Multi-channel adjustable ac-dc nerve electrical stimulation device

Abstract

The application relates to the technical field of nerve electric stimulation, in particular to a multi-channel adjustable AC / DC nerve electric stimulation device, which comprises a main control module, a multi-channel peripheral nerve DC electric stimulation module and a multi-channel peripheral nerve AC electric stimulation module; wherein the multi-channel peripheral nerve DC electric stimulation module comprises a switch matrix module, a constant current driving module, an H-bridge commutation module and an overcurrent protection module; the multi-channel peripheral nerve DC electric stimulation module is used for generating a DC electric stimulation signal; the multi-channel peripheral nerve AC electric stimulation module comprises a signal generation module, a filter coupling module, a power amplifier module and a constant current output module; and the multi-channel peripheral nerve AC electric stimulation module is used for generating an AC electric stimulation signal. The electric stimulation device provided by the application can realize two modes of DC electric stimulation and AC electric stimulation at the same time, supports multi-channel independent control and flexible switching, and thus meets the requirements of different nerve regulation experiments and clinical applications.

Description

Technical Field

[0001] This application relates to the field of neurostimulation technology, and in particular to a multi-channel adjustable AC / DC neurostimulation device. Background Technology

[0002] Neuromuscular electrical stimulation (NMES) is a technique that uses external electrical signals to act on nerve or muscle tissue, thereby modulating nerve activity or inducing muscle contraction. By applying specific forms of electrical stimulation signals to the surface of nerve tissue or muscle, nerve fibers can be activated or the firing behavior of neurons can be modulated, causing depolarization or hyperpolarization responses in the nerve membrane. This induces nerve impulse transmission and triggers muscle contraction, thus achieving the regulation of nerve function. Compared with traditional drug therapy or passive rehabilitation methods, NMES has advantages such as strong controllability, good repeatability, and fewer side effects on the body. It has become an important technique in neurorehabilitation and neuromodulation research and has been widely used in fields such as neurorehabilitation, pain management, motor function recovery, and neuroscience research.

[0003] Currently, common neurostimulation devices mainly include transcutaneous electrical nerve stimulation (TENS) devices, functional electrical stimulation (FES) systems, and deep brain stimulation (DBS) devices. TENS devices primarily stimulate sensory nerves through transcutaneous electrodes to relieve pain; FES systems induce muscle contractions through electrical stimulation, thereby assisting patients in performing specific motor functions; and DBS systems stimulate deep brain nuclei through implanted electrodes to treat neurological diseases such as Parkinson's disease. These devices typically stimulate target nerve tissue by generating pulsed current or voltage signals, thereby modulating neural activity or inducing muscle contractions.

[0004] However, most existing neurostimulation devices have relatively simple stimulation mode designs, typically using pulse stimulation signals with fixed waveforms, such as a single square wave or pulsed AC signal, and only supporting limited parameter adjustments, such as stimulation frequency, pulse width, and current amplitude. Although these parameters can affect the stimulation effect to some extent, the limited type of stimulation waveform and modulation method often makes it difficult to achieve more flexible and precise neuromodulation when facing different experimental needs or individual patient differences.

[0005] Furthermore, with the deepening of research on neuromodulation, multichannel neurostimulation technology has gradually become a research hotspot. In practical applications, the human nervous system often involves the synergistic effects of multiple neural regions or muscle groups, thus requiring simultaneous or independent stimulation of different areas through multiple stimulation channels. However, existing neurostimulation devices still have certain limitations in terms of the number of channels and control methods. Some devices only support single-channel or limited-channel output, making it difficult to achieve simultaneous or independent stimulation of multiple neural regions; while some multichannel devices can achieve multi-point stimulation, they often lack completely independent parameter control capabilities between channels, making it difficult to set different stimulation modes and parameters for different neural regions, thus limiting their application in complex neuromodulation experiments and multi-regional neurostimulation.

[0006] Therefore, there is an urgent need to design a neural electrical stimulation device with a reasonable structure, diverse stimulation modes, the ability to achieve independent control of multiple channels, and the ability to flexibly adjust AC and DC stimulation signals, so as to improve the flexibility and applicability of neural electrical stimulation devices in neuromodulation research and clinical applications. Summary of the Invention

[0007] This application provides a multi-channel adjustable AC / DC nerve stimulation device that can simultaneously achieve both DC and AC stimulation modes, and supports independent control and flexible switching of multiple channels, thereby meeting the needs of different neuromodulation experiments and clinical applications.

[0008] To address the aforementioned technical problems, this application provides a multi-channel adjustable AC / DC nerve stimulation device. The device includes a main control module and a multi-channel peripheral nerve DC stimulation module and a multi-channel peripheral nerve AC stimulation module, both connected to the main control module. The multi-channel peripheral nerve DC stimulation module includes a switch matrix module, a constant current drive module, an H-bridge commutation module, and an overcurrent protection module. The multi-channel peripheral nerve DC stimulation module generates DC stimulation signals. It receives high voltage input from a power supply module and, in conjunction with the PWM of the main control module and the overcurrent protection module, constant current drive module, and H-bridge commutation module, generates the final DC waveform. The multi-channel peripheral nerve AC stimulation module includes a signal generation module, a filtering and coupling module, a power amplifier module, and a constant current output module. The multi-channel peripheral nerve AC stimulation module generates AC stimulation signals. It controls the signal generation module via the main control module to generate an AC waveform with adjustable frequency and amplitude, which then sequentially passes through the filtering and coupling module, the power amplifier module, and the constant current output circuit to output an AC stimulation current.

[0009] In some exemplary embodiments, the main control module receives control commands sent by the host computer and coordinates the multi-channel peripheral nerve DC stimulation module and the multi-channel peripheral nerve AC stimulation module to achieve stimulation mode selection, stimulation parameter adjustment and stimulation channel switching.

[0010] In some exemplary embodiments, the input terminal of the switch matrix module is connected to the output terminal of the H-bridge commutation module, and the output terminal of the switch matrix module is connected to the end to be tested. The switch matrix module is used to realize reconfigurable connections between multiple stimulation channels and multiple electrodes. By controlling the on and off of the switch unit, the stimulation signal can be flexibly switched between different electrodes, thereby realizing multi-region synchronous stimulation or independent stimulation.

[0011] In some exemplary embodiments, the power supply module outputs high voltage to the overcurrent protection module via a step-up / step-down module; the overcurrent protection module is used to limit the current rise or cut off the output when the output current exceeds a safety threshold, thereby improving system safety; the overcurrent protection module includes a bias resistor R1, a Zener diode D1, a transistor Q1, and a current-limiting resistor R2; the collector and base of the transistor Q1 are respectively connected to the two ends of the bias resistor R1, and the emitter of the transistor Q1 is connected to the positive terminal of the Zener diode D1 through the current-limiting resistor R2.

[0012] In some exemplary embodiments, the H-bridge commutation module uses an H-bridge topology to achieve periodic reversal of the current direction, outputting a bipolar positive and negative symmetrical stimulation waveform to ensure that the electrodes maintain charge balance during stimulation. The H-bridge commutation module includes four switching transistors: a first upper bridge arm switch Q1, a second upper bridge arm switch Q2, a first lower bridge arm switch Q3, and a second lower bridge arm switch Q4. The drains of Q1 and Q2 are connected to the output terminal of the overcurrent protection module, and the sources of Q3 and Q4 are connected to the input terminal of the constant current drive module. The source of Q1 and the drain of Q3 are connected to form a first output node, and the source of Q2 and the drain of Q4 are connected to form a second output node. The stimulation load is connected between the first output node and the second output node.

[0013] In some exemplary embodiments, the switching transistor is a field-effect transistor (MOSFET).

[0014] In some exemplary embodiments, the constant current drive module converts the control voltage generated by the digital-to-analog converter (DAC) into a stable constant current output through a voltage-controlled constant current source circuit, ensuring precise control of the stimulation current amplitude. The constant current drive module includes an operational amplifier OP1, a transistor Q1, and a sampling resistor R1. The non-inverting input of the operational amplifier OP1 is connected to the control voltage input VIN to receive the voltage control signal output from the main control module. Its inverting input is connected to one end of the sampling resistor R1 to detect the feedback voltage generated by the output current across R1. The other end of the sampling resistor R1 is grounded to convert the output current into a corresponding voltage signal, thereby forming a current negative feedback loop.

[0015] In some exemplary embodiments, the signal generation module uses a DDS chip to generate an AC stimulation signal; the DDS chip generates a high-precision digital sine wave signal through an internal phase accumulator and a lookup table (LUT), and outputs an analog signal through an internal digital-to-analog converter, thereby achieving precise control of the stimulation signal frequency; a decoupling capacitor C1 is provided at the DDS output terminal to suppress power supply noise and improve signal stability.

[0016] In some exemplary embodiments, the filtering and coupling module performs low-pass filtering and AC coupling at the DDS output to remove DC bias and suppress high-frequency noise, thereby obtaining a high-purity, low-distortion AC signal; the power amplifier module amplifies the signal amplitude based on the operational amplifier's power amplifier circuit to ensure that the output voltage meets the stimulation intensity requirements and maintains signal linearity and stability; the constant current output module adopts a Howland constant current source topology to convert the voltage signal into a stable constant current output, ensuring that the output current remains constant under different load conditions.

[0017] In some exemplary embodiments, the constant current output module adopts an improved HOWLAND constant current source structure, including operational amplifier OP1, operational amplifier OP2, resistors R1, R2, R3, R4, sampling resistor R0, and load RL; the input voltage UIN is connected to node U1 through resistor R3, and node U1 is also connected to the non-inverting input of operational amplifier OP1; the inverting input of operational amplifier OP1 is grounded through resistor R1 and connected to its output terminal U2 through resistor R2, thereby forming a feedback network; the output terminal U2 of operational amplifier OP1 is connected to the output node Uo through resistor R0, for supplying current to the load RL. L Provide output current i L Load R L The other end is grounded; node U1 is connected to the inverting input of operational amplifier OP2 through resistor R4. The output of operational amplifier OP2 is connected to the inverting input to form a unity-gain follower. Its non-inverting input is connected to the output node Uo to detect the output voltage and form a feedback signal.

[0018] The technical solution provided in this application has at least the following advantages: To address the shortcomings of existing nerve stimulation devices, such as limited stimulation modes, limited parameter adjustment capabilities, and insufficient independent multi-channel control, this application provides a multi-channel adjustable AC / DC nerve stimulation device. The device includes a main control module and a multi-channel peripheral nerve DC stimulation module and a multi-channel peripheral nerve AC stimulation module, both connected to the main control module. The multi-channel peripheral nerve DC stimulation module includes a switch matrix module, a constant current drive module, an H-bridge commutation module, and an overcurrent protection module. This module generates DC stimulation signals by receiving high voltage from a power supply module, which, in conjunction with the PWM of the main control module and the overcurrent protection module, constant current drive module, and H-bridge commutation module, generates the final DC waveform. The multi-channel peripheral nerve AC stimulation module includes a signal generation module, a filtering and coupling module, a power amplifier module, and a constant current output module. This module generates AC stimulation signals by controlling the signal generation module through the main control module to generate AC waveforms with adjustable frequency and amplitude, which then sequentially pass through the filtering and coupling module, power amplifier module, and constant current output circuit to output AC stimulation current.

[0019] First, this application integrates both direct current stimulation mode and alternating current stimulation mode, allowing for flexible selection of stimulation methods according to different experimental or therapeutic needs. This expands the application scope of the nerve stimulation device and improves its applicability in neuromodulation research and rehabilitation therapy.

[0020] Secondly, this application adopts a multi-channel structure design, in which the current amplitude, stimulation frequency, pulse width and phase of each stimulation channel can be adjusted independently. Combined with the switch matrix module, the reconfigurable connection between the stimulation channel and the electrode is realized, thereby enabling multi-point synchronous or asynchronous stimulation and multi-region nerve stimulation, improving the flexibility of stimulation position configuration and the application capability of the system.

[0021] Moreover, this application supports intermittent electrical stimulation, and the stimulation time and rest time can be flexibly set according to actual needs, making the electrical stimulation process more in line with the application characteristics of neuromodulation and rehabilitation training, while reducing the adverse effects of long-term continuous stimulation on biological tissues.

[0022] Finally, this application achieves real-time adjustment of stimulation mode, stimulation parameters, and stimulation time through the communication mechanism between the main control module and the host computer. Combined with the constant current drive circuit and high-voltage power supply design, the device can maintain a stable current output under high impedance load conditions, thereby improving the system's control flexibility, stability, and reliability. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0024] Figure 1 This is a schematic block diagram of the structure of a multi-channel adjustable AC / DC nerve stimulation device provided in an embodiment of this application.

[0025] Figure 2 This is a schematic diagram of the current waveform under two stimulation current output modes provided in an embodiment of this application.

[0026] Figure 3 This is a circuit diagram of an overcurrent protection module provided in one embodiment of this application.

[0027] Figure 4 This is a circuit diagram of an H-bridge commutation module provided in one embodiment of this application.

[0028] Figure 5 This is a circuit diagram of a constant current drive module provided in one embodiment of this application.

[0029] Figure 6 This is a circuit diagram of a signal generation, filtering coupling, and power amplifier module provided in an embodiment of this application.

[0030] Figure 7 This is a circuit diagram of a constant current output module provided in one embodiment of this application.

[0031] Figure 8 This is a bar chart showing the experimental results of the threshold values ​​of finger movements induced by peripheral nerve electrical stimulation (as a percentage of the maximum voluntary contractile force MVC) provided in one embodiment of this application. Detailed Implementation

[0032] As can be seen from the background technology, existing nerve electrical stimulation devices have problems such as a single stimulation mode, limited parameter adjustment capability, and insufficient multi-channel independent control capability.

[0033] To address the aforementioned technical problems, this application provides a multi-channel adjustable AC / DC nerve stimulation device. The device includes a main control module and a multi-channel peripheral nerve DC stimulation module and a multi-channel peripheral nerve AC stimulation module, both connected to the main control module. The multi-channel peripheral nerve DC stimulation module includes a switch matrix module, a constant current drive module, an H-bridge commutation module, and an overcurrent protection module. The multi-channel peripheral nerve DC stimulation module generates DC stimulation signals. It receives high voltage input from a power supply module and, in conjunction with the PWM of the main control module and the overcurrent protection module, constant current drive module, and H-bridge commutation module, generates the final DC waveform. The multi-channel peripheral nerve AC stimulation module includes a signal generation module, a filtering and coupling module, a power amplifier module, and a constant current output module. The multi-channel peripheral nerve AC stimulation module generates AC stimulation signals. It controls the signal generation module via the main control module to generate an AC waveform with adjustable frequency and amplitude, which then sequentially passes through the filtering and coupling module, the power amplifier module, and the constant current output circuit to output an AC stimulation current. This application provides a multi-channel adjustable AC / DC nerve stimulation device that can simultaneously achieve both DC and AC stimulation modes, and supports independent control and flexible switching of multiple channels, thereby meeting the needs of different neuromodulation experiments and clinical applications.

[0034] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0035] See Figure 1 This application provides a multi-channel adjustable AC / DC nerve stimulation device, comprising: a main control module and a multi-channel peripheral nerve DC stimulation module and a multi-channel peripheral nerve AC stimulation module respectively connected to the main control module; wherein, the multi-channel peripheral nerve DC stimulation module includes a switch matrix module, a constant current drive module, an H-bridge commutation module and an overcurrent protection module; the multi-channel peripheral nerve DC stimulation module is used to generate DC stimulation signals, and the module receives high voltage input through the power supply module, and generates the final DC waveform in conjunction with the PWM of the main control module and the overcurrent protection module, constant current drive module and H-bridge commutation module; the multi-channel peripheral nerve AC stimulation module includes a signal generation module, a filtering coupling module, a power amplifier module and a constant current output module; the multi-channel peripheral nerve AC stimulation module is used to generate AC stimulation signals, and the module controls the signal generation module through the main control module to generate AC waveforms with adjustable frequency and amplitude, and then outputs AC stimulation current through the filtering coupling module, power amplifier module and constant current output circuit in sequence.

[0036] In some embodiments, the main control module receives control commands sent by the host computer and coordinates the multi-channel peripheral nerve DC stimulation module and the multi-channel peripheral nerve AC stimulation module to achieve stimulation mode selection, stimulation parameter adjustment and stimulation channel switching.

[0037] In some embodiments, the input terminal of the switch matrix module is connected to the output terminal of the H-bridge commutation module, and the output terminal of the switch matrix module is connected to the end to be tested. The switch matrix module is used to realize reconfigurable connections between multiple stimulation channels and multiple electrodes. By controlling the on and off of the switch unit, the stimulation signal can be flexibly switched between different electrodes, thereby realizing multi-region synchronous stimulation or independent stimulation.

[0038] The switch matrix module consists of multiple sets of electronic switches or relays, which achieve reconfigurable connections between the stimulation output and different electrodes through a matrix connection structure. By controlling the on and off states of each switch unit, a pair of electrical stimulation signals can be switched to different stimulation positions, or multiple sets of electrical stimulation signals can be simultaneously output to different electrode positions, thereby achieving synchronous or independent stimulation of multiple regions.

[0039] The main control module (system control module) is used for unified control of the entire device. It includes a wireless transmission module and a serial communication module. The wireless transmission module enables wireless communication between the device and the host computer, while the serial communication module enables wired communication between the device and the host computer. After receiving control commands from the host computer, the system control module coordinates and controls the DC stimulation module, AC stimulation module, and switch matrix module to achieve functions such as stimulation mode selection, stimulation current parameter setting, stimulation time control, and channel switching.

[0040] The multi-channel adjustable AC / DC nerve stimulation device provided in this application includes both DC stimulation and AC stimulation modes. This device employs intermittent electrical stimulation, alternating between stimulation and rest phases. Users can flexibly set the stimulation and rest times according to experimental or therapeutic needs. The duration of both is not fixed and can be freely adjusted within a wide time range to meet the application requirements of different neuromodulation scenarios. Figure 2 This is a schematic diagram of the current waveform under the two stimulation current output modes according to this application.

[0041] In some embodiments, please continue reading Figure 1The power supply module outputs high voltage to the overcurrent protection module via a buck-boost module. The overcurrent protection module limits current rise or cuts off the output when the output current exceeds a safe threshold, thereby improving system safety. The power supply module provides a 12V input; the buck-boost module converts the 12V input voltage into multiple DC power supplies, including 3.3V, 5V, ±15V, and ±175V, to meet the operational requirements of various functional modules. The DC power supply can provide a maximum output current of 17mA, an output power of 3W, and an output current tolerance of less than 3%.

[0042] like Figure 3 As shown, the overcurrent protection module mainly consists of a bias resistor R1, a Zener diode D1, a transistor Q1, and a current-limiting resistor R2. The transistor is a high-voltage transistor to adapt to the high-voltage output operating environment of the nerve stimulation device.

[0043] The first end of the bias resistor R1 is connected to the current input terminal along with the collector of the transistor. The second end of the bias resistor R1 is connected to the cathode of the Zener diode and the base of the transistor Q1. The anode of the Zener diode D1 and the first end of the current limiting resistor R2 are connected to the current output terminal (or the next stage circuit node). The second end of the current limiting resistor R2 is connected to the emitter of the transistor Q1.

[0044] Under normal operating conditions, the detection voltage in the circuit is lower than the breakdown voltage of the Zener diode D1, so D1 is in the off state. The voltage between the base and emitter of Q1 is insufficient to turn it on, so Q1 remains off and has no effect on the main circuit. When the output current increases abnormally, the voltage at the corresponding node in the circuit rises, causing D1 to reach its breakdown voltage and turn on. This establishes a bias voltage between the base and emitter of Q1, turning it on. After Q1 turns on, it modulates the relevant drive signal or current path, thereby limiting the output current from continuing to rise or triggering the protection mechanism, thus achieving overcurrent protection for the circuit.

[0045] like Figure 4 As shown, the H-bridge commutation module mainly consists of four switching transistors: Q1 (first upper bridge arm), Q2 (second upper bridge arm), Q3 (first lower bridge arm), and Q4 (second lower bridge arm). These transistors are preferably field-effect transistors (MOSFETs). The drains of Q1 and Q2 are connected to the output terminal of the overcurrent protection circuit, and the sources of Q3 and Q4 are connected to the input terminal of the constant current drive module. The source of Q1 and the drain of Q3 are connected to form the first output node, and the source of Q2 and the drain of Q4 are connected to form the second output node. The stimulating load is connected between the first and second output nodes.

[0046] It should be noted that the positive and negative electrodes of the electrical stimulation channel are attached to the skin surface of the subject, and the resistance of the human skin constitutes the stimulation load.

[0047] The gates of the four switching transistors are connected to the PWM1, PWM2, PWM3, and PWM4 signal terminals output by the system control module, respectively. In the forward stimulation state, the control module turns on Q1 and Q4 and turns off Q2 and Q3. The current flows from the output terminal of the overcurrent protection through Q1, the stimulation load, and Q4 to the input terminal of the constant current drive module, thereby forming a forward stimulation current. In the reverse stimulation state, Q2 and Q3 are turned on and Q1 and Q4 are turned off, thereby forming a reverse stimulation current and realizing the periodic reversal of the direction of the stimulation current.

[0048] like Figure 5 As shown, this constant current drive module mainly consists of an operational amplifier OP1, a transistor Q1, and a sampling resistor R1. The non-inverting input of the operational amplifier OP1 is connected to the control voltage input VIN to receive the voltage control signal from the system control module or the digital-to-analog converter (DAC); its inverting input is connected to the upper end of the sampling resistor R1 to detect the feedback voltage generated across R1 by the output current. The lower end of the sampling resistor R1 is grounded to convert the output current into a corresponding voltage signal, thereby forming a current negative feedback loop.

[0049] Transistor Q1 is an NPN transistor. Its base is connected to the output of operational amplifier OP1, its collector is connected to node U, which is connected to the source of switching transistors Q3 and Q4 in the H-bridge commutation module, and its emitter is connected to the upper end of sampling resistor R1.

[0050] During operation, operational amplifier OP1 uses negative feedback control to keep the voltage at its inverting input equal to VIN, thereby adjusting the conduction level of transistor Q1 and stabilizing the voltage across sampling resistor R1 at the set value of VIN. According to Ohm's law, the output current satisfies: .

[0051] The output stimulation current can be precisely adjusted by regulating the control voltage VIN, and a stable constant current output can be maintained even when the load impedance changes.

[0052] The multi-channel peripheral nerve AC stimulation module includes a signal generation (DDS) module, a filtering and coupling module, a power amplifier module, and a constant current output module.

[0053] like Figure 6 As shown, the signal generation, filtering, coupling, and power amplification module is used to generate a stable AC stimulus signal and to filter, shape, and amplify the signal to meet the driving requirements of the subsequent constant current output module. This module mainly includes a direct digital synthesis (DDS) signal generation unit, a filtering and coupling unit, and a power amplification unit.

[0054] The signal generation unit uses a DDS chip to generate AC stimulation signals. The DDS chip generates a high-precision digital sine wave signal through an internal phase accumulator and lookup table (LUT), and outputs an analog signal via an internal digital-to-analog converter, thereby achieving precise control of the stimulation signal frequency. A decoupling capacitor C1 is provided at the DDS output terminal to suppress power supply noise and improve signal stability.

[0055] The filtering and coupling unit is connected after the DDS output terminal and is used to perform low-pass filtering and AC coupling processing on the DDS output signal. This unit mainly consists of coupling capacitor C2 and filter resistor R1. It uses an RC network to suppress high-frequency noise and digital quantization noise in the signal, while isolating the DC component in the signal, so that the output signal maintains good AC characteristics, thereby improving the purity and stability of the stimulus signal.

[0056] The power amplifier unit employs an operational amplifier to form a voltage follower and non-inverting amplification circuit. The input of operational amplifier OP1 is connected to the output of the filtering and coupling unit for buffering and amplifying the AC signal. The output of operational amplifier OP1 is connected to the subsequent circuit via a coupling capacitor and resistor network to provide sufficient drive capability and maintain the linearity of the signal. This power amplifier circuit can increase the output voltage amplitude while maintaining signal waveform stability, thereby meeting the requirements of the nerve electrical stimulation device for AC stimulation signal amplitude and drive capability.

[0057] like Figure 7 As shown, the constant current output module adopts an improved HOWLAND constant current source structure, mainly composed of operational amplifiers OP1 and OP2, resistors R1, R2, R3, and R4, sampling resistor R0, and load RL. The input voltage UIN is connected to node U1 through resistor R3, which is also connected to the non-inverting input of operational amplifier OP1. The inverting input of operational amplifier OP1 is grounded through resistor R1 and connected to its output U2 through resistor R2, thus forming a feedback network.

[0058] The output terminal U2 of operational amplifier OP1 is connected to the output node Uo via resistor R0 to provide the output current iL to the load RL. The other end of the load is grounded. Node U1 is connected to the inverting input terminal of operational amplifier OP2 via resistor R4. The output terminal of operational amplifier OP2 and its inverting input terminal are connected to form a unity-gain follower. Its non-inverting input terminal is connected to the output node Uo to detect the output voltage and generate a feedback signal. During operation, the input voltage UIN acts as a control signal on node U1. Operational amplifier OP1 adjusts the output voltage U2 through the feedback network, while operational amplifier OP2 detects the voltage at output node Uo and forms an overall negative feedback loop through resistor R4, thereby stabilizing the voltage drop across the sampling resistor R0 and keeping the current flowing through the load RL constant. When the resistor parameters satisfy a proportional relationship... At this time, the circuit can achieve high-precision constant current output, and its output current is approximately... .

[0059] Therefore, by adjusting the amplitude of the input voltage UIN, precise control of the output current can be achieved, and the impact of load impedance changes on the output current can be reduced within a certain range, thereby ensuring the stability of the stimulation current.

[0060] The multi-channel adjustable AC / DC nerve stimulation device supports both DC and AC stimulation modes. It employs an intermittent stimulation strategy, alternating between stimulation and rest phases. Users can set the stimulation and rest times via the system control module according to experimental research or treatment needs; both durations are adjustable within a wide range to suit various neuromodulation or rehabilitation applications.

[0061] In DC stimulation mode, the device outputs a bipolar symmetrical pulsed current signal with an output current range of 0 to ±17 mA and an output voltage range of 0 to ±170 V, with a current adjustment step of 0.01 mA; the stimulation pulse width ranges from 100 μs to 1000 μs, with a pulse width adjustment step of 1 μs; and the stimulation frequency ranges from 0 to 1000 Hz, with a frequency adjustment step of 0.1 Hz. By adjusting these parameters, precise stimulation control of different nerve or muscle tissues can be achieved.

[0062] In AC stimulation mode, the device outputs a bipolar symmetrical sinusoidal current signal with an output current amplitude range of 0 to ±17 mA and an output voltage range of 0 to ±170 V. The current amplitude adjustment step is 0.05 mA. The stimulation signal frequency range is 0–30 kHz with a frequency adjustment step of 0.01 Hz. Simultaneously, the phase of each channel stimulation signal can be adjusted within the range of 0 to 2π with a phase adjustment step of 0.01 rad, thereby achieving phase control between multi-channel stimulation signals to meet the needs of multi-region neural modulation experiments.

[0063] The switch matrix module enables flexible connections between multiple stimulation channels and multiple electrodes. This module consists of multiple sets of electronic switches or relays, which, through a matrix connection structure, achieve reconfigurable connections between the stimulation output and different electrodes. Compared to most existing electrical stimulation devices that only have fixed connection positions for the stimulation electrodes, this device, through the switch matrix module, can flexibly switch a pair of electrical stimulation signals to different stimulation positions by controlling the on and off states of the switch units, or simultaneously output two or more sets of electrical stimulation signals to different electrode positions, thereby achieving synchronous or independent stimulation of multiple regions. With this structure, users can change the stimulation area without replacing or reconnecting electrodes, improving the system's flexibility and applicability in multi-site neural stimulation experiments, and supporting the needs of multi-channel synergistic stimulation and complex neural modulation experiments.

[0064] The system control module uses a microcontroller as its core control unit and includes a wireless transmission module and a serial communication module. The wireless transmission module, which can use Bluetooth communication, enables wireless data transmission between the device and the host computer; the serial communication module provides a wired communication connection between the device and the host computer. Users can send control commands through the host computer interface and transmit them to the system control module via the wireless transmission module or the serial communication module. After receiving and parsing the control commands, the system control module coordinates the control of the DC stimulation module, AC stimulation module, and switch matrix module, thereby enabling functions such as stimulation mode selection, stimulation current parameter setting, stimulation time control, and channel switching. Through these control methods, users can adjust the device's output mode, current amplitude, stimulation frequency, and stimulation time in real time on the host computer interface, achieving flexible control and remote management of the nerve electrical stimulation process.

[0065] Each stimulation channel of the multi-channel adjustable AC / DC neural electrical stimulation device supports independent parameter control. The system control module can set parameters such as stimulation current amplitude, stimulation frequency, stimulation pulse width, stimulation phase, and stimulation time for each stimulation channel, and independently control the start and stop of different channels according to user commands. Through this structure, each channel can achieve parallel output of different stimulation parameters in the same device, thereby supporting differentiated or synergistic stimulation of multiple neural regions. Furthermore, in AC stimulation mode, the phase and frequency of the output signal of each channel can also be independently adjusted to achieve phase control and synchronous modulation between multi-channel stimulation signals, meeting the needs of complex neural modulation experiments for multi-channel stimulation strategies.

[0066] The power supply module in the multi-channel adjustable AC / DC nerve stimulation device provides a 12V power input. The buck-boost module converts the 12V input voltage into multiple DC power supplies, including 3.3V, 5V, ±15V, and ±175V, to meet the operational requirements of each functional module. Among them, the high-voltage DC power supply is used to drive the H-bridge commutation circuit and constant current drive unit of the stimulation module, and can output a maximum current of 17mA with a power output of 3W. The output current fault rate is less than 3%, ensuring stable constant current output even under high impedance load conditions. The low-voltage and medium-voltage DC power supplies are used for the control module, signal processing module, and amplification circuit, ensuring the accurate and stable operation of each electronic component and providing the necessary power support for the constant current output of the AC stimulation module.

[0067] To further verify the practical application effect and technical feasibility of the multi-channel adjustable AC / DC nerve electrical stimulation device described in this application, this embodiment provides a method for verifying and testing electrical stimulation for peripheral motor nerve modulation. The specific verification process and results are as follows: (1) Preparation for baseline measurement: Before electrical stimulation, the maximum voluntary contraction (MVC) of each finger of the subject under maximum force was measured and recorded using a high-precision mechanical sensor. This value will serve as the baseline reference value for subsequent evaluation of the intensity of muscle contraction induced by electrical stimulation.

[0068] (2) Electrode configuration and channel mapping: Using the unique switch matrix module of this device, the electrodes of the stimulation output channel are flexibly configured and attached to the body surface near the peripheral nerve bundle of the subject's upper arm.

[0069] (3) Parameter adjustment and stimulation application: Stimulation parameters are set through the system control module (host computer). DC pulses are selected, and the amplitude, frequency and pulse width of the stimulation current of each channel are gradually fine-tuned within a safe range to apply electrical stimulation of a specific intensity to the peripheral nerve bundle of the upper arm, thereby inducing depolarization of the target nerve fiber.

[0070] (4) Data Acquisition and Verification Results: During the application of electrical stimulation, significant flexion movements were successfully induced in each finger of the subject. The magnitude of the flexion force of each finger was simultaneously measured in real time using a mechanical sensor. For example... Figure 8 As shown in the figure, experiments have demonstrated that, under the stimulation of the device described in this application, the average flexion force of each finger of the subject exceeded 50% MVC.

[0071] The verification results fully demonstrate that the multi-channel adjustable AC / DC nerve stimulation device of this application can accurately and safely activate peripheral motor nerves, induce high-intensity target muscle contraction, and has excellent neuromuscular control capabilities, meeting the practical application needs of clinical neurorehabilitation and complex neuroscience research.

[0072] Based on the above technical solutions, this application provides a multi-channel adjustable AC / DC nerve stimulation device. The device includes a main control module and a multi-channel peripheral nerve DC stimulation module and a multi-channel peripheral nerve AC stimulation module, both connected to the main control module. The multi-channel peripheral nerve DC stimulation module includes a switch matrix module, a constant current drive module, an H-bridge commutation module, and an overcurrent protection module. The multi-channel peripheral nerve DC stimulation module generates DC stimulation signals. This module receives high voltage input from the power supply module and, in conjunction with the PWM of the main control module and the overcurrent protection module, constant current drive module, and H-bridge commutation module, generates the final DC waveform. The multi-channel peripheral nerve AC stimulation module includes a signal generation module, a filtering and coupling module, a power amplifier module, and a constant current output module. The multi-channel peripheral nerve AC stimulation module generates AC stimulation signals. This module controls the signal generation module through the main control module to generate an AC waveform with adjustable frequency and amplitude, which then sequentially passes through the filtering and coupling module, the power amplifier module, and the constant current output circuit to output the AC stimulation current.

[0073] First, this application integrates both direct current stimulation mode and alternating current stimulation mode, allowing for flexible selection of stimulation methods according to different experimental or therapeutic needs. This expands the application scope of the nerve stimulation device and improves its applicability in neuromodulation research and rehabilitation therapy.

[0074] Secondly, this application adopts a multi-channel structure design, in which the current amplitude, stimulation frequency, pulse width and phase of each stimulation channel can be adjusted independently. Combined with the switch matrix module, the reconfigurable connection between the stimulation channel and the electrode is realized, thereby enabling multi-point synchronous or asynchronous stimulation and multi-region nerve stimulation, improving the flexibility of stimulation position configuration and the application capability of the system.

[0075] Moreover, this application supports intermittent electrical stimulation, and the stimulation time and rest time can be flexibly set according to actual needs, making the electrical stimulation process more in line with the application characteristics of neuromodulation and rehabilitation training, while reducing the adverse effects of long-term continuous stimulation on biological tissues.

[0076] Finally, this application achieves real-time adjustment of stimulation mode, stimulation parameters, and stimulation time through the communication mechanism between the main control module and the host computer. Combined with the constant current drive circuit and high-voltage power supply design, the device can maintain a stable current output under high impedance load conditions, thereby improving the system's control flexibility, stability, and reliability.

[0077] Those skilled in the art will understand that the above-described embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A multi-channel adjustable AC / DC nerve electrical stimulation device, characterized in that, The device includes: a main control module, and a multi-channel peripheral nerve direct current stimulation module and a multi-channel peripheral nerve alternating current stimulation module, both connected to the main control module; wherein... The multi-channel peripheral nerve DC stimulation module includes a switch matrix module, a constant current drive module, an H-bridge commutation module, and an overcurrent protection module. The multi-channel peripheral nerve DC stimulation module is used to generate DC stimulation signals. The module receives high voltage input through the power supply module and, in conjunction with the PWM of the main control module and the overcurrent protection module, constant current drive module, and H-bridge commutation module, generates the final DC waveform. The multi-channel peripheral nerve AC stimulation module includes a signal generation module, a filtering and coupling module, a power amplifier module, and a constant current output module. The multi-channel peripheral nerve AC stimulation module is used to generate AC stimulation signals. The module controls the signal generation module through the main control module to generate AC waveforms with adjustable frequency and amplitude, and then outputs AC stimulation current through the filtering and coupling module, the power amplifier module, and the constant current output circuit in sequence.

2. The multi-channel adjustable AC / DC nerve stimulation device according to claim 1, characterized in that, The main control module receives control commands sent by the host computer and coordinates the multi-channel peripheral nerve DC stimulation module and the multi-channel peripheral nerve AC stimulation module to achieve stimulation mode selection, stimulation parameter adjustment and stimulation channel switching.

3. The multi-channel adjustable AC / DC nerve stimulation device according to claim 1, characterized in that, The input terminal of the switch matrix module is connected to the output terminal of the H-bridge commutation module, and the output terminal of the switch matrix module is connected to the terminal under test. The switch matrix module is used to realize reconfigurable connections between multiple stimulation channels and multiple electrodes. By controlling the on and off of the switch unit, the stimulation signal can be flexibly switched between different electrodes, thereby realizing synchronous stimulation or independent stimulation of multiple regions.

4. The multi-channel adjustable AC / DC nerve stimulation device according to claim 1, characterized in that, The power supply module outputs high voltage to the overcurrent protection module through a step-up / step-down module; the overcurrent protection module is used to limit the current rise or cut off the output when the output current exceeds the safety threshold, thereby improving system safety. The overcurrent protection module includes a bias resistor R1, a Zener diode D1, a transistor Q1, and a current-limiting resistor R2. The collector and base of the transistor Q1 are connected to the two ends of the bias resistor R1, and the emitter of the transistor Q1 is connected to the positive terminal of the Zener diode D1 through the current-limiting resistor R2.

5. The multi-channel adjustable AC / DC nerve stimulation device according to claim 1, characterized in that, The H-bridge commutation module uses an H-bridge topology to achieve periodic reversal of the current direction and outputs a bipolar positive and negative symmetrical stimulation waveform to ensure that the electrodes maintain charge balance during stimulation. The H-bridge commutation module includes four switches: a first upper bridge arm switch Q1, a second upper bridge arm switch Q2, a first lower bridge arm switch Q3, and a second lower bridge arm switch Q4. The drains of Q1 and Q2 are connected to the output of the overcurrent protection module, and the sources of Q3 and Q4 are connected to the input of the constant current drive module. The source of Q1 and the drain of Q3 are connected to form a first output node, and the source of Q2 and the drain of Q4 are connected to form a second output node. The stimulating load is connected between the first output node and the second output node.

6. The multi-channel adjustable AC / DC nerve stimulation device according to claim 5, characterized in that, The switching transistor is a field-effect transistor.

7. The multi-channel adjustable AC / DC nerve stimulation device according to claim 1, characterized in that, The constant current drive module converts the control voltage generated by the digital-to-analog converter (DAC) into a stable constant current output through a voltage-controlled constant current source circuit, ensuring precise control of the stimulation current amplitude. The constant current drive module includes an operational amplifier OP1, a transistor Q1, and a sampling resistor R1; The non-inverting input of operational amplifier OP1 is connected to the control voltage input VIN to receive the voltage control signal output from the main control module. Its inverting input is connected to one end of the sampling resistor R1 to detect the feedback voltage generated by the output current on R1; the other end of the sampling resistor R1 is grounded to convert the output current into a corresponding voltage signal, thereby forming a current negative feedback loop.

8. The multi-channel adjustable AC / DC nerve stimulation device according to claim 1, characterized in that, The signal generation module uses a DDS chip to generate an AC stimulation signal. The DDS chip generates a high-precision digital sine wave signal through an internal phase accumulator and a lookup table (LUT), and outputs an analog signal through an internal digital-to-analog converter, thereby achieving precise control of the stimulation signal frequency. A decoupling capacitor C1 is set at the DDS output terminal to suppress power supply noise and improve signal stability.

9. The multi-channel adjustable AC / DC nerve stimulation device according to claim 8, characterized in that, The filtering and coupling module performs low-pass filtering and AC coupling at the DDS output to remove DC bias and suppress high-frequency noise, thereby obtaining a high-purity, low-distortion AC signal. The power amplifier module amplifies the signal amplitude based on the power amplifier circuit of the operational amplifier, ensuring that the output voltage meets the stimulation intensity requirements and maintains the linearity and stability of the signal. The constant current output module adopts the Howland constant current source topology to convert the voltage signal into a stable constant current output, ensuring that the output current remains constant under different load conditions.

10. The multi-channel adjustable AC / DC nerve electrical stimulation device according to claim 1, characterized in that, The constant current output module adopts an improved HOWLAND constant current source structure, including operational amplifier OP1, operational amplifier OP2, resistors R1, R2, R3, R4, sampling resistor R0, and load RL; The input voltage UIN is connected to node U1 through resistor R3. Node U1 is also connected to the non-inverting input of operational amplifier OP1. The inverting input of operational amplifier OP1 is grounded through resistor R1 and connected to its output U2 through resistor R2, thus forming a feedback network. The output terminal U2 of operational amplifier OP1 is connected to the output node Uo via resistor R0, for supplying power to the load R. L Provide output current i L Load R L The other end is grounded; node U1 is connected to the inverting input of operational amplifier OP2 through resistor R4. The output of operational amplifier OP2 is connected to the inverting input to form a unity-gain follower. Its non-inverting input is connected to the output node Uo to detect the output voltage and form a feedback signal.

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