroller module calculates according to the impedance fitting formula to obtain the impedance value of the channel measured this time, and stores it in the buffer area of ​​the corresponding channel inside the microcontroller module; at the same time, the counter value is increased by 1;

[0014] (7) Determine whether the count value of the counter is equal to the set number of channel units; when the count value is less than the set number of channel units, proceed to step (4) to measure the next channel unit; when the count value is equal to the set number of channel units, proceed to the next step;

[0015] (8) Calculating the current impedance average value of each channel based on the multiple impedance values ​​of each channel measured, and projecting the impedance average value on the display; at the same time, the counter is reset;

[0016] (9) After the impedance measurement is completed, the channel RF control module switches from the measurement mode to the RF mode, and restores the DCP value of each channel to the first DCP value;

[0017] (10) Determine whether to end the impedance measurement during this operation; if the measurement is ended, proceed to the next step; if the next measurement is to be performed, proceed to step (2);

[0018] (11) End the impedance measurement.

[0019] Preferably, in step (6), the impedance value val(x,y) measured this time is calculated by the following formula: val(x,y)=p00+(p10*x)+(p01*y)+(p20*x 2 )+(p11*x*y)+(p30 *x 3 )+(p21*x 2 *y)

[0020] Wherein, x is the direct impedance value of this measurement; y is the first DCP value; p00, p10, p01, p20, p11, p30, and p21 are all p coefficients.

[0021] Preferably, the direct impedance value x is calculated by the following formula: x=Vz_avg / Iz_avg

[0022] Among them, Vz_avg is the average voltage, and Iz_avg is the average current.

[0023] Preferably, when the second DCP value is set to 20, the values ​​of the p coefficient are as follows: p00 = -102.7; p10 = 448.6; p01 = 0.01481; p20 = -301.4; p11 = -0.03425; p30 = 117.7; and p21 = 0.02582.

[0024] Preferably, in step (6), the cache area of ​​each channel inside the microcontroller module is set to a uniform number of times to store the impedance value. When the number of times the impedance value is stored exceeds the set number, the cache area of ​​each channel updates the stored impedance value according to the first-in-first-out principle.

[0025] According to a second aspect of an embodiment of the present invention, a bioimpedance measurement system based on multi-channel radio frequency transmission is provided, comprising a microcontroller module, a host computer and at least one channel unit; wherein,

[0026] The host computer is connected to the microcontroller module and is used to monitor and control the measurement process of bioimpedance;

[0027] The microcontroller module is connected to each of the channel units respectively, and is used to control the working state of each of the channel units, and perform calculations based on the measurement results of the channel units to finally obtain an impedance average value;

[0028] The channel unit is used to generate and output radio frequency energy and measure the impedance of biological tissue.

[0029] Preferably, each of the channel units includes a channel radio frequency control module, a transformer, a current transformer, a voltage transformer, a first rectifier circuit, a second rectifier circuit, a first relay and an analog-to-digital conversion module; wherein,

[0030] The output end of the channel RF control module is connected to the input end of the transformer, the output end of the transformer is connected to the input end of the first relay through the current transformer and the voltage transformer, and the output end of the first relay is connected to the electrode close to the biological tissue; the output ends of the current transformer and the voltage transformer are respectively connected to the input end of the analog-to-digital conversion module through the first rectifier circuit and the second rectifier circuit, the output end of the analog-to-digital conversion module is connected to the input end of the microcontroller module, the first output end of the microcontroller module is connected to the control end of the channel RF control module, and at the same time, the second output end of the microcontroller module is connected to the control end of the first relay.

[0031] Preferably, the channel radio frequency control module includes a signal generator, a signal amplifier, a digital potentiometer, a drive amplifier and a second relay; wherein,

[0032] The output end of the signal generator is connected to the input end of the signal amplifier, the output end of the signal amplifier is connected to the input end of the digital potentiometer, the output end of the digital potentiometer is connected to the input end of the driving amplifier, and the output end of the driving amplifier is connected to the transformer in the channel unit;

[0033] The first control signal end of the microcontroller module is connected to the control end of the digital potentiometer, and the second control signal end of the microcontroller module is connected to the control end of the second relay; the input end of the second relay is connected to the power supply end, and the output end of the second relay is connected to the power supply end of the driving amplifier.

[0034] Compared to existing technologies, the bioimpedance measurement method based on multi-channel RF transmission provided by the present invention utilizes a microcontroller module to precisely control each channel unit, enabling multiple acquisitions of each channel under the same stable RF signal. Furthermore, the control, acquisition, and feedback of each channel are independently configured to avoid mutual interference between channels and achieve accurate bioimpedance measurement. Furthermore, because the bioimpedance measurement system utilizes relatively simple and technologically mature functional modules such as a transformer, mutual inductor, analog-to-digital conversion module, and microcontroller module, the bioimpedance measurement system exhibits excellent stability, low cost, and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a circuit diagram of a bioimpedance measurement system based on multi-channel radio frequency transmission in an embodiment of the present invention;

[0036] FIG2 is a schematic structural diagram of a channel radio frequency control module according to an embodiment of the present invention;

[0037] FIG3 is a flow chart of a bioimpedance measurement method based on multi-channel radio frequency transmission in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The technical content of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] As shown in Figure 1, the bioimpedance measurement system based on multi-channel radio frequency transmission provided by an embodiment of the present invention includes at least a microcontroller module (MCU), a host computer, and at least one channel unit. Each channel unit includes a channel radio frequency control module, a transformer, a current transformer, a voltage transformer, a first rectifier circuit, a second rectifier circuit, a first relay, and an analog-to-digital conversion module (ADC).

[0040] The microcontroller module controls the operating status of each channel unit and performs calculations based on the channel unit's measurement results, ultimately deriving the average impedance value. A host computer communicates with the microcontroller module to monitor and control the bioimpedance measurement process. Each channel unit is responsible for generating and outputting RF energy and measuring the impedance of biological tissue. Each channel unit has a similar structure; the following uses the first channel unit as an example for structural description.

[0041] The channel RF control module is used to generate RF signals, control the output RF signal level, and open and close the channel. Its structure, shown in Figure 2, includes a signal generator, a signal amplifier, a digital potentiometer, a driver amplifier, and a second relay. The signal generator (DDS) generates a sinusoidal RF signal of a specific frequency and amplitude; the signal amplifier amplifies the RF signal; the digital potentiometer adjusts the output RF signal amplitude based on the MCU control signal; the driver amplifier drives and amplifies the RF signal; and the second relay controls the on / off state of the driver amplifier's operating power supply based on the MCU control signal.

[0042] In the channel RF control module, the output RF signal of the channel is dynamically adjusted by a digitally controlled potentiometer (DCP) controlled by the MCU via the I2C bus. The specific adjustment value of the digital potentiometer is recorded as the DCP value. The channel RF control module operates in two modes: RF mode and measurement mode. RF mode is primarily used to provide energy for intraoperative procedures (such as ablation) to generate a thermal effect in human tissue. The DCP value of the channel in RF mode is recorded as the first DCP value. The measurement mode is primarily used for measuring the impedance of biological tissue. The DCP value of the channel in measurement mode is recorded as the second DCP value.

[0043] In one embodiment of the present invention, the digital potentiometer is a X9C103 high-precision digital potentiometer, and the output potential adjustment has 100 gears (also called 100 steps or taps), that is, the adjustment range of the DCP value is 0 to 100.

[0044] The transformer is used to step down the AC voltage output by the channel RF control module so that the output voltage on the secondary side of the transformer meets the measurement requirements.

[0045] The voltage transformer and current transformer are used to convert the voltage and current output from the secondary side of the transformer so that the secondary voltage output by the voltage transformer and the secondary current output by the current transformer meet the measurement requirements of the analog-to-digital conversion module.

[0046] The first rectifier circuit and the second rectifier circuit are used to convert the secondary voltage output by the voltage transformer and the secondary current output by the current transformer into a DC voltage and a DC current, respectively.

[0047] The analog-to-digital conversion module is used to measure the DC voltage and DC current of the current circuit and convert them into digital signals and output them to the microcontroller module.

[0048] The first relay is used to control the on / off state of the channel unit according to the control signal of the MCU.

[0049] As shown in FIG3 , an embodiment of the present invention provides a bioimpedance measurement method based on multi-channel radio frequency transmission, comprising the following steps:

[0050] S1: Set measurement-related parameters. The parameters that need to be set include at least the number of channel units N used in this operation, the number of voltage and current acquisition times M, and the second DCP value of the channel. Where N and M are both positive integers.

[0051] Typically, the second DCP value of a channel is a fixed value. In one embodiment of the present invention, the second DCP value of each channel is 20.

[0052] S2: Determine whether an impedance measurement command is received; if a measurement command is received, proceed to the next step.

[0053] S3: The channel radio frequency control module switches from radio frequency mode to measurement mode, and at the same time, records the first DCP value of each channel.

[0054] When the working mode of the channel RF control module is switched, the DCP value of each channel in the RF mode (i.e., the first DCP value) needs to be recorded and saved. After the measurement is completed, when the working mode of the channel RF control module is switched back to the RF mode, each channel needs to be restored to the original first DCP value.

[0055] S4: Turn on the measurement channel unit and adjust the DCP value of the channel to the set second DCP value; at the same time, turn off the remaining channel units and adjust the DCP values ​​of the turned-off channels to 0.

[0056] It should be noted that, for the number N of channel units used in this operation, the first channel unit is opened and the 2-N channel units are closed for the first time; the second channel unit is opened and the 1, 3-N channel units are closed for the second time, until all channel units are measured in a cycle.

[0057] S5: The measurement channel unit sends out an RF signal, which is converted by the circuit to obtain an analog DC voltage Vz and an analog DC current Iz; the ADC module collects the analog DC voltage Vz and the analog DC current Iz M times, converts them into corresponding digital signals, and sends them to the microcontroller module.

[0058] S6: The microcontroller module calculates according to the impedance fitting formula to obtain the impedance value val(x,y) of the channel measured this time, and stores it in the buffer area of ​​the corresponding channel inside the MCU; at the same time, the counter value is increased by 1.

[0059] The buffer area of ​​each channel is uniformly set to save a number of impedance values, for example, it is set to save 10 impedance values. When the number of stored impedance values ​​exceeds the set number, the buffer area of ​​each channel updates the stored impedance value according to the first-in-first-out principle.

[0060] The impedance calculation process of this measurement channel is as follows:

[0061] First, calculate the average values ​​of voltage and current respectively. Based on the M sampling results, the voltage average value Vz_avg and the current average value Iz_avg are: Vz_avg=(Vz1+Vz2+Vz3+…+Vzm) / M (1) Iz_avg=(Iz1+Iz2+Iz3+…+Izm) / M (2)

[0062] Among them, Vz1, Vz2, Vz3, ..., Vzm are DC voltage values ​​obtained by sampling M times respectively; Iz1, Iz2, Iz3, ..., Izm are DC current values ​​obtained by sampling M times respectively.

[0063] Second, calculate the direct impedance value x: x=Vz_avg / Iz_avg (3)

[0064] Third, calculate the impedance value val(x,y) of this measurement according to the impedance fitting formula: val(x,y)=p00+(p10*x)+(p01*y)+(p20*x 2 )+(p11*x*y)+(p30* x 3 )+(p21*x 2 *y) (4)

[0065] Where x is the direct impedance value measured; y is the first DCP value; p00, p10, p01, p20, p11, p30, and p21 are all p-coefficients, obtained by polynomial fitting of a large amount of test data. When the second DCP value is 20, the values ​​and ranges of these p-coefficients are shown in Table 1.

[0066] Table 1

[0067] The impedance fitting formula shown in formula (4) is obtained by switching from the RF mode to the measurement mode multiple times and collecting a large number of current, voltage and first DCP values ​​under different second DCP values.

[0068] S7: Determine whether the count value of the counter is equal to the number of channel units N; when the count value is less than N, go to step S4 to measure the next channel unit; when the count value is equal to N, go to the next step.

[0069] S8: Based on the multiple impedance values ​​of each channel measured, the current impedance average value of each channel is calculated and displayed on the display. At the same time, the counter is reset.

[0070] It should be noted that the multiple impedance values ​​of each channel refer to multiple measurement values ​​stored in the corresponding channel buffer area inside the MCU.

[0071] S9: After the impedance measurement is completed, the channel RF control module switches from the measurement mode to the RF mode, and restores the DCP value of each channel to the first DCP value.

[0072] S10: Determine whether to end the impedance measurement during this operation; if the measurement is ended, proceed to the next step; if the next measurement is to be performed, proceed to step S2.

[0073] S11: End the impedance measurement.

[0074] The above describes in detail the bioimpedance measurement method based on multi-channel RF transmission provided by the present invention. On this basis, an embodiment of the present invention further provides a bioimpedance measurement system based on multi-channel RF transmission for implementing the above-mentioned bioimpedance measurement method. Referring to Figure 1 , the bioimpedance measurement system includes a microcontroller module, a host computer, and at least one channel unit. Each channel unit includes a channel RF control module, a transformer, a current transformer, a voltage transformer, a first rectifier circuit, a second rectifier circuit, a first relay, and an analog-to-digital conversion module.

[0075] The host computer is connected to the microcontroller module, which is in turn connected to each channel unit. In each channel unit, the output of the channel radio frequency control module is connected to the input of a transformer, which is connected to the input of a first relay via a current transformer and a voltage transformer, and the output of the first relay is connected to an electrode in close contact with biological tissue. The outputs of the current transformer and the voltage transformer are connected to the input of an analog-to-digital conversion module via a first rectifier circuit and a second rectifier circuit, respectively. The output of the analog-to-digital conversion module is connected to the input of the microcontroller module, the first output of the microcontroller module is connected to the control terminal of the channel radio frequency control module, and the second output of the microcontroller module is connected to the control terminal of the first relay.

[0076] The microcontroller module controls the operating status of each channel unit and performs calculations based on the channel unit's measurement results, ultimately deriving the average impedance value. The host computer communicates with the microcontroller module to monitor and control the bioimpedance measurement process. The channel units generate and output RF energy and measure the impedance of biological tissue.

[0077] The channel RF control module in the channel unit includes a signal generator, a signal amplifier, a digital potentiometer, a drive amplifier, and a second relay. The output of the signal generator is connected to the input of the signal amplifier, which is connected to the input of the digital potentiometer, which is connected to the input of the drive amplifier, which is connected to the transformer in the channel unit. The first control signal terminal of the MCU is connected to the control terminal of the digital potentiometer, and the second control signal terminal of the MCU is connected to the control terminal of the second relay. The input of the second relay is connected to the power supply terminal, and the output of the second relay is connected to the power supply terminal of the drive amplifier.

[0078] The signal generator is used to generate a sinusoidal RF signal of a certain frequency and amplitude; the signal amplifier is used to amplify the RF signal; the digital potentiometer is used to adjust the amplitude of the output RF signal according to the MCU control signal; the drive amplifier is used to drive and amplify the RF signal; the second relay is used to control the on / off state of the working power supply of the drive amplifier according to the MCU control signal.

[0079] In summary, compared with the prior art, the bioimpedance measurement method based on multi-channel RF transmission provided by the present invention utilizes a microcontroller module to precisely control each channel unit, enabling multiple acquisitions of each channel under the same stable RF signal. Furthermore, the control, acquisition, and feedback of each channel are independently configured to avoid mutual interference between channels and achieve accurate bioimpedance measurement. Furthermore, because the bioimpedance measurement system utilizes relatively simple and technologically mature functional modules such as a transformer, mutual inductor, analog-to-digital conversion module, and microcontroller module, the bioimpedance measurement system exhibits excellent stability, low cost, and high reliability.

[0080] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0081] The above describes in detail the bioimpedance measurement method and system based on multi-channel radio frequency transmission provided by the present invention. For those skilled in the art, any obvious modification made thereto without departing from the essence of the present invention would constitute an infringement of the present invention's patent rights and would result in the corresponding legal liability.

Claims

1. A bio-impedance measurement method based on multi-channel radio frequency transmission, characterized in that It includes the following steps: (1) Set the parameters related to measurement, including at least the number of channel units used during this operation, the number of voltage and current acquisitions, and the second DCP value of the channels; (2) Determine whether an impedance measurement command is received; if the measurement command is received, proceed to the next step; (3) The channel radio frequency control module switches from the radio frequency mode to the measurement mode, and at the same time, records the first DCP value of each channel; (4) Turn on the measurement channel unit, and adjust the DCP value of this channel to the set second DCP value; at the same time, turn off the remaining channel units, and adjust the DCP value of the turned-off channels to 0; (5) The measurement channel unit emits a radio frequency signal, and after circuit conversion, an analog DC voltage and an analog DC current are obtained; the analog-to-digital conversion module acquires the analog DC voltage and the analog DC current a set number of times, and converts them into corresponding digital signals and sends them to the microcontroller module; (6) The microcontroller module calculates according to the impedance fitting formula to obtain the impedance value measured for this channel this time, and stores it in the buffer area of the corresponding channel inside the microcontroller module; at the same time, the counter value is incremented by 1; (7) Determine whether the count value of the counter is equal to the set number of channel units; when the count value is less than the set number of channel units, go to step (4) to perform the measurement of the next channel unit; when the count value is equal to the set number of channel units, proceed to the next step; (8) According to the multiple impedance values of each channel measured, calculate the current impedance average value of each channel, and project and display the impedance average value through a display; at the same time, the counter is cleared; (9) This impedance measurement ends, the channel radio frequency control module switches from the measurement mode to the radio frequency mode, and restores the DCP value of each channel to the first DCP value; (10) Determine whether to end the impedance measurement during this operation; if the measurement is ended, proceed to the next step; If a next measurement is to be performed, go to step (2); (11) End the impedance measurement.

2. The method for measuring bioimpedance based on multi-channel radio frequency transmission according to claim 1, characterized in that In step (6), the impedance value val(x, y) measured this time is calculated by the following formula: val(x, y) = p00 + (p10 * x) + (p01 * y) + (p20 * x 2 ) + (p11 * x * y) + (p30 * x 3 ) + (p21 * x 2 * y) Wherein, x is the direct impedance value measured this time; y is the first DCP value; p00, p10, p01, p20, p11, p30, p21 are all p coefficients.

3. The bioimpedance measurement method based on multi-channel radio frequency transmission according to claim 2, wherein The direct impedance value x is calculated by the following formula: x = Vz_avg / Iz_avg Wherein, Vz_avg is the average voltage, and Iz_avg is the average current.

4. The method for measuring bio-impedance based on multi-channel radio frequency transmission according to claim 2, characterized in that When the second DCP value is set to 20, the values of the p coefficients are as follows: p00 = -102.7; p10 = 448.6; p01 = 0.01481; p20 = -301.4; p11 = -0.03425; p30 = 117.7; p21 = 0.02582.

5. The bio-impedance measurement method based on multi-channel radio frequency transmission according to claim 1, characterized in that In step (6): The buffer areas of each channel inside the microcontroller module are set with a unified number of times for storing the impedance values; when the number of times of storing the impedance values exceeds the set number of times, the buffer areas of each channel update the stored impedance values according to the principle of first in first out.

6. A bioimpedance measurement system based on multi-channel radio frequency transmission, characterized in that It includes a microcontroller module, a host computer, and at least one channel unit; wherein, The host computer is connected to the microcontroller module and is used to supervise and control the measurement process of bio-impedance; The microcontroller module is respectively connected to each of the channel units, and is used to control the working states of the channel units and calculate according to the measurement results of the channel units, and finally obtain the impedance average value; The channel unit is used to generate and output radio frequency energy and measure the impedance of biological tissue.

7. The bio-impedance measurement system based on multi-channel radio frequency transmission according to claim 6, characterized in that: Each of the channel units includes a channel radio frequency control module, a transformer, a current transformer, a voltage transformer, a first rectification circuit, a second rectification circuit, a first relay and an analog-to-digital conversion module; wherein, The output end of the channel radio frequency control module is connected to the input end of the transformer, the output end of the transformer is connected to the input end of the first relay through the current transformer and the voltage transformer, and the output end of the first relay is connected to the electrode in contact with the biological tissue; the output ends of the current transformer and the voltage transformer are respectively connected to the input end of the analog-to-digital conversion module through the first rectification circuit and the second rectification circuit, the output end of the analog-to-digital conversion module is connected to the input end of the microcontroller module, and the first output end of the microcontroller module is connected to the control end of the channel radio frequency control module. At the same time, the second output end of the microcontroller module is connected to the control end of the first relay.

8. The bio-impedance measurement system based on multi-channel radio frequency transmission according to claim 7, characterized in that: The channel radio frequency control module includes a signal generator, a signal amplifier, a digital potentiometer, a drive amplifier and a second relay; wherein, The output end of the signal generator is connected to the input end of the signal amplifier, the output end of the signal amplifier is connected to the input end of the digital potentiometer, the output end of the digital potentiometer is connected to the input end of the drive amplifier, and the output end of the drive amplifier is connected to the transformer in the channel unit; The first control signal end of the microcontroller module is connected to the control end of the digital potentiometer, and the second control signal end of the microcontroller module is connected to the control end of the second relay; the input end of the second relay is connected to the power supply terminal, and the output end of the second relay is connected to the power supply end of the drive amplifier.

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