An electrical stimulation system for real-time monitoring of impedance

Abstract

The application discloses a kind of real-time monitoring impedance electric stimulation system, belong to medical electronic technical field;The system includes signal generation module, signal multiplexing module, signal acquisition module, impedance extraction module, impedance calculation module and intelligent feedback control module;Signal generation module simultaneously generates treatment stimulation signal and frequency orthogonal impedance monitoring signal;Signal multiplexing module is combined after two kinds of signals and is applied to human body by electrode;Signal acquisition module acquires mixed signal containing physiological response and impedance information;Impedance extraction module accurately extracts impedance modulation component from mixed signal using digital lock-in amplification technology;Impedance calculation module calculates electrode-tissue contact impedance in real time;Intelligent feedback control module carries out multistage threshold judgment according to impedance value, realizes alarm, parameter adjustment and safety protection function;The application realizes the synchronization of treatment and monitoring, improves the safety and reliability of system, is applicable to various electric stimulation medical equipment.

Description

Technical Field

[0001] This invention belongs to the field of medical electronics technology, specifically relating to an electrical stimulation system for real-time impedance monitoring. Background Technology

[0002] Electrical stimulation technology has been widely used in the treatment and rehabilitation of neurological diseases, such as deep brain stimulation for Parkinson's disease, spinal cord stimulation for chronic pain, and functional electrical stimulation for motor dysfunction. In these applications, the contact impedance between the electrode and biological tissue is a key parameter affecting the stimulation effect and safety. Excessive impedance can prevent the stimulation current from being effectively transmitted, reducing the therapeutic effect; sudden impedance changes may indicate electrode detachment, tissue damage, or equipment malfunction, posing safety risks.

[0003] Existing electrical stimulation systems typically employ intermittent impedance measurement methods, which involve performing single impedance measurements during treatment breaks or when the device is activated. This method has the following drawbacks: First, it cannot track dynamic changes in impedance in real time during treatment, potentially missing critical abnormal events; second, the measurement process requires pausing or interrupting treatment stimulation, affecting the continuity of treatment; third, the measurement signal and treatment signal are time-division multiplexed, resulting in a slow system response and an inability to promptly detect and handle emergencies. Summary of the Invention

[0004] This invention addresses the shortcomings of existing electrostimulation systems, such as the inability to monitor impedance in real time, interference with treatment signals during monitoring, and lack of intelligent feedback control. It provides an electrostimulation system that monitors impedance in real time, achieving simultaneous treatment stimulation and impedance monitoring through frequency orthogonal multiplexing technology. Digital phase-locked amplification technology is used to accurately extract impedance information, ensuring the safety and effectiveness of treatment.

[0005] The solution of the present invention is as follows: An electrical stimulation system for real-time impedance monitoring, wherein the system comprises, in sequence, a signal generation module, a signal multiplexing module, a signal acquisition module, an impedance extraction module, an impedance calculation module, and an intelligent feedback control module.

[0006] The signal generation module is used to simultaneously generate physiological stimulation signals and impedance monitoring signals. The frequency range of the impedance monitoring signals is 1kHz-10kHz, and its frequency components are orthogonal to the frequency band of the physiological stimulation signals.

[0007] The signal multiplexing module is used to combine the physiological stimulation signal and the impedance monitoring signal and apply them to the human body through electrodes.

[0008] The signal acquisition module is used to acquire a mixed signal by recording electrodes, the mixed signal including induced physiological response, environmental noise and impedance monitoring signal.

[0009] The signal separation module is used to filter the mixed signal and separate the impedance monitoring signal frequency band.

[0010] The impedance extraction module is used to extract the impedance-modulated monitoring signal from the separated signal by lock-in amplification, using the original impedance monitoring signal as a reference signal.

[0011] The impedance calculation module is used to calculate the electrode-skin contact impedance value of each channel in real time based on the extracted monitoring signal.

[0012] The intelligent feedback control module is used to determine the status based on the real-time monitored impedance value, and to issue an alarm or adjust the stimulation parameters when the impedance exceeds a preset threshold.

[0013] Furthermore, the signal multiplexing module includes an adder circuit, an isolation circuit, and a driver amplifier; the adder circuit is used to linearly superimpose the physiological stimulation signal and the impedance monitoring signal; the isolation circuit includes a series coupling capacitor. and current limiting resistor The coupling capacitor The capacitance range is 0.1μF-10μF, and the current-limiting resistor... The resistance range is 100Ω-10kΩ, which is used to ensure that the impedance monitoring signal does not affect the output characteristics of the physiological stimulation signal.

[0014] Furthermore, the drive amplifier is used to amplify the power of the combined signal and output it to the electrode through a constant current source circuit. The output current control formula of the constant current source circuit is as follows: In the formula, The output current (A) is the output current. The input voltage signal is (V). S is the transconductance gain. This is the feedback coefficient.

[0015] Furthermore, the signal separation module includes: at least one high-pass filter and a preamplifier; the cutoff frequency of the high-pass filter is set to: , The cutoff frequency (Hz) The center frequency (Hz) of the impedance monitoring signal. The highest frequency (Hz) of the physiological signal is required, and the isolation between the impedance monitoring signal band and the physiological signal band must be greater than 40dB.

[0016] Furthermore, the gain of the preamplifier is adaptively adjusted based on the expected attenuation of the impedance monitoring signal, and the gain adjustment formula is as follows: ; This represents the gain (dB) of the preamplifier. The reference signal voltage (V) is used. To measure signal voltage (V). This represents the bias gain (dB).

[0017] Furthermore, the impedance extraction module is implemented using a digital lock-in amplifier and includes: a mixer unit, an amplitude and phase calculation unit, a digital signal processing unit, and a phase impedance component calculation unit.

[0018] The mixer unit is used to orthogonally mix the separated signal with the reference signal to generate in-phase components. and orthogonal components : ; ; The impedance monitoring signal (V) is collected. The reference signal angular frequency (rad / s) The reference signal phase (rad) is denoted by LPF, and LPF is a low-pass filter.

[0019] The amplitude and phase calculation unit is used to calculate the amplitude of the impedance monitoring signal. and phase : ; ; The digital signal processing unit is used to filter and smooth the calculation results. The filtering algorithm uses a first-order IIR filter. ; This is a smoothing coefficient, with a value range of 0.8-0.95. This is the current measured amplitude.

[0020] Furthermore, the model expression for calculating the impedance value by the impedance calculation module is as follows: ; The electrode-skin contact resistance (Ω). The voltage amplitude (V) of the injected impedance monitoring signal. The amplitude of the reference signal when there is no impedance. The current (A) is the current of the impedance monitoring signal injected.

[0021] Furthermore, the phase impedance component calculation unit is used to decompose the resistive component of the impedance. and reactance component : ; The resistance component The reactance component reflects the pure resistivity characteristics. It reflects the characteristics of capacitance or inductance.

[0022] Furthermore, the intelligent feedback control module includes: a multi-level threshold judgment unit, an alarm control unit, an adaptive compensation unit, and a safety protection unit.

[0023] The multi-level threshold judgment unit is set with a first threshold. Second threshold and the third threshold ,in These correspond to three status levels: normal, warning, and danger.

[0024] The alarm control unit detected the impedance value. The corresponding alarm level is triggered when the corresponding conditions are met; if This triggers a Level 1 warning, displaying a yellow indicator; if If a level 2 warning is triggered, an audible alert will be issued; if This triggers a level three alarm, pausing or reducing stimulus output.

[0025] The adaptive compensation unit is used to adjust the impedance change rate. The signal acquisition gain is dynamically adjusted, and the compensation formula is as follows: ; The adjusted gain. For the current gain, For compensation coefficient, The change in impedance is expressed in Ω. The initial impedance value is (Ω).

[0026] The safety protection unit is used to detect impedance change rate that meets the following conditions. Immediately cut off the stimulus output, where The impedance change rate threshold (Ω / s).

[0027] The system also includes a quality assessment module for calculating the signal quality index based on impedance stability. : ; The standard deviation of the impedance value (Ω) is given. The average impedance value (Ω). The value ranges from 0 to 100, and the higher the value, the better the signal quality.

[0028] Furthermore, the signal generation module uses frequency synthesis technology to generate the impedance monitoring signal, including: a direct digital frequency synthesizer (DDS) for generating a programmable frequency sine wave signal or a pseudo-random noise sequence; and a frequency jump control unit for automatically adjusting the impedance monitoring signal frequency to avoid interference frequencies when power frequency interference is detected. The frequency adjustment strategy is as follows: ; The adjusted frequency (Hz). Set the initial frequency (Hz). For the number of jump steps, The frequency step size (Hz) is an integer multiple of 50Hz or 100Hz.

[0029] Furthermore, the system includes a display module for displaying the impedance values ​​of each channel and their dynamic changing trends in real time.

[0030] Furthermore, the system also includes a temperature compensation module for adjusting the ambient temperature. The impedance measurement value is corrected using the following formula: ; This is the corrected impedance value (Ω). The measured impedance value (Ω). This is a temperature coefficient, with a value ranging from 0.001 to 0.005 / ℃. For reference temperature, take 25℃.

[0031] Compared with the prior art, the beneficial effects of this invention are: This invention achieves simultaneous transmission of physiological stimulation signals and impedance monitoring signals through frequency orthogonal multiplexing technology, enabling continuous monitoring of electrode-tissue interface impedance without interrupting treatment. The digital lock-in amplification algorithm effectively suppresses physiological noise and environmental interference, improving impedance measurement accuracy. Multi-level threshold judgment and adaptive compensation mechanisms enable intelligent feedback control, allowing for timely detection of abnormalities and automatic parameter adjustment or triggering of safety protection. This significantly enhances the safety, reliability, and therapeutic effect of the electrical stimulation system, providing a superior technical solution for clinical applications. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of an electrical stimulation system for real-time impedance monitoring according to the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0034] like Figure 1The diagram shown is a schematic of the composition of an electrical stimulation system for real-time impedance monitoring according to the present invention. The system is sequentially connected to include: a signal generation module, a signal multiplexing module, a signal acquisition module, an impedance extraction module, an impedance calculation module, and an intelligent feedback control module.

[0035] The signal generation module is used to simultaneously generate physiological stimulation signals and impedance monitoring signals. The frequency range of the impedance monitoring signals is 1kHz-10kHz, and its frequency components are orthogonal to the frequency band of the physiological stimulation signals.

[0036] In this embodiment, the physiological stimulation signal is a biphasic symmetrical square wave pulse with a pulse width of 200 μs, a frequency of 20 Hz, and an amplitude range of 0-20 mA, which is suitable for transcutaneous electrical nerve stimulation (TENS) applications.

[0037] The signal generation module uses frequency synthesis technology to generate impedance monitoring signals, including: a direct digital frequency synthesizer (DDS) for generating a programmable frequency sine wave signal or a pseudo-random noise sequence; the DDS generates a sine wave signal with a center frequency of 5kHz and an amplitude of 100mV, which is much higher than the frequency band of the physiological stimulation signal (20Hz and its harmonic components are mainly concentrated in the range of 0-500Hz), ensuring that the two signal frequencies are orthogonal and do not interfere with each other.

[0038] The frequency switching control unit automatically adjusts the impedance monitoring signal frequency to avoid interference frequencies when power frequency interference is detected. For example, when high-order harmonic interference (e.g., 5kHz = 100 × 50Hz) is detected near 5kHz in a 50Hz power frequency interference, the system automatically adjusts the monitoring signal frequency to 5.1kHz or 4.9kHz to avoid the interference frequency. The frequency adjustment strategy is as follows: ; The adjusted frequency (Hz). Set the initial frequency (Hz). For the number of jump steps, The frequency step size (Hz) is an integer multiple of 50Hz or 100Hz.

[0039] The signal multiplexing module is used to combine the physiological stimulation signal and the impedance monitoring signal and apply them to the human body through electrodes.

[0040] The signal multiplexing module includes an adder circuit, an isolation circuit, and a driver amplifier; the adder circuit is used to linearly superimpose the physiological stimulation signal and the impedance monitoring signal; the isolation circuit includes a series coupling capacitor. and current limiting resistor The coupling capacitor The capacitance range is 0.1μF-10μF, and the current-limiting resistor... The resistance range is 100Ω-10kΩ, which is used to ensure that the impedance monitoring signal does not affect the output characteristics of the physiological stimulation signal.

[0041] The drive amplifier is used to amplify the power of the combined signal and outputs it to the electrode through a constant current source circuit. The output current control formula of the constant current source circuit is: In the formula, The output current (A) is the output current. The input voltage signal is (V). S is the transconductance gain. This is the feedback coefficient. In this embodiment, the transconductance gain... = 0.01 S, feedback coefficient β = 0.1, when input voltage When = 2V, the output current mA. The constant current source circuit ensures that the stimulation current remains constant regardless of changes in load impedance (electrode-skin contact impedance), avoiding inconsistent stimulation intensity due to impedance fluctuations.

[0042] The adder circuit uses an operational amplifier to linearly superimpose the physiological stimulation signal (a voltage signal with an amplitude of 0-20mA) and the impedance monitoring signal (100mV, 5kHz sine wave). The isolation circuit consists of a coupling capacitor C1 and a current-limiting resistor R1 connected in series. In this embodiment, C1 is a 1μF high-precision film capacitor, and R1 is a 1kΩ precision resistor. The capacitive reactance of the coupling capacitor at the 5kHz monitoring frequency is approximately 32Ω, which is much smaller than that of the current-limiting resistor, ensuring that the monitoring signal can pass through effectively. At the same time, in the physiological stimulation signal frequency band (20Hz), the capacitive reactance is as high as approximately 8kΩ, effectively blocking the influence of low-frequency stimulation signals on the monitoring signal.

[0043] The signal acquisition module is used to acquire a mixed signal through recording electrodes. The mixed signal includes induced physiological response, environmental noise, and impedance monitoring signal. The signal contains three main components: induced physiological response (such as electromyographic signal, neural response, etc., frequency range 10Hz-500Hz), environmental noise (power frequency interference 50Hz / 60Hz and its harmonics), and impedance monitoring signal (a 5kHz sine wave modulated by electrode-skin impedance). The acquisition circuit uses a low-noise instrumentation amplifier with a gain set to 40dB, input impedance >10MΩ, common-mode rejection ratio >100dB, and sampling rate set to 50kHz, satisfying the Nyquist sampling theorem requirements.

[0044] The signal separation module is used to filter the mixed signal and separate the impedance monitoring signal frequency band.

[0045] The signal separation module includes: at least one high-pass filter and a preamplifier; the cutoff frequency of the high-pass filter is set to: , The cutoff frequency (Hz) The center frequency (Hz) of the impedance monitoring signal. The highest frequency (Hz) of the physiological signal is required, and the isolation between the impedance monitoring signal band and the physiological signal band must be greater than 40dB.

[0046] The gain of the preamplifier is adaptively adjusted based on the expected attenuation of the impedance monitoring signal, and the gain adjustment formula is as follows: ; This represents the gain (dB) of the preamplifier. Reference signal voltage (V) = 100mV, To measure signal voltage (V). This represents the bias gain (dB).

[0047] The impedance extraction module is implemented using a digital lock-in amplifier and includes: a mixer unit, an amplitude and phase calculation unit, a digital signal processing unit, and a phase impedance component calculation unit.

[0048] The mixer unit is used to orthogonally mix the separated signal with the reference signal to generate in-phase components. and orthogonal components : ; ; The impedance monitoring signal (V) is collected. The reference signal angular frequency (rad / s) The reference signal phase (rad) is denoted by LPF, and LPF is a low-pass filter.

[0049] The amplitude and phase calculation unit is used to calculate the amplitude of the impedance monitoring signal. and phase : ; ; The digital signal processing unit is used to filter and smooth the calculation results. The filtering algorithm uses a first-order IIR filter. ; This is a smoothing coefficient, with a value range of 0.8-0.95. This is the current measured amplitude.

[0050] The impedance extraction module is used to extract the impedance-modulated monitoring signal from the separated signal by lock-in amplification, using the original impedance monitoring signal as a reference signal.

[0051] The impedance calculation module is used to calculate the electrode-skin contact impedance value of each channel in real time based on the extracted monitoring signal. The model expression for calculating the impedance value by the impedance calculation module is: ; The electrode-skin contact resistance (Ω). The voltage amplitude (V) of the injected impedance monitoring signal. The amplitude of the reference signal when there is no impedance. The current (A) is the current of the impedance monitoring signal injected.

[0052] The phase impedance component calculation unit is used to decompose the resistive component of the impedance. and reactance component : ; The resistance component The reactance component reflects the pure resistivity characteristics. It reflects the characteristics of capacitance or inductance.

[0053] The intelligent feedback control module is used to determine the status based on the real-time monitored impedance value, and to issue an alarm or adjust the stimulation parameters when the impedance exceeds a preset threshold.

[0054] The intelligent feedback control module includes: a multi-level threshold judgment unit, an alarm control unit, an adaptive compensation unit, and a safety protection unit.

[0055] The multi-level threshold judgment unit is set with a first threshold. Second threshold and the third threshold ,in These correspond to three status levels: normal, warning, and danger. The first threshold Z1 = 500Ω, the second threshold Z2 = 1000Ω, and the third threshold Z3 = 2000Ω. These thresholds are determined based on clinical experience and actual application needs and can be adjusted according to different application scenarios.

[0056] The alarm control unit detected the impedance value. The corresponding alarm level is triggered when the corresponding conditions are met; if This triggers a Level 1 warning, displaying a yellow indicator; if If a level 2 warning is triggered, an audible alert will be issued; if This triggers a level three alarm, pausing or reducing stimulus output.

[0057] The adaptive compensation unit is used to adjust the impedance change rate. The signal acquisition gain is dynamically adjusted, and the compensation formula is as follows: ;: The adjusted gain. For the current gain, For compensation coefficient, The change in impedance is expressed in Ω. The initial impedance value is (Ω).

[0058] The safety protection unit is used to detect impedance change rate that meets the following conditions. Immediately cut off the stimulus output, where The impedance change rate threshold (Ω / s) is used. In this embodiment, the threshold Vth = 500Ω / s, meaning that when the impedance changes by more than 500Ω within 1 second, the system determines it as an abnormal sudden change (possibly due to electrode detachment, wire breakage, etc.) and immediately cuts off the stimulation to avoid safety hazards. For example, if the impedance suddenly changes from 200Ω to 300Ω within 0.1 seconds, the safety protection is triggered.

[0059] The system also includes a quality assessment module for calculating the signal quality index based on impedance stability. : ; The standard deviation of the impedance value (Ω) is given. The average impedance value (Ω). The value ranges from 0 to 100, and the higher the value, the better the signal quality.

[0060] The system includes a display module for displaying the impedance values ​​of each channel and their dynamic changing trends in real time.

[0061] The system also includes a temperature compensation module, used to adjust the temperature according to the ambient temperature. The impedance measurement value is corrected using the following formula: ; This is the corrected impedance value (Ω). The measured impedance value (Ω). This is a temperature coefficient, with a value ranging from 0.001 to 0.005 / ℃. For reference temperature, take 25℃.

[0062] This system can continuously and accurately monitor electrode-tissue contact impedance without interrupting treatment, and achieve intelligent feedback control and safety protection based on impedance changes, providing reliable technical support for clinical electrical stimulation therapy.

[0063] This invention has been described through specific embodiments. Those skilled in the art will understand that various modifications and equivalent substitutions can be made to this invention without departing from its scope. Furthermore, various modifications can be made to this invention for specific situations or materials without departing from its scope. Therefore, this invention is not limited to the specific embodiments disclosed, but should include all embodiments falling within the scope of the claims.

Claims

1. An electrical stimulation system for monitoring impedance in real time, characterized by, The system is sequentially connected to the following modules: a signal generation module, a signal multiplexing module, a signal acquisition module, an impedance extraction module, an impedance calculation module, and an intelligent feedback control module. The signal generation module is used to simultaneously generate physiological stimulation signals and impedance monitoring signals. The frequency range of the impedance monitoring signals is 1kHz-10kHz, and their frequency components are orthogonal to the frequency band of the physiological stimulation signals. The signal multiplexing module is used to combine the physiological stimulation signal and the impedance monitoring signal and apply them to the human body through electrodes. The signal acquisition module is used to acquire a mixed signal by recording electrodes, the mixed signal including induced physiological response, environmental noise and impedance monitoring signal; The signal separation module is used to filter the mixed signal and separate the impedance monitoring signal frequency band; The impedance extraction module is used to extract the impedance-modulated monitoring signal from the separated signal by lock-in amplification, using the original impedance monitoring signal as a reference signal. The impedance calculation module is used to calculate the electrode-skin contact impedance value of each channel in real time based on the extracted monitoring signal. The intelligent feedback control module is used to determine the status based on the real-time monitored impedance value, and to issue an alarm or adjust the stimulation parameters when the impedance exceeds a preset threshold.

2. The electrical stimulation system for real-time impedance monitoring according to claim 1, characterized in that, The signal multiplexing module includes an adder circuit, an isolation circuit, and a driver amplifier; The adder circuit is used to linearly superimpose the physiological stimulation signal and the impedance monitoring signal; The isolation circuit includes coupling capacitors connected in series. and current limiting resistor The coupling capacitor The capacitance range is 0.1μF-10μF, and the current-limiting resistor... The resistance range is 100Ω-10kΩ, which is used to ensure that the impedance monitoring signal does not affect the output characteristics of the physiological stimulation signal; The drive amplifier is used to amplify the power of the combined signal and outputs it to the electrode through a constant current source circuit. The output current control formula of the constant current source circuit is: In the formula, For output current, The input voltage signal is... For transconductance gain, This is the feedback coefficient.

3. The electrical stimulation system for real-time impedance monitoring according to claim 2, characterized in that, The signal separation module includes: at least one high-pass filter and a preamplifier; The high-pass filter cutoff frequency is set as follows: , The cutoff frequency, The center frequency of the impedance monitoring signal. The highest frequency of the physiological signal, wherein the isolation between the impedance monitoring signal band and the physiological signal band must be greater than 40dB; The gain of the preamplifier is adaptively adjusted based on the expected attenuation of the impedance monitoring signal, and the gain adjustment formula is as follows: ; This is the gain of the preamplifier. For reference signal voltage, To measure signal voltage, This is the bias gain.

4. The electrical stimulation system for real-time impedance monitoring according to claim 3, characterized in that, The impedance extraction module is implemented using a digital lock-in amplifier and includes: a mixer unit, an amplitude and phase calculation unit, a digital signal processing unit, and a phase impedance component calculation unit. The mixer unit is used to orthogonally mix the separated signal with the reference signal to generate in-phase components. and orthogonal components : ; ; For the acquired impedance monitoring signal, For the reference signal angular frequency, The reference signal phase is used, and LPF is a low-pass filter; The amplitude and phase calculation unit is used to calculate the amplitude of the impedance monitoring signal. and phase : ； ； The digital signal processing unit is used to filter and smooth the calculation results. The filtering algorithm uses a first-order IIR filter. ; This is a smoothing coefficient, with a value range of 0.8-0.

95. This is the current measured amplitude.

5. The electrical stimulation system for real-time impedance monitoring according to claim 4, characterized in that, The model expression for calculating the impedance value by the impedance calculation module is as follows: ; Electrode-skin contact resistance, The amplitude of the injected impedance monitoring signal voltage. The amplitude of the reference signal when there is no impedance. For the injected impedance monitoring signal current; The phase impedance component calculation unit is used to decompose the resistive component of the impedance. and reactance component : ; The resistance component The reactance component reflects the pure resistivity characteristics. It reflects the characteristics of capacitance or inductance.

6. The electrical stimulation system for real-time impedance monitoring according to claim 5, characterized in that, The intelligent feedback control module includes: a multi-level threshold judgment unit, an alarm control unit, an adaptive compensation unit, and a safety protection unit; The multi-level threshold judgment unit is set with a first threshold. Second threshold and the third threshold ,in These correspond to three status levels: normal, warning, and danger, respectively. The alarm control unit detected the impedance value. The corresponding alarm level is triggered when the corresponding conditions are met; if This triggers a Level 1 warning, displaying a yellow indicator; if If a level 2 warning is triggered, an audible alert will be issued; if This triggers a level three alarm, pausing or reducing the stimulation output; The adaptive compensation unit is used to adjust the impedance change rate. The signal acquisition gain is dynamically adjusted, and the compensation formula is as follows: ; The adjusted gain. For the current gain, For compensation coefficient, The change in impedance. This is the initial impedance value; The safety protection unit is used to detect impedance change rate that meets the following conditions. Immediately cut off the stimulus output, where This is the threshold for the rate of change of impedance.

7. The electrical stimulation system for real-time impedance monitoring according to claim 6, characterized in that, The system also includes a quality assessment module for calculating the signal quality index based on impedance stability. : ; The standard deviation of the impedance value. The average impedance value. The value ranges from 0 to 100, and the higher the value, the better the signal quality.

8. The electrical stimulation system for real-time impedance monitoring according to claim 7, characterized in that, The signal generation module uses frequency synthesis technology to generate an impedance monitoring signal, including: A direct digital frequency synthesizer (DDS) is used to generate sinusoidal signals or pseudo-random noise sequences with programmable frequencies. The frequency switching control unit is used to automatically adjust the frequency of the impedance monitoring signal to avoid interference frequencies when power frequency interference is detected; the frequency adjustment strategy is as follows: ; The adjusted frequency, To set the initial frequency, For the number of jump steps, This is the frequency step size, and its value is an integer multiple of 50Hz or 100Hz.

9. The electrical stimulation system for real-time impedance monitoring according to claim 8, characterized in that, The system includes a display module for displaying the impedance values ​​of each channel and their dynamic changing trends in real time.

10. The electrical stimulation system for real-time impedance monitoring according to claim 9, characterized in that, The system also includes a temperature compensation module, used to adjust the temperature according to the ambient temperature. The impedance measurement value is corrected using the following formula: ; This is the corrected impedance value. The measured impedance value, This is a temperature coefficient, with a value ranging from 0.001 to 0.005 / ℃. For reference temperature, take 25℃.

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