Method for stably collecting human body acupoint physiological information

Abstract

The invention relates to a system and method for stably collecting human body acupoint physiological information. The system is composed of a signal generation module, an acquisition amplification module, a DSP module and a CPU control module. The CPU control module is based on a main control unit in the FPGA chip, fast switching of analog switch channels is controlled according to instructions of an upper computer, the FIFO extracts impedance spectrum data of the DSP processing unit, an interface forwards the impedance spectrum data to the upper computer for Cole-Cole fitting, and physiological information of the acupuncture point resistance value of the human body is obtained.

Description

Technical Field

[0001] This invention relates to the field of bioelectrical impedance measurement, specifically to a method for stably acquiring physiological information from human acupoints. Background Technology

[0002] The principle of bioelectrical impedance analysis (BIA) involves applying alternating current signals of different frequencies to the human body surface. At low frequencies, the cell membrane exhibits capacitance-like characteristics, meaning the current can only flow through the extracellular fluid to form a circuit. The capacitance of the cell membrane decreases as the frequency of the excitation signal increases, allowing the excitation current signal to pass through the cell membrane and flow through the intracellular fluid. Based on this characteristic, the electrophysiological properties of biological tissues can be viewed as... Figure 1 The equivalent circuit model is shown.

[0003] Where Rt is the intracellular fluid resistance, Re is the extracellular fluid resistance, and Cm is the cell membrane capacitance. For example... Figure 1 As shown, combining the publicly available formulas for solving electrical impedance and the characteristic equation of electrical impedance, its principle and model have been widely verified and applied in the field of bioelectrical impedance measurement. Calculations show that the equivalent model of human biological tissue follows a circular arc trajectory as the frequency changes. By calculating the position of the center and the radius of the circle, the intracellular and extracellular fluid resistance and cell membrane capacitance values ​​can be obtained.

[0004] The four-electrode measurement method is a classic approach to eliminate contact resistance and interference from influencing resistance. It is widely used in bioanalytical measurements such as human body composition analysis and acupoint monitoring. The four-electrode measurement method consists of a pair of excitation electrodes and a pair of measurement electrodes. The excitation electrodes input a sweeping frequency signal with a constant amplitude to the measurement site on the human body, and the measurement electrodes collect the feedback signal from the measured site.

[0005] In practical application, the two bioelectrical impedance measurement methods mentioned above have certain drawbacks: First, the impedance values ​​are easily affected by factors such as changes in body hydration, thus affecting the accuracy of the final measurement. Second, the general algorithm is difficult to adapt to different conditions; the four-electrode method only measures the lower limbs and requires model fitting. Third, the operation is easily affected by external environmental and operational factors, such as skin temperature and humidity, electrode contact degree, muscle fatigue after exercise, or eating status. Furthermore, although the four-electrode method reduces contact resistance interference, the polarization between the electrode and tissue can still introduce errors in high-frequency measurements. Additionally, the multi-frequency scanning process increases the complexity and cost of the equipment and poses safety hazards such as cell membrane capacitance effects.

[0006] In summary, this method provides a stable way to collect physiological information of human acupoints that is simple in structure, accurate in measurement, has a high safety factor, and is easy to operate, and has broad market prospects. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for stably collecting physiological information of human acupoints that is simple in structure, accurate in measurement, has a high safety factor, and is easy to operate, thereby overcoming the deficiencies in existing technologies.

[0008] The technical solution of the present invention is implemented as follows: a system for stably acquiring physiological information of human acupoints, the system comprising a signal generation module, a constant current source module, an acquisition and amplification module, a DSP module and a CPU control module.

[0009] Furthermore, the signal generation module applies a continuously varying microampere-level AC signal to the part under test. The signal generation module includes a continuously varying frequency signal output module composed of a phase accumulator, a waveform lookup table, a digital-to-analog converter, and a reconstruction filter.

[0010] Furthermore, the constant current source module maintains a stable effective current value even when the input signal frequency and load size change.

[0011] Furthermore, the acquisition and amplification module performs differential amplification processing on the signals at both ends of the measurement electrode.

[0012] Furthermore, the DSP module processes the frequency of the signal after it has been processed by the acquisition and amplification module to obtain the real and imaginary parts of the human acupoint physiological information in the impedance diagram.

[0013] Furthermore, the CPU control module receives the output information from the DSP module and forwards it to the host computer for Cole-cole fitting to obtain stable physiological information of human acupoints.

[0014] A method for stably collecting physiological information of human acupoints as described above, the method comprising the following steps:

[0015] S1. Generate excitation signal

[0016] The signal generation module generates a linearly growing phase sequence through a phase accumulator. The digital phase sequence is then fed into a waveform lookup table to be mapped to the corresponding digital amplitude sequence, and converted into a stepped analog signal by a digital-to-analog converter. Finally, a reconstruction filter is used to smooth and filter out a clean sweep sine wave with a frequency that changes continuously with time within a specified range.

[0017] S2, Sweep Frequency Constant Current Output

[0018] The sweep frequency signal is then input to the differential constant current source circuit, which accurately converts the voltage of the input sweep frequency AC signal into a microampere-level output current that is not affected by the load resistance, and finally applies it to the human body part to be tested through the excitation electrode.

[0019] S3, Signal Sampling Amplification

[0020] The acquisition and amplification module adopts a three-op-amp instrumentation amplifier structure. Through the input stage composed of A1 and A2, the differential signal is accurately amplified by the gain resistor Rg and the common-mode voltage is output. Then, the common-mode noise is canceled by the subtractor composed of A3, and finally the pure single-ended voltage with ground reference is output.

[0021] S4. Constructing the impedance spectrum

[0022] The DSP module performs anti-aliasing filtering and analog-to-digital conversion on the amplified signal, and then performs discrete Fourier transform. Under the synchronization of the system clock, the signal passes through multiple cascaded butterfly operation units. After all the operations, the output data stream is the frequency domain representation of the signal. Each frequency component is output in complex form, thus constructing the impedance spectrum of the acquired signal.

[0023] S5. Processing physiological information from human acupoints

[0024] The CPU control module is based on the main control unit in the FPGA chip. According to the instructions of the host computer, it controls the rapid switching of the analog switch channel, extracts the impedance spectrum data of the DSP processing unit through FIFO, and forwards the data to the host computer through the interface for Cole-cole fitting to obtain the physiological information of the resistance value of acupoints in the human body.

[0025] The present invention has the following positive effects:

[0026] 1. Based on the four-electrode measurement principle, this invention employs DDS technology to generate a continuous sinusoidal signal. This signal, output by a differential constant current source circuit, has an effective value in the microampere range, ensuring measurement safety and the linear response of biological tissues. The microampere-level signal is far below the human perception threshold and neuromuscular excitation threshold, strictly avoiding electrophysiological risks and meeting medical device safety standards. More importantly, this level of current forces the operating point into the linear range of tissue impedance, avoiding tissue polarization, thermal effects, and nonlinear distortion caused by large currents. Therefore, the obtained complex impedance data more accurately reflects the intrinsic electrical characteristics of the tissue. Furthermore, weak signals are more sensitive to distributed capacitance and dielectric relaxation phenomena, helping to resolve fine dispersion characteristics related to tissue structure and functional state at multiple frequency points. This provides a higher signal-to-noise ratio and a more reliable raw data foundation for impedance spectrum studies of meridians.

[0027] 2. This invention differentially amplifies the weak response signals from acupoints, completely overcoming the influence of contact resistance on the measurement signal. This technology can accurately extract physiological information, and the measurement results have high consistency and reproducibility. Under the premise that the subject's physiological state is stable, repeatable data can be obtained multiple times. This feature significantly enhances the reliability of the measurement results and the professional authority of the product.

[0028] 3. This invention achieves intelligent control. The CPU module realizes parameterized control of the sweep frequency signal, rapid switching of detection sites and data forwarding. In conjunction with the host computer, it completes Cole-cole fitting, and can complete the scanning and detection of all twelve meridians of the human body within 2 minutes, improving detection efficiency and accuracy.

[0029] 4. This invention integrates signal processing and overall control circuitry through a highly integrated system-on-a-chip design. This fundamentally eliminates the high-cost, environmentally demanding discrete architecture required by traditional lock-in amplifiers, achieving dual optimization in cost and size. Thanks to the high integration of the core circuitry and the simplification of peripheral components, the device possesses excellent environmental robustness and portability. This feature greatly expands the product's application scenarios, enabling it to serve resource-scarce areas such as rural villages and grassroots communities, providing a reliable and easily deployable technical path for inclusive health monitoring.

[0030] The system and method of this invention quantify the physiological state of human acupoints through impedance spectroscopy data, providing an objective and standardized detection method for diagnosis. Attached Figure Description

[0031] Figure 1 This is a diagram of the existing technology for the equivalent circuit model.

[0032] Figure 2 This is a schematic diagram of the system and method steps of the present invention. Detailed Implementation

[0033] 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, and 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.

[0034] In the following description of the invention, it should be noted that the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. The term "connection" simply indicates a connection between devices and has no special meaning.

[0035] For specific embodiments, please refer to Figure 2As shown, a system for stably acquiring physiological information from human acupoints is described. This system comprises a signal generation module, a constant current source module, an acquisition and amplification module, a DSP module, and a CPU control module. The signal generation module applies a continuously varying microampere-level AC signal to the measurement site. This module includes a continuously varying frequency signal output module composed of a phase accumulator, a waveform lookup table, a digital-to-analog converter, and a reconstruction filter. The constant current source module maintains a stable effective current value despite changes in the input signal frequency and load. The acquisition and amplification module performs differential amplification on the signal across the measuring electrodes. The DSP module processes the frequency of the signal after acquisition and amplification to obtain the real and imaginary parts of the human acupoint physiological information in the impedance diagram. The CPU control module receives the output information from the DSP module and forwards it to the host computer for Cole-Cole fitting to obtain stable human acupoint physiological information.

[0036] A method for stably collecting physiological information from human acupoints, comprising the following steps:

[0037] S1. Generate excitation signal

[0038] The signal generation module generates a linearly growing phase sequence through a phase accumulator. The digital phase sequence is then fed into a waveform lookup table to be mapped to the corresponding digital amplitude sequence, and converted into a stepped analog signal by a digital-to-analog converter. Finally, a reconstruction filter is used to smooth and filter out a clean sweep sine wave with a frequency that changes continuously with time within a specified range.

[0039] S2, Sweep Frequency Constant Current Output

[0040] The sweep frequency signal is then input to the differential constant current source circuit, which accurately converts the voltage of the input sweep frequency AC signal into a microampere-level output current that is not affected by the load resistance, and finally applies it to the human body part to be tested through the excitation electrode.

[0041] S3, Signal Sampling Amplification

[0042] The acquisition and amplification module adopts a three-op-amp instrumentation amplifier structure. Through the input stage composed of A1 and A2, the differential signal is accurately amplified by the gain resistor Rg and the common-mode voltage is output. Then, the common-mode noise is canceled by the subtractor composed of A3, and finally the pure single-ended voltage with ground reference is output.

[0043] S4. Constructing the impedance spectrum

[0044] The DSP module performs anti-aliasing filtering and analog-to-digital conversion on the amplified signal, and then performs discrete Fourier transform. Under the synchronization of the system clock, the signal passes through multiple cascaded butterfly operation units. After all the operations, the output data stream is the frequency domain representation of the signal. Each frequency component is output in complex form, thus constructing the impedance spectrum of the acquired signal.

[0045] S5. Processing physiological information from human acupoints

[0046] The CPU control module is based on the main control unit in the FPGA chip. According to the instructions of the host computer, it controls the rapid switching of the analog switch channel, extracts the impedance spectrum data of the DSP processing unit through FIFO, and forwards the data to the host computer through the interface for Cole-cole fitting to obtain the physiological information of the resistance value of acupoints in the human body.

[0047] Example 1: In the specific implementation of the human acupoint physiological information acquisition operation, the signal generation module works in concert with a phase accumulator, waveform lookup table, digital-to-analog converter, and reconstruction filter to achieve high-precision frequency synthesis. The resulting frequency-sweeping AC signal, with a constant current output from a differential constant current source, is then applied to the corresponding human response site via excitation electrodes. The core of this process involves using a stable reference clock to drive the phase accumulator, generating a time-base phase sequence by cyclically accumulating the frequency control word. The high-order address code of this phase sequence is used to address the waveform lookup table, thereby converting discrete phase information into corresponding waveform amplitude sample values. Subsequently, the digital-to-analog converter reconstructs these digital sample values ​​into a stepped analog signal. Finally, after anti-mirror filtering and smoothing, a clean frequency-sweeping continuous signal with the required frequency and waveform is output. The frequency-sweeping signal is input to the differential constant current source circuit. This circuit includes an operational amplifier-based negative feedback circuit. Through a resistor network configuration, an inverting circuit is introduced from one end of the load resistor and connected to the other end, accurately converting the voltage of the input frequency-sweeping AC signal into an output current unaffected by the load resistor. This current is then applied to both ends of the detection site via excitation electrodes.

[0048] The acquisition and amplification circuit uses a three-op-amp instrumentation amplifier structure to differentially amplify the signal across the measurement electrodes. The signal is input from the non-inverting (IN+) and inverting (IN-) input terminals and processed by an input stage consisting of two precision operational amplifiers, A1 and A2. The outputs of the two op-amps are connected via an external single-gain setting resistor Rg. Based on the virtual short and virtual open principles, the differential input voltage primarily drops across Rg, generating a current. This current flows through the feedback network of A1 and A2, precisely setting the gain of the first stage. The first stage amplifies the input differential voltage and transmits it to its output as a common-mode voltage. This common-mode voltage contains both the original input common-mode component and the amplified differential signal. The output of the first stage is fed into a subtractor circuit consisting of a third operational amplifier A3. Since any identical common-mode noise or DC bias will appear on both Vout1 and Vout2, they will be completely canceled out in an ideal subtraction operation. Finally, A3 converts the pure differential signal pre-amplified by the first stage into a clean, single-ended output voltage referenced to ground.

[0049] The DSP module first passes the input signal, processed by the sampling amplification circuit, through an anti-aliasing filter and then performs analog-to-digital conversion to obtain a digital sequence. This sequence is then fed into the front end of the FFT processor, where, synchronized with the system clock, it undergoes core computation through a multi-stage cascaded butterfly arithmetic unit. Each stage of computation involves complex multiplication and addition operations, with multipliers derived from twiddle factors pre-stored in block memory. The entire process employs pipelined technology, allowing the data stream to be processed continuously, thus achieving extremely high throughput. After all stages of computation, the output data stream is the frequency domain representation of the signal. Each frequency component is output in complex form, meaning that the Fourier coefficients of the target signal at a single frequency point are calculated in the continuous time domain, yielding the real and imaginary parts of the human acupoint physiological information in the impedance diagram.

[0050] The CPU control module is responsible for responding to the operation instructions of the host computer, driving the signal generation module to output a frequency sweep signal within a preset frequency range, controlling the analog switch chip to quickly switch between different detection sites, and finally receiving the output information from the DSP module and forwarding it to the host computer for Cole-cole fitting to obtain accurate and stable physiological information of human acupoints.

[0051] To test the reproducibility of the measurement results of the testing equipment, the table below shows the test results of the same subject at three different times. The first and second tests were 12 hours apart, and the first and third tests were 24 hours apart. The measurement environment was kept consistent each time, and the extracellular fluid values ​​of all twelve meridians and a total of 24 acupoints were recorded for each measurement. It can be seen that the test results of the present invention have high reproducibility when the human body is in a stable state.

[0052]

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A system for stably collecting physiological information from human acupoints, characterized in that: The system consists of a signal generation module, a constant current source module, an acquisition and amplification module, a DSP module, and a CPU control module.

2. The stable acquisition system for human acupoint physiological information according to claim 1, characterized in that: The signal generation module applies a continuously varying microampere-level AC signal to the part under test. The signal generation module includes a continuously varying frequency signal output module composed of a phase accumulator, a waveform lookup table, a digital-to-analog converter, and a reconstruction filter.

3. The stable acquisition system for human acupoint physiological information according to claim 1, characterized in that: The constant current source module maintains a stable effective current value despite changes in input signal frequency and load size.

4. The stable acquisition system for human acupoint physiological information according to claim 1, characterized in that: The acquisition and amplification module performs differential amplification processing on the signals at both ends of the measuring electrode.

5. The stable acquisition system for human acupoint physiological information according to claim 1, characterized in that: The DSP module processes the frequency of the signal after it has been processed by the acquisition and amplification module to obtain the real and imaginary parts of the human acupoint physiological information in the impedance diagram.

6. The system for stably collecting physiological information from human acupoints according to claim 1, characterized in that: The CPU control module receives the output information from the DSP module and forwards it to the host computer for Cole-cole fitting to obtain stable physiological information of human acupoints.

7. A method for stably collecting physiological information of human acupoints as described in any one of claims 1-5, characterized in that, The method includes the following steps: S1. Generate excitation signal The signal generation module generates a linearly growing phase sequence through a phase accumulator. The digital phase sequence is then fed into a waveform lookup table to be mapped to the corresponding digital amplitude sequence, and converted into a stepped analog signal by a digital-to-analog converter. Finally, a reconstruction filter is used to smooth and filter out a clean sweep sine wave with a frequency that changes continuously with time within a specified range. S2, Sweep Frequency Constant Current Output The sweep frequency signal is then input to the differential constant current source circuit, which accurately converts the voltage of the input sweep frequency AC signal into a microampere-level output current that is not affected by the load resistance, and finally applies it to the human body part to be tested through the excitation electrode. S3, Signal Sampling Amplification The acquisition and amplification module adopts a three-op-amp instrumentation amplifier structure. Through the input stage composed of A1 and A2, the differential signal is accurately amplified by the gain resistor Rg and the common-mode voltage is output. Then, the common-mode noise is canceled by the subtractor composed of A3, and finally the pure single-ended voltage with ground reference is output. S4. Constructing the impedance spectrum The DSP module performs anti-aliasing filtering and analog-to-digital conversion on the amplified signal, and then performs discrete Fourier transform. Under the synchronization of the system clock, the signal passes through multiple cascaded butterfly operation units. After all the operations, the output data stream is the frequency domain representation of the signal. Each frequency component is output in complex form, thus constructing the impedance spectrum of the acquired signal. S5. Processing physiological information from human acupoints The CPU control module is based on the main control unit in the FPGA chip. According to the instructions of the host computer, it controls the rapid switching of the analog switch channel, extracts the impedance spectrum data of the DSP processing unit through FIFO, and forwards the data to the host computer through the interface for Cole-cole fitting to obtain the physiological information of the resistance value of acupoints in the human body.

Images