CN118105052A - Biological impedance measurement method and system based on multichannel radio frequency emission - Google Patents
Biological impedance measurement method and system based on multichannel radio frequency emission Download PDFInfo
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Abstract
The invention discloses a bio-impedance measurement method and system based on multichannel radio frequency emission. The bio-impedance measurement method comprises the following steps: setting measurement related parameters; the channel radio frequency control module is switched from a radio frequency mode to a measurement mode; opening a measuring channel unit, adjusting the DCP value of the channel to be a set second DCP value, closing the rest channel units, and adjusting the DCP value of the closed channel to be 0; the measuring channel unit sends out radio frequency signals, and analog direct current voltage and analog direct current are obtained after the radio frequency signals are converted by the circuit; the analog-to-digital conversion module collects the analog direct-current voltage and the analog direct-current for a set number of times and converts the analog direct-current voltage and the analog direct-current into corresponding digital signals; and calculating according to an impedance fitting formula to obtain the impedance value of the current measurement of the channel.
Description
Technical Field
The invention relates to a bioelectrical impedance measuring method based on multichannel radio frequency emission, and also relates to a corresponding bioelectrical impedance measuring system, belonging to the technical field of diagnosis and measurement.
Background
The bioimpedance measurement is a detection technology for extracting biomedical information related to physiological and pathological conditions of human body by utilizing the electrical characteristics of biological tissues and organs and the change rule thereof, and is usually used for detecting corresponding electrical impedance and the change condition thereof by sending tiny alternating current measurement current or voltage to a detection object by means of an electrode system arranged on the body surface. Bioimpedance, one of the important parameters reflecting the physiological condition of the human body, is an important index that many physiological parameter detection devices need to detect. Therefore, the accuracy of the bioimpedance measurement is important.
In the prior art, the measuring method of the biological impedance mainly comprises a hardware impedance converter method and a software data fitting method. The hardware impedance converter method is complex to realize, a DDS (signal generation) module, a DAC module, a GAIN (amplification) module, an ADC module, an FFT (fast Fourier computing) module, a filtering module and the like are adopted to form a detection system, a signal with fixed frequency emitted by the DDS module is utilized to reach a characteristic tissue to be detected through the DAC module, the ADC module collects voltage and current amplitude values after being regulated by the GAIN module, and a specific characteristic impedance value is calculated through the FFT module after measuring the multipoint amplitude values. However, when the method is applied to multichannel radio frequency signal transmission, the complexity of signal discrimination is increased in multiple because of the complex model of the multichannel radio frequency signals in human tissues, and a module discrimination circuit is still needed for discriminating the DDS signals and the radio frequency signals even though a high-frequency impedance converter is adopted. Therefore, it is not suitable for the multi-channel radio frequency transmission method. The software data fitting method is to find out the linear relation between the voltage, the current and the impedance after using a large amount of collected voltage, current and real impedance data, and deduce the real impedance value by using the linear relation and the voltage value and the current value collected in real time in the process of transmitting the radio frequency signal. The method is realized by adopting a relatively simple structure such as a voltage conversion module, a current conversion module, an ADC module and the like, but with the increase of the power of the radio frequency signal, when the radio frequency signal is no longer a standard sine wave, the measurement error is larger. Thus, accurate measurement of bioimpedance is greatly affected.
In China patent application No. 202011003530.3, a system and method for testing bioelectric impedance of a multichannel microelectrode is disclosed. The test system comprises an MCU control circuit, a multi-stage power supply circuit, a sine wave generation circuit, an attenuator circuit, a measurement circuit, an amplifier circuit, a multi-channel ADC conversion circuit, an upper computer communication circuit and a data selector circuit. The MCU control circuit performs data arrangement and calculation by applying fine micro-current to the impedance end to be measured and amplifying signals through the multistage precision operational amplifier so as to realize impedance measurement. The impedance testing method is realized by nanoampere-level low current and low voltage, and is not suitable for biological impedance measurement under the radio frequency condition.
Disclosure of Invention
The primary technical problem to be solved by the invention is to provide a bioelectrical impedance measurement method based on multichannel radio frequency emission.
Another technical problem to be solved by the present invention is to provide a bio-impedance measurement system based on multi-channel radio frequency emission.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
According to a first aspect of an embodiment of the present invention, there is provided a bio-impedance measurement method based on multi-channel radio frequency emission, including the steps of:
(1) Setting measurement related parameters, including at least the number of channel units used in the operation, the number of voltage and current acquisition times and a second DCP value of the channel;
(2) Judging whether an impedance measurement command is received or not; if a measurement command is received, the next step is carried out;
(3) The channel radio frequency control module is switched from a radio frequency mode to a measurement mode, and simultaneously, a first DCP value of each channel is recorded;
(4) Opening a measuring channel unit, and adjusting the DCP value of the channel to the set second DCP value; simultaneously, closing the rest channel units, and adjusting the DCP value of the closed channel to 0;
(5) The measuring channel unit sends out a radio frequency signal, and analog direct current voltage and analog direct current are obtained after the radio frequency signal is converted by a circuit; the analog-to-digital conversion module collects the analog direct-current voltage and the analog direct-current for a set number of times, converts the analog direct-current voltage and the analog direct-current into corresponding digital signals and sends the corresponding digital signals to the microcontroller module;
(6) The microcontroller module calculates according to an impedance fitting formula to obtain the impedance value measured by the channel at this time and stores the impedance value in a buffer area of a corresponding channel in the microcontroller module; meanwhile, the counter value is increased by 1;
(7) Judging whether the count value of the counter is equal to the set number of the channel units; when the count value is smaller than the set number of the channel units, the step (4) is carried out to measure the next channel unit; when the count value is equal to the set number of the channel units, the next step is carried out;
(8) Calculating the current impedance average value of each channel according to the measured multiple impedance values of each channel, and displaying the impedance average value through a display; meanwhile, the counter is cleared;
(9) The impedance measurement is finished, the channel radio frequency control module is switched from a measurement mode to a radio frequency mode, and the DCP value of each channel is restored to the first DCP value;
(10) Judging whether the impedance measurement in the operation is finished or not; if the measurement is finished, the next step is carried out; if the next measurement is carried out, the step (2) is carried out;
(11) The impedance measurement is ended.
Preferably, in step (6), the impedance value val (x, y) measured at this time is calculated by the following formula:
val(x,y)＝p00+(p10*x)+(p01*y)+(p20*x2)+(p11*x*y)+(p30*x3)+(p21*x2*y)
Wherein x is the direct impedance value of the current measurement; y is a first DCP value; p00, p10, p01, p20, p11, p30, p21 are p coefficients.
Wherein preferably the direct impedance value x is calculated by:
x＝Vz_avg/Iz_avg
Where vz_avg is the voltage average and iz_avg is the current average.
Preferably, when the second DCP value is set to 20, the p coefficient takes the following value:
p00＝－102.7；p10＝448.6；p01＝0.01481；p20＝－301.4；p11＝－0.03425；p30＝117.7；p21＝0.02582。
preferably, in step (6), the number of times of storing the impedance value is set uniformly in the buffer area of each channel in the microcontroller module, and when the number of times of storing the impedance value exceeds the set number of times, the buffer area of each channel updates the stored impedance value according to the first-in-first-out principle.
According to a second aspect of an embodiment of the present invention, there is provided a bio-impedance measurement system based on multi-channel radio frequency emission, including a microcontroller module, an upper computer, and at least one channel unit; wherein,
The upper computer is connected with the microcontroller module and is used for supervising and controlling the measuring process of the biological impedance;
the microcontroller module is respectively connected with the channel units and used for controlling the working state of the channel units and calculating according to the measurement results of the channel units to finally obtain an impedance average value;
the channel unit is used for generating and outputting radio frequency energy and measuring impedance of biological tissues.
Preferably, each channel unit comprises a channel radio frequency control module, a transformer, a current transformer, a voltage transformer, a first rectifying circuit, a second rectifying circuit, a first relay and an analog-to-digital conversion module; wherein,
The output end of the channel radio frequency control module is connected with the input end of the transformer, the output end of the transformer is connected with 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 with an electrode which is closely attached to biological tissues; the output ends of the current transformer and the voltage transformer are respectively connected with the input end of the analog-to-digital conversion module through the first rectifying circuit and the second rectifying circuit, the output end of the analog-to-digital conversion module is connected with the input end of the microcontroller module, the first output end of the microcontroller module is connected with the control end of the channel radio frequency control module, and meanwhile, the second output end of the microcontroller module is connected with the control end of the first relay.
Preferably, the channel radio frequency control module comprises a signal generator, a signal amplifier, a digital potentiometer, a driving amplifier and a second relay; wherein,
The output end of the signal generator is connected with the input end of the signal amplifier, the output end of the signal amplifier is connected with the input end of the digital potentiometer, the output end of the digital potentiometer is connected with the input end of the driving amplifier, and the output end of the driving amplifier is connected with the transformer in the channel unit;
The first control signal end of the microcontroller module is connected with the control end of the digital potentiometer, and the second control signal end of the microcontroller module is connected with the control end of the second relay; the input end of the second relay is connected with the power supply end, and the output end of the second relay is connected with the power supply end of the driving amplifier.
Compared with the prior art, the biological impedance measurement method based on multi-channel radio frequency emission, provided by the invention, has the advantages that the micro controller module is adopted to accurately control each channel unit, so that the measurement of each channel is acquired for multiple times under the same stable radio frequency signal, the control, the acquisition and the feedback of each channel are mutually independent, the mutual interference among the channels is avoided, and the accurate measurement of the biological impedance is realized. Meanwhile, the measuring system adopts the transformer, the analog-to-digital conversion module, the microcontroller module and other simpler and technically mature functional modules, so that the measuring system has the beneficial effects of good stability, low implementation cost, high reliability and the like.
Drawings
FIG. 1 is a schematic circuit diagram of a bio-impedance measurement system based on multi-channel RF transmission in accordance with an embodiment of the present invention;
Fig. 2 is a schematic structural diagram of a channel radio frequency control module according to an embodiment of the present invention;
fig. 3 is a flowchart of a bio-impedance measurement method based on multi-channel radio frequency emission according to an embodiment of the present invention.
Detailed Description
The technical contents of the present invention will be described in detail with reference to the accompanying drawings and specific examples.
As shown in fig. 1, the bio-impedance measurement system based on multi-channel radio-frequency emission provided by the embodiment of the invention at least comprises a microcontroller module (abbreviated as MCU), an upper computer and at least one channel unit. Each channel unit comprises a channel radio frequency control module, a transformer, a current transformer, a voltage transformer, a first rectifying circuit, a second rectifying circuit, a first relay and an analog-to-digital conversion module (abbreviated as ADC).
The microcontroller module is used for controlling the working state of each channel unit, calculating according to the measurement result of the channel unit and finally obtaining the impedance average value. The upper computer is communicated with the microcontroller module and is used for supervising and controlling the measuring process of the biological impedance. The channel unit is used for generating and outputting radio frequency energy and measuring the impedance of biological tissues; the structure of each channel unit is the same, and the first channel unit is taken as an example for the explanation of the structure.
The channel radio frequency control module is used for generating radio frequency signals and controlling the magnitude of the output radio frequency signals and opening and closing the channels. The structure is shown in fig. 2, and comprises a signal generator, a signal amplifier, a digital potentiometer, a driving amplifier and a second relay. Wherein, the signal generator (abbreviated as DDS) is used for generating sine wave radio frequency signals with certain frequency and amplitude; the signal amplifier is used for amplifying the radio frequency signal; the digital potentiometer is used for adjusting the amplitude of the output radio frequency signal according to the MCU control signal; the driving amplifier is used for driving and amplifying the radio frequency signals; the second relay is used for controlling the on-off state of the working power supply of the driving amplifier according to the MCU control signal.
In the channel radio frequency control module, the size of the channel output radio frequency signal is dynamically regulated by a digital potentiometer (DIGITALLY CONTROLLED POTENTIOMETERS, abbreviated as DCP) controlled by the MCU through an I2C bus, and the specific regulation value of the digital potentiometer is recorded as the DCP value. The working model of the channel radio frequency control module is divided into a radio frequency mode and a measuring mode, wherein the radio frequency mode is mainly used for providing energy in operation (such as ablation) to enable human tissues to generate a thermal effect, and the DCP value of the channel in the radio frequency mode is recorded as a first DCP value; the measurement mode is mainly used for impedance measurement of biological tissues, and the DCP value of the channel in the measurement mode is recorded as a second DCP value.
In one embodiment of the invention, the digital potentiometer is an X9C103 type high precision digital potentiometer, the output potential of which is regulated to have 100 gears (also called 100 steps or taps), namely, the regulating range of DCP value is 0-100.
The transformer is used for carrying out step-down treatment on the alternating voltage output by the channel radio frequency control module, so that the output voltage of the secondary side of the transformer meets the measurement requirement.
The voltage transformer and the current transformer are used for converting the voltage and the current output by 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 requirement of the analog-to-digital conversion module.
The first rectifying circuit and the second rectifying circuit are respectively used for converting the secondary voltage output by the voltage transformer and the secondary current output by the current transformer into direct-current voltage and direct-current.
The analog-to-digital conversion module is used for measuring the direct-current voltage and the direct-current of the current circuit and converting the direct-current voltage and the direct-current into digital signals to be output to the microcontroller module.
The first relay is used for controlling the on-off state of the channel unit according to the control signal of the MCU.
As shown in fig. 3, the bio-impedance measurement method based on multi-channel radio-frequency emission provided by the embodiment of the invention includes the following steps:
S1: setting measurement related parameters; the parameters to be set at least comprise the number N of channel units used in the operation, the number M of voltage and current acquisition times and the second DCP value of the channel. Wherein N and M are positive integers.
Typically, the second DCP value of the channel is a fixed value. In one embodiment of the invention, the second DCP value for each channel is 20.
S2: judging whether an impedance measurement command is received or not; if a measurement command is received, the process proceeds to the next step.
S3: the channel radio frequency control module is switched from a radio frequency mode to a measurement mode, and simultaneously, a first DCP value of each channel is recorded.
When the working mode of the channel radio frequency control module is switched, the DCP value (namely the first DCP value) of each channel in the radio frequency mode is required to be recorded and stored, and when the working mode of the channel radio frequency control module is switched to the radio frequency mode again after the measurement is finished, each channel is required to be restored to the original first DCP value.
S4: opening a measuring channel unit, and adjusting the DCP value of the channel to a set second DCP value; at the same time, the remaining channel units are closed, and the DCP value of the closed channel is adjusted to 0.
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 unit is closed for the first time; and opening the second channel unit and closing the 1, 3-N channel units for the second time until all the channel units are circularly measured.
S5: the measurement channel unit sends out a radio frequency signal, and analog direct current voltage Vz and analog direct current Iz are obtained after the radio frequency signal is converted by a circuit; the ADC module collects the analog direct current voltage Vz and the analog direct current Iz for M times, converts the analog direct current voltage Vz and the analog direct current Iz into corresponding digital signals and sends the digital signals to the microcontroller module.
S6: the microcontroller module calculates according to an impedance fitting formula to obtain the impedance value val (x, y) measured by the channel at this time and stores the value val (x, y) in a buffer area of a corresponding channel in the MCU; at the same time, the counter value is incremented by 1.
The number of times of storing the impedance value is set uniformly in the buffer area of each channel, for example, 10 times of storing the impedance value is set, and when the number of times of storing the impedance value exceeds the set number of times, the buffer area of each channel updates the stored impedance value according to the first-in first-out principle.
The impedance calculation process of the current measurement channel is as follows:
First, the average value of the voltage and the current is calculated, respectively. According to the M sampling results, the voltage average vz_avg and the current average iz_avg are respectively:
Vz_avg＝(Vz1+Vz2+Vz3+……+Vzm)/M (1)
Iz_avg＝(Iz1+Iz2+Iz3+……+Izm)/M (2)
wherein, vz1, vz2, vz3, … … and Vzm are respectively the direct current voltage values obtained by M times of sampling; iz1, iz2, iz3, … …, izm are the direct current values obtained by M samples, respectively.
Second, calculate the direct impedance value x:
x＝Vz_avg/Iz_avg (3)
thirdly, calculating the impedance value val (x, y) of the current measurement according to an impedance fitting formula:
val(x,y)＝p00+(p10*x)+(p01*y)+(p20*x2)+(p11*x*y)+(p30*x3)+(p21*x2*y) (4)
wherein x is the direct impedance value of the current measurement; y is a first DCP value; p00, p10, p01, p20, p11, p30, p21 are p coefficients, obtained by polynomial fitting of a large number of test data. When the second DCP value is 20, the p coefficient is as shown in table 1.
TABLE 1
| Coefficient of p | Value (Range) |
| p00 | －102.7(－104.1～－101.4) |
| p10 | 448.6(445.6～451.6) |
| p01 | 0.01481(0.001865～0.02776) |
| p20 | －301.4(－303.7～－299.2) |
| p11 | －0.03425(－0.05432～－0.01419) |
| p30 | 117.7(117.1～118.2) |
| p21 | 0.02582(0.01847～0.03316) |
The impedance fitting formula shown in the formula (4) is formed by performing multiple times of switching from a radio frequency mode to a measurement mode and performing fitting on a large number of acquired currents, voltage values and first DCP values under different second DCP values.
S7: judging whether the count value of the counter is equal to the number N of the channel units or not; when the count value is smaller than N, the step S4 is carried out to measure the next channel unit; when the count value is equal to N, the process proceeds to the next step.
S8: according to the measured multiple impedance values of each channel, calculating the current impedance average value of each channel, and displaying the impedance average value through a display. At the same time, the counter is cleared.
It should be noted that the plurality of impedance values of each channel refer to a plurality of measured values stored in the corresponding channel buffer in the MCU.
S9: and after the impedance measurement is finished, the channel radio frequency control module is switched from the measurement mode to the radio frequency mode, and the DCP value of each channel is restored to the first DCP value.
S10: judging whether the impedance measurement in the operation is finished or not; if the measurement is finished, the next step is carried out; if the next measurement is performed, the process proceeds to step S2.
S11: the impedance measurement operation is ended.
The biological impedance measuring method based on the multichannel radio frequency emission provided by the invention is described in detail above. Based on the bio-impedance measurement method, the embodiment of the invention further provides a bio-impedance measurement system adopting the method for multi-channel radio-frequency emission, which comprises a microcontroller module, an upper computer and at least one channel unit. Each channel unit comprises a channel radio frequency control module, a transformer, a current transformer, a voltage transformer, a first rectifying circuit, a second rectifying circuit, a first relay and an analog-to-digital conversion module.
Referring to fig. 1, the upper computer is connected with a microcontroller module, and the microcontroller module is respectively connected with each channel unit. In each channel unit, the output end of the channel radio frequency control module is connected with the input end of a transformer, the output end of the transformer is connected with the input end of a first relay through a current transformer and a voltage transformer, and the output end of the first relay is connected with an electrode which is closely attached to biological tissues; the output ends of the current transformer and the voltage transformer are respectively connected with the input end of the analog-to-digital conversion module through the first rectifying circuit and the second rectifying circuit, the output end of the analog-to-digital conversion module is connected with the input end of the microcontroller module, the first output end of the microcontroller module is connected with the control end of the channel radio frequency control module, and meanwhile, the second output end of the microcontroller module is connected with the control end of the first relay.
The microcontroller module is used for controlling the working state of each channel unit, calculating according to the measurement result of the channel unit and finally obtaining the impedance average value. The upper computer is communicated with the microcontroller module and is used for supervising and controlling the measuring process of the biological impedance. The channel unit is used for generating and outputting radio frequency energy and measuring impedance of biological tissues.
The channel radio frequency control module in the channel unit comprises a signal generator, a signal amplifier, a digital potentiometer, a driving amplifier and a second relay. The output end of the signal generator is connected with the input end of the signal amplifier, the output end of the signal amplifier is connected with the input end of the digital potentiometer, the output end of the digital potentiometer is connected with the input end of the driving amplifier, and the output end of the driving amplifier is connected with the transformer in the channel unit; the first control signal end of the MCU is connected with the control end of the digital potentiometer, and the second control signal end of the MCU is connected with the control end of the second relay; the input end of the second relay is connected with the power supply end, and the output end of the second relay is connected with the power supply end of the driving amplifier.
The signal generator is used for generating a sine wave radio frequency signal with certain frequency and amplitude; the signal amplifier is used for amplifying the radio frequency signal; the digital potentiometer is used for adjusting the amplitude of the output radio frequency signal according to the MCU control signal; the driving amplifier is used for driving and amplifying the radio frequency signals; the second relay is used for controlling the on-off state of the working power supply of the driving amplifier according to the MCU control signal.
In summary, compared with the prior art, the bio-impedance measurement method based on multi-channel radio-frequency emission provided by the invention has the advantages that the micro-controller module is adopted to accurately control each channel unit, so that the measurement of each channel is acquired for multiple times under the same stable radio-frequency signal, the control, the acquisition and the feedback of each channel are all independent, the mutual interference among the channels is avoided, and the accurate measurement of the bio-impedance is realized. Meanwhile, the measuring system adopts the transformer, the analog-to-digital conversion module, the microcontroller module and other simpler and technically mature functional modules, so that the measuring system has the beneficial effects of good stability, low implementation cost, high reliability and the like.
It should be noted that the terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying a number of technical features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
The bio-impedance measurement method and the bio-impedance measurement system based on multi-channel radio-frequency emission provided by the invention are described in detail. Any obvious modifications to the present invention, without departing from the spirit thereof, would constitute an infringement of the patent rights of the invention and would take on corresponding legal liabilities.
Claims (8)
1. The biological impedance measurement method based on multichannel radio frequency emission is characterized by comprising the following steps of:
(1) Setting measurement related parameters, including at least the number of channel units used in the operation, the number of voltage and current acquisition times and a second DCP value of the channel;
(2) Judging whether an impedance measurement command is received or not; if a measurement command is received, the next step is carried out;
(3) The channel radio frequency control module is switched from a radio frequency mode to a measurement mode, and simultaneously, a first DCP value of each channel is recorded;
(4) Opening a measuring channel unit, and adjusting the DCP value of the channel to the set second DCP value; simultaneously, closing the rest channel units, and adjusting the DCP value of the closed channel to 0;
(5) The measuring channel unit sends out a radio frequency signal, and analog direct current voltage and analog direct current are obtained after the radio frequency signal is converted by a circuit; the analog-to-digital conversion module collects the analog direct-current voltage and the analog direct-current for a set number of times, converts the analog direct-current voltage and the analog direct-current into corresponding digital signals and sends the corresponding digital signals to the microcontroller module;
(6) The microcontroller module calculates according to an impedance fitting formula to obtain the impedance value measured by the channel at this time and stores the impedance value in a buffer area of a corresponding channel in the microcontroller module; meanwhile, the counter value is increased by 1;
(7) Judging whether the count value of the counter is equal to the set number of the channel units; when the count value is smaller than the set number of the channel units, the step (4) is carried out to measure the next channel unit; when the count value is equal to the set number of the channel units, the next step is carried out;
(8) Calculating the current impedance average value of each channel according to the measured multiple impedance values of each channel, and displaying the impedance average value through a display; meanwhile, the counter is cleared;
(9) The impedance measurement is finished, the channel radio frequency control module is switched from a measurement mode to a radio frequency mode, and the DCP value of each channel is restored to the first DCP value;
(10) Judging whether the impedance measurement in the operation is finished or not; if the measurement is finished, the next step is carried out; if the next measurement is carried out, the step (2) is carried out;
(11) The impedance measurement is ended.
2. The method of claim 1, wherein in step (6), the impedance value val (x, y) of the current measurement is calculated by the following formula:
val(x,y)＝p00+(p10*x)+(p01*y)+(p20*x2)+(p11*x*y)+(p30*x3)+(p21*x2*y)
Wherein x is the direct impedance value of the current measurement; y is a first DCP value; p00, p10, p01, p20, p11, p30, p21 are p coefficients.
3. The method for measuring bioimpedance based on multi-channel radio frequency transmission according to claim 2, wherein said direct impedance value x is calculated by the following formula:
x＝Vz_avg/Iz_avg
Where vz_avg is the voltage average and iz_avg is the current average.
4. The method for measuring bioimpedance based on multi-channel radio frequency emission according to claim 2, wherein when the second DCP value is set to 20, the p coefficient takes the following value:
p00＝－102.7；p10＝448.6；p01＝0.01481；p20＝－301.4；p11＝－0.03425；p30＝117.7；p21＝0.02582。
5. The method for measuring bioimpedance based on multi-channel radio frequency transmission according to claim 1, wherein in step (6):
The buffer area of each channel inside the microcontroller module is provided with unified times for storing the impedance value; when the number of times of storing the impedance value exceeds the set number of times, the cache area of each channel updates the stored impedance value according to the first-in first-out principle.
6. The bio-impedance measurement system based on multi-channel radio-frequency emission is characterized by comprising a microcontroller module, an upper computer and at least one channel unit; wherein,
The upper computer is connected with the microcontroller module and is used for supervising and controlling the measuring process of the biological impedance;
the microcontroller module is respectively connected with the channel units and used for controlling the working state of the channel units and calculating according to the measurement results of the channel units to finally obtain an impedance average value;
the channel unit is used for generating and outputting radio frequency energy and measuring impedance of biological tissues.
7. The multi-channel radio frequency emission based bioimpedance measurement system of claim 6, wherein:
Each channel unit comprises a channel radio frequency control module, a transformer, a current transformer, a voltage transformer, a first rectifying circuit, a second rectifying circuit, a first relay and an analog-to-digital conversion module; wherein,
The output end of the channel radio frequency control module is connected with the input end of the transformer, the output end of the transformer is connected with 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 with an electrode which is closely attached to biological tissues; the output ends of the current transformer and the voltage transformer are respectively connected with the input end of the analog-to-digital conversion module through the first rectifying circuit and the second rectifying circuit, the output end of the analog-to-digital conversion module is connected with the input end of the microcontroller module, the first output end of the microcontroller module is connected with the control end of the channel radio frequency control module, and meanwhile, the second output end of the microcontroller module is connected with the control end of the first relay.
8. The multi-channel radio frequency emission based bioimpedance measurement system of claim 7, wherein:
The channel radio frequency control module comprises a signal generator, a signal amplifier, a digital potentiometer, a driving amplifier and a second relay; wherein,
The output end of the signal generator is connected with the input end of the signal amplifier, the output end of the signal amplifier is connected with the input end of the digital potentiometer, the output end of the digital potentiometer is connected with the input end of the driving amplifier, and the output end of the driving amplifier is connected with the transformer in the channel unit;
The first control signal end of the microcontroller module is connected with the control end of the digital potentiometer, and the second control signal end of the microcontroller module is connected with the control end of the second relay; the input end of the second relay is connected with the power supply end, and the output end of the second relay is connected with the power supply end of the driving amplifier.
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