Neuromodulation system and method for ventral epidural region of spinal cord

Abstract

The present application provides a nerve regulation system and method for the ventral epidural region of the spinal cord, wherein the nerve regulation system for the ventral epidural region of the spinal cord generates a multi-channel pulse width modulation signal by using a microprocessor, drives a voltage-controlled current source after amplitude adjustment, and outputs a stimulation current with adjustable frequency, pulse width and amplitude to act on the ventral nerve structure of the spinal cord. Real-time monitoring of the stimulation current of each channel is realized by combining voltage sampling and single-pole multi-throw analog switches, while the feedback information of multiple modal sensors such as body position, electromyography and pressure is integrated to construct a closed-loop control mechanism, realize dynamic adjustment and individual optimization of the electric stimulation parameters. The precise activation ability of motor and autonomic nerve function is enhanced, and the present application has the advantages of more accurate electric stimulation positioning, more sensitive reaction, more intelligent control and the like, and is suitable for intelligent rehabilitation intervention in scenes such as spinal cord injury, cerebral palsy, and nerve dysfunction.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a neuromodulation system and method for the ventral epidural region of the spinal cord. Background Technology

[0002] Spinal cord injury (SCI) refers to damage to the spinal cord caused by trauma or non-traumatic factors. SCI disrupts communication between the spinal cord centers and spinal circuits, leading to a range of motor dysfunctions. Following injury, the local microenvironment of the spinal cord is unfavorable for nerve regeneration, further limiting the natural recovery of nerve function.

[0003] Epidural electrical stimulation (EES), as an emerging fully implantable neuromodulation technology, typically consists of two parts: electrodes and a pulse transmitter, with the pulse transmitter being the core component of the entire system. Its main function is to generate electrical pulse signals based on spatiotemporal sequence differential programming, specifically activating motor neuron nuclei according to physiological needs, thereby controlling the continuous, natural contraction and movement of paralyzed muscles and joints. This achieves continuous and coordinated control of paralyzed muscles and joints, restoring complex motor functions such as standing, walking, cycling, and swimming.

[0004] Currently, most mainstream EES systems employ a dorsal epidural approach, implanting electrodes into the dorsal region of the spinal cord. A large number of clinical applications and commercial products primarily revolve around this approach, optimizing pulse parameters and dorsal localization strategies to enhance electric field coverage and neural activation. However, with a deeper understanding of spinal cord neural networks, increasing research evidence suggests that the ventral spinal cord region, particularly its motor-related neurons and autonomic neurons, possesses superior electrophysiological response mechanisms and neural modulatory advantages in areas such as motor function recovery and urinary regulation.

[0005] Currently, there is a lack of EES neuromodulation systems designed specifically for the ventral spinal cord region, particularly in terms of pulse parameter settings, where there is no systematic optimization specifically for the ventral neural structures. Furthermore, existing EES neuromodulation systems are mostly semi-automatic controls with limited closed-loop capabilities, lacking comprehensive integration of external information such as body position perception, motor intention, and electromyographic signals. This makes it difficult to achieve real-time perception of the patient's motor state and adaptive adjustment of stimulation parameters, and to adjust stimulation parameters adaptively according to the patient's movement status. This technological gap severely restricts the application of EES in dynamic motion control and refined neuromodulation, becoming a key bottleneck in motor function reconstruction scenarios such as SCI and cerebral palsy. Summary of the Invention

[0006] In view of this, the present invention provides a neuromodulation system for the ventral epidural region of the spinal cord. One or more embodiments of this specification also relate to a neuromodulation method for the ventral epidural region of the spinal cord, to address the technical deficiencies existing in the prior art.

[0007] According to a first aspect of the present invention, a neuromodulation system for the ventral epidural region of the spinal cord is provided, comprising:

[0008] Embedded processor;

[0009] An electrical stimulation current generation module, connected to an embedded processor, is used to generate N independent pulse currents according to the control signal of the embedded processor, where N is an integer greater than or equal to 1;

[0010] An electrode array, comprising N electrode plates, is connected to the output of an electrical stimulation current generation module to apply pulsed current to the human body.

[0011] A real-time current monitoring module, connected to the electrode array and the embedded processor, is used to monitor the amplitude of the pulse current flowing through each electrode in real time and generate a first feedback signal to the embedded processor.

[0012] An electrical stimulation effect detection module, connected to an embedded processor, is used to detect the body's response signals under electrical stimulation and generate a second feedback signal to the embedded processor.

[0013] The human-computer interaction module, connected to the embedded processor, is used to display system status information and interact with the user.

[0014] The embedded processor is configured to adjust the control signal output to the electrical stimulation current generation module in real time based on the first feedback signal and the second feedback signal to form a closed-loop control system, thereby dynamically adjusting the parameters of the pulse current.

[0015] In some implementations, the electrical stimulation current generating module includes:

[0016] N amplitude regulators, whose input terminals receive N fixed-amplitude PWM signals generated by the embedded processor, and whose control terminals receive control signals from the embedded processor, are used to output N PFWHMn voltage signals with adjustable frequency, pulse width and amplitude.

[0017] N voltage-controlled current sources have their input terminals connected to the output terminals of N amplitude regulators, respectively, to convert the PFWHMn voltage signal into corresponding pulse currents, and the amplitude of the pulse currents is not affected by the downstream load.

[0018] In some implementations, the amplitude modulator includes a digital potentiometer and a first operational amplifier;

[0019] The digital potentiometer receives a PWM signal and a ground signal at its two ends, respectively. Its taps are controlled by a control signal and are used to divide the PWM signal.

[0020] The first operational amplifier forms a voltage follower, with its input connected to the tap of a digital potentiometer and its output outputting the PFWHMn voltage signal.

[0021] In some implementations, the voltage-controlled current source includes a sampling resistor, an operational amplifier, and a high-precision instrumentation amplifier, wherein,

[0022] A gain resistor R is connected between the two input terminals of the instrumentation amplifier. G ;

[0023] The output of the instrumentation amplifier is output to the corresponding electrode plate through the sampling resistor. Its non-inverting input receives the PFWHMn voltage signal, and its inverting input is grounded.

[0024] The operational amplifier's output and inverting input are both connected to the reference voltage terminal of the instrumentation amplifier, and its non-inverting input is connected to the corresponding electrode plate. The operational amplifier constitutes a voltage follower.

[0025] The stimulation current In applied to the electrode pads and the voltage signal PFWHMn output by the amplitude modulator satisfy the following relationship:

[0026]

[0027] Among them, A G R is the voltage gain of the instrumentation amplifier. AD It is the resistance value of the internal resistor of the chip, R. G Rs is the resistance value of the gain resistor, and Rs is the resistance value of the sampling resistor.

[0028] In some embodiments, the voltage-controlled current source includes a first operational amplifier, a second operational amplifier, a transistor, a first resistor, a second resistor, and a sampling resistor, wherein,

[0029] The output of the first operational amplifier is connected to the base of the transistor, its non-inverting input receives the PFWHMn voltage signal, and its inverting input is connected to the output of the second operational amplifier.

[0030] The non-inverting input of the second operational amplifier is connected to the emitter of the transistor, and its inverting input is connected to the inverting input of the first operational amplifier via a first resistor, and grounded via a second resistor.

[0031] The first operational amplifier and the second operational amplifier constitute a deep negative feedback circuit;

[0032] The collector of a transistor is connected to the corresponding electrode plate, and its emitter is grounded through a sampling resistor.

[0033] The stimulation current In applied to the electrode pads and the voltage signal PFWHMn output by the amplitude modulator satisfy the following relationship:

[0034]

[0035] Where R1 and R2 are the resistance values ​​of the first resistor and the second resistor, respectively, and Rs is the resistance value of the sampling resistor.

[0036] In some implementations, the real-time current monitoring module includes:

[0037] N voltage sampling and follower units, each unit is used to acquire the voltage across the sampling resistor in the corresponding electrode circuit and output a voltage pulse signal proportional to the pulse current;

[0038] A single-pole multi-throw analog switch has multiple input terminals connected to the output terminals of N voltage sampling and follower units, and its control terminal is controlled by an embedded processor to sequentially select voltage pulse signals.

[0039] A low-pass filter, connected to the output of a single-pole multi-throw analog switch, is used to extract the DC component of the selected voltage pulse signal.

[0040] The embedded processor is connected to the output of the low-pass filter and is configured to calculate the amplitude of the pulse current based on the DC component and the known frequency and pulse width of the corresponding pulse current.

[0041] In some embodiments, the low-pass filter includes a first capacitor, a second capacitor, a sixth operational amplifier, a fourth resistor, a fifth resistor, and a sixth resistor, wherein,

[0042] The first terminal of the first capacitor and the first terminal of the second capacitor are respectively connected to the two ends of the fourth resistor, and the second terminals of the first capacitor and the second terminals of the second capacitor are grounded.

[0043] The first end of the fourth resistor is connected to the output of the single-pole multi-throw analog switch, and its second end is connected to the non-inverting input of the sixth operational amplifier.

[0044] The inverting input of the sixth operational amplifier is grounded on one hand through the fifth resistor and connected to its output on the other hand through the sixth resistor. Its output is connected to the ADC in the embedded processor.

[0045] In some implementations, the electrical stimulation effect detection module includes:

[0046] At least one vital sign sensor is used to detect the physical response of the human body to electrical stimulation;

[0047] The signal conditioning circuit, connected to the vital signs sensor, is used to condition the signal output by the vital signs sensor to the sampling range of the analog-to-digital converter of the embedded processor.

[0048] A single-pole multi-throw analog switch has multiple input terminals connected to the output terminals of one or more signal conditioning circuits. Its control terminal is controlled by an embedded processor to sequentially select conditioned vital signs.

[0049] In some implementations, the embedded processor is specifically used for:

[0050] The system receives user-defined target stimulus parameters and / or safety thresholds through the human-computer interaction module.

[0051] The current amplitude fed back by the real-time current monitoring module is compared with the safety threshold. If it exceeds the range, an alarm is triggered or the output is automatically cut off.

[0052] The body's response signal fed back by the electrical stimulation effect detection module is compared with the expected effect, and at least one parameter among the frequency, pulse width and amplitude of the pulse current is automatically adjusted based on the preset control algorithm so that the body's response signal approaches the expected effect.

[0053] According to a second aspect of the present invention, a method for neuromodulation of the ventral epidural region of the spinal cord is provided, the method being applied to the aforementioned neuromodulation system for the ventral epidural region of the spinal cord, the method comprising:

[0054] The user interacts with the computer through the human-computer interaction module to perform operations and set parameters.

[0055] N independent pulse currents are generated and applied to the ventral epidural region of the spinal cord through an electrode array;

[0056] The amplitude of the N-channel pulse current is monitored in real time to generate the first feedback signal;

[0057] It detects the body's response to electrical stimulation and generates a second feedback signal;

[0058] Based on the first and second feedback signals, the control parameters used to generate pulse current are adjusted in real time to form a closed-loop control to dynamically optimize the effect of electrical stimulation.

[0059] The first feedback signal, the second feedback signal, and the system status are displayed in real time through the human-computer interaction module.

[0060] At least one embodiment of this invention employs a microprocessor to generate multiple pulse width modulation signals, which, after amplitude adjustment, drive a voltage-controlled current source to output a stimulation current with adjustable frequency, pulse width, and amplitude, acting on the ventral spinal cord neural structures. Real-time monitoring of the stimulation current in each channel is achieved through a combination of voltage sampling and a single-pole multi-throw analog switch. Simultaneously, feedback information from multimodal sensors such as body position, electromyography, and pressure is integrated to construct a closed-loop control mechanism, enabling dynamic adjustment and individualized optimization of electrical stimulation parameters. Compared to existing dorsal electrical stimulation neuromodulation schemes, this invention establishes a parameter-targeted regulation system for the ventral spinal cord region for the first time, enhancing the precise activation capability of motor and autonomic nerve functions. It has advantages such as more accurate electrical stimulation positioning, more sensitive response, and more intelligent control, making it suitable for intelligent rehabilitation intervention in scenarios such as spinal cord injury, cerebral palsy, and neurological dysfunction. Attached Figure Description

[0061] Figure 1 This is a diagram illustrating the overall architecture of a neuromodulation system for the ventral epidural region of the spinal cord, as provided by this invention.

[0062] Figure 2 This invention provides an amplitude modulator principle circuit for a neuromodulation system for the ventral epidural region of the spinal cord.

[0063] Figure 3 This invention provides a voltage-controlled current source circuit consisting of an instrumentation amplifier for a neuromodulation system for the ventral epidural region of the spinal cord.

[0064] Figure 4 This invention provides a voltage-controlled current source circuit based on an operational amplifier and a transistor, which is used in a neuromodulation system for the ventral epidural region of the spinal cord.

[0065] Figure 5 This invention provides a voltage sampling and follower principle circuit for a neuromodulation system for the ventral epidural region of the spinal cord;

[0066] Figure 6 This invention provides a 1×K single-pole multi-throw analog switch principle circuit composed of multiple analog switch chips for a neuromodulation system for the ventral epidural region of the spinal cord.

[0067] Figure 7 This invention provides a low-pass filter principle circuit for a neuromodulation system for the ventral epidural region of the spinal cord.

[0068] Figure 8 This is a flowchart of a neuromodulation method for the ventral epidural region of the spinal cord provided by the present invention. Detailed Implementation

[0069] Many specific details are set forth in the following description to provide a full understanding of this specification. However, this specification can be implemented in many other ways than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this specification. Therefore, this specification is not limited to the specific implementations disclosed below.

[0070] The terminology used in one or more embodiments of this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the one or more embodiments of this specification. The singular forms “a” and “the” as used in one or more embodiments of this specification and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in one or more embodiments of this specification refers to and includes any or all possible combinations of one or more associated listed items. The modifications “a” and “a plurality” as used in this disclosure are illustrative and not restrictive, and those skilled in the art will understand that they should be understood as “one or more” unless the context clearly indicates otherwise.

[0071] It should be understood that although the terms first, second, etc., may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first may also be referred to as second without departing from the scope of one or more embodiments of this specification, and similarly, second may also be referred to as first. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0072] See Figure 1 , Figure 1 A simplified structural diagram of a neuromodulation system for the ventral epidural region of the spinal cord, according to some embodiments of this specification, is shown, specifically including:

[0073] An embedded processor; an electrical stimulation current generation module, connected to the embedded processor, for generating N independent pulse currents based on the control signals of the embedded processor, where N is an integer greater than or equal to 1; an electrode array, containing N electrode pads, connected to the output of the electrical stimulation current generation module, for applying the pulse current to the human body; a real-time current monitoring module, connected to the electrode array and the embedded processor, for real-time monitoring of the amplitude of the pulse current flowing through each electrode pad and generating a first feedback signal to the embedded processor; an electrical stimulation effect detection module, connected to the embedded processor, for detecting the body's response signals under electrical stimulation and generating a second feedback signal to the embedded processor; and a human-machine interaction module, connected to the embedded processor, for displaying system status information and interacting with the user; wherein, the embedded processor is configured to: adjust the control signals output to the electrical stimulation current generation module in real time based on the first and second feedback signals to form a closed-loop control system, thereby dynamically adjusting the parameters of the pulse current.

[0074] The ventral epidural region of the spinal cord refers to a specific anatomical area located outside the ventral dura mater of the spinal cord. It is commonly used for electrical stimulation to influence motor neural pathways, enabling precise targeted stimulation to modulate neural activity and improve motor function. An electrode array refers to a collection of multiple electrode pads used to directly apply electrical stimulation to human tissue. For example, current can be transmitted to the ventral epidural region of the spinal cord through implantation or attachment to achieve precise multi-target neuromodulation. The first feedback signal can be an electrical signal representing real-time monitored current amplitude data. For example, it is sampled and converted into a digital signal by an ADC from a real-time current monitoring module and transmitted to a processor for adjusting stimulation parameters in closed-loop control. The second feedback signal can be an electrical signal representing detected human bodily responses. For example, it is generated by a sensor output processed by an electrical stimulation effect detection module, allowing for comparison with expected results to optimize the stimulation strategy. The control signal can be an electronic signal output by an embedded processor, used to drive the electrical stimulation current generation module for precise control of pulse current generation. The parameters of the pulse current can refer to its characteristic values, such as frequency, pulse width, and amplitude. These are calculated using embedded processor algorithms and output to the electrical stimulation current generation module for customized stimulation to match individual needs. System status information refers to data during system operation, such as current amplitude, bodily responses, and alarm status. This data is displayed on a touchscreen via a human-machine interface module, allowing users to monitor system performance and safety in real time. User commands refer to user-inputted commands or settings, such as target stimulation parameters and safety thresholds. These are received and transmitted to the embedded processor via a touchscreen or wireless channel for customizing control behaviors and intervening in system operation.

[0075] As a concrete example: the overall circuit is as follows Figure 1As shown, the entire system operates under the control of an embedded microprocessor chip (the microprocessor chip has a microprocessor, which corresponds to the aforementioned embedded processor). The on-chip peripheral resources of the microprocessor chip mainly include timers, I / O (input / output port) devices, and two ADCs (analog-to-digital converters ADC0 and ADC1). These peripherals are accessed and controlled by the kernel according to software code.

[0076] The microprocessor, based on the preset or actual required frequency and pulse width of the pulse stimulation current, and according to the timer count, outputs N pulse-width modulation (PWM) signals (PWM1, PWM2, PWM3, ..., PWMN) with different frequencies and pulse widths from the corresponding I / O ports. Because the microprocessor is a digital system, the amplitude of all PWM signals is fixed, determined by the logic high level of the selected microprocessor chip's I / O pins (common microprocessors typically use 5V or 3.3V logic high levels, such as the 3.3V logic level of STM32 series embedded microprocessors). Therefore, to control the amplitude of the PWM signals, the N PWM signals output by the processor are input to N amplitude modulators. The voltage gain of the amplitude modulator (also known as: voltage amplification factor = output signal amplitude ÷ ...) is... The amplitude of the input signal is controllable. The voltage gain of the N amplitude modulators is controlled by the amplitude control (AC) signals (AC1, AC2, AC3, ..., ACN) output from the processor's I / O port. In this way, the system realizes the generation of N voltage signals with controllable frequency, pulse width, and amplitude. The electrical signal to be applied to the electrodes is the current signal with corresponding parameters. It is necessary to ensure that the load human body connected to the electrodes does not affect the amplitude of the stimulation current. Each electrode needs to be connected to the output terminal of a voltage-controlled current source. The output current of the voltage-controlled current source is only controlled by its input voltage and is not affected by the load connected to the end electrode. Therefore, the frequency, pulse width, and amplitude controllable voltage signals output by the amplitude modulators are connected to the input terminal of the voltage-controlled current source, ultimately providing the electrodes with a stimulation current with controllable frequency, pulse width, and amplitude.

[0077] An N-channel voltage sampler and follower, a single-pole multi-throw (SPMD) analog switch (1×N), and a low-pass filter constitute a real-time electrode current monitoring system to ensure that each stimulation current remains within a safe range. Each voltage sampler and follower first obtains a voltage signal (the voltage across the sampling resistor) from the corresponding electrode through a sampling resistor, which is then input to its follower. The follower acts as an isolation and buffer, preventing subsequent circuitry (such as the SPMD analog switch and low-pass filter) from affecting the electrode current. The output signal of each voltage sampler and follower is a voltage pulse signal with the same frequency, pulse width, and amplitude as the corresponding electrode, proportional to the stimulation current (usually the proportionality coefficient is the resistance value of the sampling resistor). This signal is then processed by the on-chip analog-to-digital converter (ADC0) of the processor chip. The converter can sample and convert the voltage pulse signal from digital to analog, thus measuring the amplitude of the voltage pulse signal. The processor then performs proportional conversion to obtain the pulse amplitude of the corresponding stimulation current. However, due to the limited resources of the processor chip's analog-to-digital converter (ADC), it cannot simultaneously sample and convert the output voltage signals of N followers. Therefore, a 1×N single-pole multi-throw analog switch is connected after the voltage sampler and follower. This switch, under the control of the switch control (SWC) signal (SWC0) output from the microprocessor I / O port, sequentially selects (switches) the output signals of the voltage sampler and follower in time sequence. Because the output signals of the voltage sampler and follower... It is a pulse signal with a certain frequency and width (pulse signal = DC component + AC component). Obviously, it is not a reasonable approach to directly obtain its pulse amplitude from the ADC. Therefore, a low-pass filter is connected to the common terminal of the single-pole multi-throw switch. The output signal of the low-pass filter is the DC component of the selected voltage sampler and follower. Then, the ADC0 obtains the DC component output by the corresponding voltage sampler and follower. The microprocessor calculates the amplitude of the voltage pulse signal output by the corresponding voltage sampler and follower based on the relationship between the DC component of the pulse signal and the pulse duty cycle (DC component = pulse amplitude × duty cycle, duty cycle = pulse width ÷ pulse period = pulse width × pulse frequency), and then further calculates the amplitude of the stimulation current of the corresponding electrode.

[0078] To achieve the desired stimulation effect, the system can detect bodily responses such as posture, muscle reactions, and motor awareness under electrical stimulation in real time and adjust the parameters of the electrical stimulation current accordingly, thus forming a closed-loop electrical stimulation control system. For example, when insufficient bodily response or abnormal posture is detected, the pulse amplitude or firing sequence of the corresponding channel is automatically adjusted to increase or decrease the current stimulation. These bodily responses are sensed by corresponding vital sign sensors, which output corresponding voltage signals. Because the voltage signal range of most sensors cannot directly meet the sampling range of the ADC, the voltage signal output by the vital sign sensors must undergo signal (voltage) conditioning circuitry for signal processing such as voltage differential amplification. This ensures that the output signal range of the conditioning circuit maximizes the compatibility with the ADC's sampling range. For example, if the voltage sampling range of an ADC is 0~3.3V, the signal (voltage) conditioning circuit needs to linearly adjust the output voltage range of the corresponding sensor to 0~3.3V. This ensures that the entire sensing signal value can be detected and improves the sensitivity of the ADC to signal sampling. Similarly, due to the limited on-chip ADC resources of the microprocessor chip, it is not possible to process all signals (electrical signals) within the ADC. The output signal of the voltage conditioning circuit is sampled simultaneously. Therefore, a 1×M single-pole multi-throw analog switch is connected after the voltage conditioning circuit. Under the control of the switch control signal (SWC1) output from the microprocessor I / O port, the switch sequentially selects (switches) the output signal of the voltage conditioning circuit in time sequence. The common terminal of the single-pole multi-throw analog switch is connected to ADC1, thus realizing the sequential sampling of the sensing signals of the vital signs sensor. The processor calculates the output voltage of the corresponding vital signs sensor based on the ADC sampling value and the signal transmission characteristics of the voltage conditioning circuit. Furthermore, based on the sensing characteristics of the sensor, it calculates the corresponding physical quantities of the bodily response (such as pressure, amplitude of movement, electrical stimulation response rate, body position, motor consciousness, etc.). Finally, based on these physical quantities of bodily response, the processor adjusts the frequency, pulse width, and amplitude of the electrical stimulation pulse current in real time to achieve the expected electrical stimulation effect.

[0079] Additionally, it should be noted that this invention is for ventral epidural electrical stimulation, not dorsal epidural electrical stimulation; the parameters for the two are significantly different, as shown in the table below:

[0080]

[0081] The beneficial effects of one of the embodiments in this specification include at least the following: by using a microprocessor to generate multi-channel pulse width modulation signals, and after amplitude adjustment, driving a voltage-controlled current source, the output stimulation current with adjustable frequency, pulse width, and amplitude is applied to the ventral spinal cord neural structures. Real-time monitoring of the stimulation current in each channel is achieved through a combination of voltage sampling and a single-pole multi-throw analog switch. Simultaneously, feedback information from multimodal sensors such as body position, electromyography, and pressure is integrated to construct a closed-loop control mechanism, enabling dynamic adjustment and individualized optimization of electrical stimulation parameters. Compared with existing dorsal electrical stimulation neuromodulation schemes, this invention establishes a parameter-targeted regulation system for the first time targeting the ventral region of the spinal cord, enhancing the precise activation ability of motor and autonomic nerve functions. It has advantages such as more accurate electrical stimulation positioning, more sensitive response, and more intelligent control, and is suitable for intelligent rehabilitation intervention in scenarios such as spinal cord injury, cerebral palsy, and neurological dysfunction.

[0082] In some implementations, the electrical stimulation current generation module includes: N amplitude modulators, whose input terminals respectively receive N fixed-amplitude PWM signals generated by an embedded processor, and whose control terminals receive control signals from the embedded processor, for outputting N PFWHMn voltage signals with adjustable frequency, pulse width, and amplitude; and N voltage-controlled current sources, whose input terminals are respectively connected to the output terminals of the N amplitude modulators, for converting the PFWHMn voltage signals into corresponding pulse currents, and the amplitude of the pulse currents is not affected by the back-end load.

[0083] An amplitude modulator can refer to an electronic circuit unit used to adjust the amplitude of an input signal. For example, it can divide a PWM signal using a digital potentiometer and buffer it through a preset operational amplifier to output a PFWHMn voltage signal, used to independently control the amplitude parameters of each stimulation current. The signal output by the amplitude modulator is a voltage pulse signal whose pulse frequency, width, and amplitude (pulse height) are all adjustable; here, we call it the PFWHMn (Pulse-Frequency-Width-Height-Modulation) signal. A voltage-controlled current source can refer to a circuit that is voltage-controlled and outputs a stable current, capable of converting an input voltage signal into a constant current unaffected by the load. A pulsed current can refer to a current output in pulse form, with specific frequency, pulse width, and amplitude parameters, capable of safely and effectively activating neural tissue.

[0084] In some implementations, the amplitude regulator includes a digital potentiometer and a first operational amplifier; the two ends of the digital potentiometer receive a PWM signal and a ground signal respectively, and its taps are controlled by a control signal to divide the PWM signal; the first operational amplifier constitutes a voltage follower, its input is connected to the taps of the digital potentiometer, and its output outputs the PFWHMn voltage signal.

[0085] A digital potentiometer can refer to an electronic component whose resistance value can be adjusted via a digital signal, used for precise voltage division of an input PWM signal. A first operational amplifier can refer to the first instance of an operational amplifier in a circuit, used for signal buffering and driving, capable of stably transmitting the PFWHMn voltage signal with high input impedance and low output impedance. A voltage follower can refer to an operational amplifier circuit configuration whose output voltage follows the input voltage, used to isolate preceding and following circuits and enhance load-driving capability. A tap can refer to a movable electrical contact on a potentiometer, used to select a portion of the voltage from the resistive element, enabling digital adjustment of the resistance value.

[0086] In some implementations, the voltage-controlled current source includes a sampling resistor, an operational amplifier, and a high-precision instrumentation amplifier, wherein a gain resistor R is connected between the two input terminals of the instrumentation amplifier. G The output of the instrumentation amplifier is connected to the corresponding electrode plate via a sampling resistor. Its non-inverting input receives the PFWHMn voltage signal, and its inverting input is grounded. The output and inverting input of the operational amplifier are both connected to the reference voltage terminal of the instrumentation amplifier, and its non-inverting input is connected to the corresponding electrode plate. The operational amplifier forms a voltage follower. The stimulation current In applied to the electrode plate and the voltage signal PFWHMn output by the amplitude modulator satisfy the following relationship:

[0087]

[0088] Among them, A G R is the voltage gain of the instrumentation amplifier. AD It is the resistance value of the internal resistor of the chip, R. G Rs is the resistance value of the gain resistor, and Rs is the resistance value of the sampling resistor.

[0089] A sampling resistor can refer to a resistive element used to measure current. It reflects the current value by measuring the voltage drop across its terminals, providing a current feedback signal to ensure the accuracy and safety of the stimulation current. An operational amplifier can refer to a high-gain differential amplifier electronic component used for signal amplification, filtering, and mathematical operations. It can buffer signals and drive loads to ensure stable voltage transmission. A high-precision instrumentation amplifier can refer to a high-performance amplifier specifically designed for accurately amplifying differential signals, featuring high common-mode rejection ratio and low drift. For example, it uses high-performance amplifier chips to accurately amplify small differential voltage signals and suppress common-mode noise. A gain resistor can refer to an external resistor used to set the amplifier gain, precisely controlling the amplifier's amplification factor. An electrode pad can refer to a conductive element that contacts human tissue for applying electrical stimulation, enabling targeted delivery of the stimulation.

[0090] In some embodiments, the voltage-controlled current source includes a first operational amplifier, a second operational amplifier, a transistor, a first resistor, a second resistor, and a sampling resistor. The output of the first operational amplifier is connected to the base of the transistor, its non-inverting input receives the PFWHMn voltage signal, and its inverting input is connected to the output of the second operational amplifier. The non-inverting input of the second operational amplifier is connected to the emitter of the transistor, and its inverting input is connected to the inverting input of the first operational amplifier via the first resistor and grounded via the second resistor. The first and second operational amplifiers constitute a deep negative feedback circuit. The collector of the transistor is connected to the corresponding electrode plate, and its emitter is grounded via the sampling resistor. The stimulation current In applied to the electrode plate and the voltage signal PFWHMn output by the amplitude modulator satisfy the following relationship:

[0091]

[0092] Where R1 and R2 are the resistance values ​​of the first resistor and the second resistor, respectively, and Rs is the resistance value of the sampling resistor.

[0093] The first operational amplifier can refer to the first instance of an operational amplifier in the circuit, used for signal amplification and processing, and can form part of a deep negative feedback loop to stabilize the control loop. The second operational amplifier can refer to the second instance of an operational amplifier in the circuit, used to monitor the emitter voltage and participate in the negative feedback. The first resistor can refer to the first specific resistive element in the circuit, used to set the feedback coefficient, and can work with the second resistor to determine the circuit transfer ratio. The second resistor can refer to the second specific resistive element in the circuit, and can work with the first resistor to set the voltage division ratio of the feedback network.

[0094] In some implementations, the real-time current monitoring module includes: N voltage sampling and follower units, each unit being used to acquire the voltage across the sampling resistor in the corresponding electrode circuit and output a voltage pulse signal proportional to the pulse current; a single-pole multi-throw analog switch, whose multiple input terminals are respectively connected to the output terminals of the N voltage sampling and follower units, and whose control terminal is controlled by an embedded processor to sequentially select voltage pulse signals; and a low-pass filter connected to the output terminal of the single-pole multi-throw analog switch to extract the DC component of the selected voltage pulse signal; wherein, the embedded processor is connected to the output terminal of the low-pass filter and is configured to calculate the amplitude of the pulse current based on the DC component and the known frequency and pulse width of the corresponding pulse current.

[0095] A single-pole multi-throw (SPMWH) analog switch can refer to a type of multiplexer switch used to select multiple input signals, enabling time-division multiplexing of multiple signals by sequentially switching channels. The control terminal refers to the control signal input port of the SPMWH analog switch, used to sequentially select multiple signals. The DC component refers to the constant or slowly changing voltage portion of the signal, which can be used to calculate the amplitude of pulse current.

[0096] In some embodiments, the low-pass filter includes a first capacitor, a second capacitor, a sixth operational amplifier, a fourth resistor, a fifth resistor, and a sixth resistor. The first terminals of the first and second capacitors are respectively connected to the two ends of the fourth resistor, and the second terminals of both capacitors are grounded. The first terminal of the fourth resistor is connected to the output terminal of a single-pole multi-throw analog switch, and its second terminal is connected to the non-inverting input terminal of the sixth operational amplifier. The inverting input terminal of the sixth operational amplifier is grounded via the fifth resistor and connected to its output terminal via the sixth resistor. Its output terminal is connected to an ADC in an embedded processor.

[0097] The first capacitor can refer to a specific capacitor element in the circuit, which works in conjunction with the second capacitor to achieve multi-stage filtering and enhanced high-frequency attenuation. The second capacitor can refer to another specific capacitor element in the circuit, which can further smooth the signal and provide additional filtering order. The sixth operational amplifier can refer to a sixth instance of an operational amplifier in the circuit, used to enhance signal driving capability and provide gain. The fourth resistor can refer to a fourth specific resistor element in the circuit, which, together with the capacitor, determines the cutoff frequency of the low-pass filter. The fifth resistor can refer to a fifth specific resistor element in the circuit, which determines the amplifier's input impedance and DC bias point. The sixth resistor can refer to a sixth specific resistor element in the circuit, which, together with the fifth resistor, determines the voltage gain of the non-inverting amplifier. An ADC in an embedded processor can refer to an analog-to-digital converter module integrated within the embedded processor, such as a successive approximation ADC that converts the analog voltage output from the low-pass filter into a digital value, providing a digital signal for the processor to calculate the current amplitude.

[0098] In some implementations, the electrical stimulation effect detection module includes: at least one vital sign sensor for detecting the physical response of a human body to electrical stimulation; a signal conditioning circuit connected to the vital sign sensor for conditioning the signal output by the vital sign sensor to the sampling range of the analog-to-digital converter of the embedded processor; and a single-pole multi-throw analog switch with multiple inputs connected to the outputs of one or more signal conditioning circuits, the control of which is controlled by the embedded processor for sequentially selecting the conditioned vital sign signals.

[0099] Vital signs sensors refer to sensing devices used to detect physiological or physical parameters, capable of detecting responses such as body position, muscle activity, or movement intention through adhesive or implantation methods. Signal conditioning circuitry refers to electronic circuitry that preprocesses the sensor signals, adjusting the raw signals to the ADC input range to ensure accurate sampling. The output signal of a vital signs sensor refers to the raw electrical signal detected by the sensor, typically a weak and noisy voltage or current signal, such as the microvolt-level signal output by an electromyography (EMG) sensor or the millivolt-level voltage output by a pressure sensor; it requires conditioning before being used by the processor.

[0100] In some implementations, the embedded processor is specifically used to: receive target stimulation parameters and / or safety thresholds set by the user through a human-machine interaction module; compare the current amplitude fed back by the real-time current monitoring module with the safety threshold, and if it exceeds the range, issue an alarm or automatically cut off the output; compare the body response signal fed back by the electrical stimulation effect detection module with the expected effect, and automatically adjust at least one parameter among the frequency, pulse width, and amplitude of the pulse current based on a preset control algorithm, so that the body response signal approaches the expected effect.

[0101] User-defined target stimulation parameters refer to the desired stimulation parameter values ​​input by the user through the human-computer interaction module, such as target values ​​for pulse frequency, pulse width, and amplitude. The embedded processor obtains these values ​​by parsing the user interface input and uses them as setpoints for closed-loop control to guide parameter adjustments. Safety thresholds refer to parameter limits set to ensure safety, such as upper and lower limits for current amplitude. These are set by the user and stored in the processor's memory, triggering protective actions when an anomaly is detected. The current amplitude fed back by the real-time current monitoring module refers to the actual current measurement value obtained from the current monitoring module, used to compare with the safety threshold to verify stimulation safety. Preset adjustment algorithms refer to the control program stored in the processor, which calculates parameter adjustments based on the difference between the body's response signal and the expected effect, enabling automatic optimization of stimulation parameters.

[0102] In some implementations, the human-computer interaction module includes a local interaction unit and / or a remote interaction unit; the local interaction unit is a touch screen integrated on the system; the remote interaction unit is a wireless communication module, which includes a Bluetooth module or a Wi-Fi module, for data interaction with an external mobile terminal or a remote server to achieve remote monitoring and parameter setting.

[0103] External mobile terminals can refer to portable smart devices held by users, such as smartphones or tablets with dedicated control applications installed, enabling remote operation of the neuromodulation system via wireless connection.

[0104] In some implementations, interacting with the user through the human-computer interaction module includes receiving instructions via a local touchscreen and / or receiving instructions from a remote terminal via a wireless communication channel.

[0105] In some implementations, the vital signs sensor includes sensors for detecting body position, muscle pressure, electromyographic signals, or motor awareness.

[0106] Posture detection refers to the process of identifying and measuring body posture or position, such as detecting spatial orientation changes of the trunk and limbs using accelerometers or gyroscopes to provide postural data for evaluating stimulation effects and adjusting parameters. Muscle pressure refers to the physical pressure exerted on muscle tissue, such as measuring changes in surface pressure during muscle contraction using piezoelectric or resistive pressure sensors, reflecting muscle activation and contraction strength. Electromyography (EMG) signals refer to the bioelectrical signals generated by muscle electrical activity, such as the amplitude and frequency characteristics of EMG signals acquired through surface electrodes or needle electrodes, used to assess neuromuscular activation levels and fatigue states. Motor awareness refers to the neural activity that generates the intention to move, such as the motor preparation potential obtained by decoding EEG signals or motor cortex signals, which can serve as a higher-level control signal to trigger or modulate electrical stimulation patterns.

[0107] In some implementations, the voltage sampling and follower unit includes a third operational amplifier, a fourth operational amplifier, a fifth operational amplifier, and four third resistors of the same value. The non-inverting input of the third operational amplifier is connected to the first end of the sampling resistor, its inverting input is connected to its output, and is connected to the non-inverting input of the fifth operational amplifier via the first third resistor. The non-inverting input of the fourth operational amplifier is connected to the second end of the sampling resistor, its inverting input is connected to its output, and is connected to the inverting input of the fifth operational amplifier via the second third resistor. The non-inverting input of the fifth operational amplifier is grounded via the third third resistor, its inverting input is connected to its output via the fourth third resistor, and its output is connected to the input terminal corresponding to a single-pole multi-throw analog switch. The third and fourth operational amplifiers constitute a voltage follower. The fifth operational amplifier and the four third resistors of the same value constitute a differential amplifier circuit with a voltage gain of 1.

[0108] Clearly, the output voltage can be expressed as:

[0109]

[0110] Where Von represents the voltage at the output of the fifth operational amplifier, i.e., the voltage difference across the sampling resistor; Vs1 is the voltage across the first terminal of the sampling resistor; Vs2 is the voltage across the second terminal of the sampling resistor; and R... SVon is the resistance value of the sampling resistor, and In is the stimulation current value (amplitude) through the sampling resistor. From the above formula, we know that as long as Von is measured, the current stimulation current In can be calculated.

[0111] The third operational amplifier can refer to the third instance of an operational amplifier in the circuit, used to sample the voltage across one end of the sampling resistor with high impedance. The fourth operational amplifier can refer to the fourth instance of an operational amplifier in the circuit, capable of sampling the voltage across the other end of the sampling resistor with high impedance. The fifth operational amplifier can refer to the fifth instance of an operational amplifier in the circuit, amplifying the voltage difference across the sampling resistor. The third resistor can refer to the third instance of a resistor in the circuit, used to construct a differential amplifier circuit with a gain of 1.

[0112] The present invention will be further described below with reference to a detailed embodiment:

[0113] Under software operation, the microprocessor outputs multiple (N) PWM signals with individually adjustable frequency and pulse width via I / O pins, based on the timing value of a single on-chip general-purpose timer. The smallest unit (time resolution) for the PWM pulse width and period parameters (frequency parameters) is 1μs to meet the frequency parameter requirements.

[0114] 10~120Hz (period parameter) The requirement is for a pulse width parameter that is precisely adjustable from 150 to 500 μs (-0.1 s). The specific principle and method for generating PWMn (n=1,2,3,…,N) are as follows:

[0115] Define the clock frequency of the time reference clock source used for timer counting as f. Tclock The clock period is T Tclock Then T Tclock = ,T Tclock The value is the time resolution of the timer (the smallest unit of time resolution).

[0116] For example, the maximum f of the four general-purpose timers (TIMx, x=2,3,4,5) of the STM32F1 series microprocessor with the ARM Cortex-M3 core. Tclock With a clock speed of 72MHz, it is perfectly adequate for microsecond-level timing functions. This system uses an STM32F1 series processor to generate the PWMn signal and process and control other signals.

[0117] To achieve timing with a 1μs time resolution, the value of the auto-reload register (TIMx_ARR) of a pre-used general-purpose timer on the microprocessor chip is set by software to (f Tclock / 1000000) uses an up-counting mode, so whenever the value of the counter (TIMx_CNT) increases from 0 to (f TclockWhen the timer reaches 1000000, the counter (TIMx_CNT) restarts counting from 0 and generates a timer interrupt event. Therefore, the time interval (period) for one timer interrupt event is...

[0118]

[0119] It is the clock cycle. It is the clock frequency.

[0120] In the control program, an unsigned integer global variable `Int_count` can be defined to record the number of interrupts. Its initial value is 0; that is, in the timer interrupt service routine, `Int_count` increments by 1 each time a timer interrupt occurs (each time the interrupt service routine is entered). Its maximum value is set to 999999, meaning that when `Int_count > 999999`, `Int_count` starts counting from 0 again. Therefore, the maximum timer duration obtained from `Int_count` is 1 second, and the increment step is... .

[0121] Define the frequency of the PWMn signal as The period is The system requires a frequency adjustable range of 10Hz. <120Hz. Then the period = Adjustable range is s< <0.1s. The pulse width of the PWMn signal is defined as... The system requires its adjustable range to be [range]. Calculate the PWMn level value. The formula is as follows:

[0122] (1)

[0123] It is the level value of the PWMn signal. It is the pulse width of the PWMn signal. It is the frequency of the PWMn signal.

[0124] In the above formula, "1" and "0" represent the high and low voltage levels of the microprocessor (3.3V and 0V), respectively, and "%" represents the remainder of the variable. Based on the above formula, the PWMn signal can be generated by editing software code in the microprocessor's interrupt service routine or main function program.

[0125] Within one pulse cycle, if the time point falls within the "pulse width" time, the output is high (1, i.e., 3.3V); otherwise, the output is low (0, i.e., 0V).

[0126] The function of the amplitude modulator is to adjust the amplitude of the PWMn signal. Specifically, under the control of the microprocessor's output signal ACn (n=1,2,3,…,N) corresponding to the I / O device, the fixed amplitude (also called pulse height) of the PWMn signal (3.3V) can be adjusted within the range of 0~3.3V. Therefore, under the control of the microprocessor, the signal output by the amplitude modulator is a voltage pulse signal with adjustable pulse frequency, width, and amplitude (pulse height). Here, we call it the PFWHMn (Pulse-Frequency-Width-Height-Modulation) signal. In this method, its circuit is designed using a digital potentiometer chip and an operational amplifier chip. Its schematic diagram is shown below. Figure 2 As shown.

[0127] Figure 2 In this circuit, the digital potentiometer chip forms a controllable voltage divider circuit, and the operational amplifier chip forms a voltage follower. The output voltage of the follower is always consistent with its input voltage, which plays the role of isolation and buffering to avoid the influence of the input impedance of the subsequent circuit (such as the voltage-controlled current source) on the voltage divider circuit.

[0128] On-chip voltage divider resistors (on-chip potentiometer) of digital potentiometer chips One end is connected to the PWMn signal output by the microprocessor, and the other end is grounded (GND). The voltage divider taps are controlled by the on-chip tap control logic unit to achieve controllable voltage division of the PWMn signal.

[0129] The basic control process of voltage divider is as follows: the tap control logic unit receives the ACn instruction from the microprocessor and controls... The tap position corresponds to different voltage division ratios k = 0~1. For example, when the tap is located at GND (tap and GND are short-circuited), the voltage division ratio k = 0; when the tap is located at PWMn (tap and PWMn are short-circuited), the voltage division ratio k = 1. The relationship between the voltage division value PFWHMn and PWMn is: PFWHMn = Thus, under the control of the microprocessor, a voltage pulse signal with adjustable pulse frequency, width, and amplitude (pulse height) can be realized.

[0130] Note that the voltage division adjustment accuracy of a digital potentiometer depends on the bit depth (precision) of the selected chip. For example, with 8-bit precision, the taps only have 28 voltage division values. Furthermore, many commercially available digital potentiometer chips do not use ordinary parallel digital I / O ports for their control interfaces (ACn), but rather serial interfaces to reduce hardware interface resources. For example, high-precision commercial digital potentiometer chips like the AD5290 / AD520BRZ10 and MAX5423 / 5433 / 5438 use IIC interfaces to control the potentiometer taps. In this case, it is necessary to design the control interface between the selected chip and the microprocessor. According to the interface protocol, the timing of the microprocessor's I / O ports can be programmed via software to achieve effective communication between the microprocessor and the digital potentiometer, thereby enabling effective control of the digital potentiometer. Regarding the selection of operational amplifier chips, based on the required pulse width and frequency, an operational amplifier with a suitable operating frequency and bandwidth should be chosen. That is, the operational amplifier's operating frequency band and bandwidth should be able to respond to pulse signals of the corresponding frequency and pulse width. For pulse signals with frequencies of 10~120Hz and pulse widths of 150~500μs, most commercial operational amplifiers can meet the requirements.

[0131] The function of a voltage-controlled current source is to convert a voltage signal into a stimulation current signal. A fundamental characteristic of a current source is that its output current is unaffected by the connected load. In this system, the following two schemes are used to implement the voltage-controlled current source.

[0132] Option 1: Use an instrumentation amplifier chip such as the AD620 to implement a high-precision voltage-controlled current source. Its circuit principle is as follows: Figure 3 As shown.

[0133] Figure 3 In this context, RG is the gain resistor of the instrumentation amplifier, and REF is the reference voltage V of the instrumentation amplifier. REF The pin Rs is called the sampling resistor, In is the stimulation current applied to the corresponding electrode n, Vs and Vn are the voltages across Rs relative to ground, and the operational amplifier forms a voltage follower circuit.

[0134] (2)

[0135] V REF Vs is the reference voltage of the instrumentation amplifier, Vn is the voltage at the first terminal of Rs, and Vn is the voltage at the second terminal of Rs.

[0136] Based on the characteristics of the instrumentation amplifier, we know

[0137] (3)

[0138] PFWHMn is the voltage pulse signal output by the amplitude regulator, which is an adjustable pulse frequency, width, and amplitude (pulse height). AG is the voltage gain of the instrumentation amplifier.

[0139] in, This is the voltage gain of the instrumentation amplifier. Because the input impedance of the voltage follower formed by the operational amplifier is approximately infinite, the input current is approximately zero (virtual open circuit). Therefore, the current Is flowing through Rs is equal to the electrode stimulation current In.

[0140] (4)

[0141] In is the electrode stimulation current, Rs is the sampling resistor, and Is is the current flowing through Rs.

[0142] Substituting equations (2) and (3) into equation (4) yields...

[0143] (5)

[0144] As can be seen from equation (5) above, in Rs and R G Under fixed conditions, the stimulation current applied to the electrodes is controlled only by the voltage signal PFWHMn output by the amplitude modulator, and is independent of the load connected to the electrodes, thus realizing voltage-to-current control. In this system, the amplitude of the stimulation current is required to be 0.1~10.0 mA, that is, the maximum stimulation current amplitude corresponding to the maximum value of PFWHMn 3.3V is 10mA. Therefore, Rs and R can be selected according to equation (5). G The resistance value is used to ensure the amplitude of the stimulation current; if R is not connected... G (i.e. R) G =∞), choosing a resistor with Rs=0.33kΩ will ensure the required amplitude of the stimulation current.

[0145] Option 2: Implement a voltage-controlled current source using a common operational amplifier and a low-power NPN or NMOS transistor. The circuit diagram is as follows: Figure 4 As shown.

[0146] Figure 4In this circuit, the output of operational amplifier 1 (i.e., the first operational amplifier) ​​is connected to the base of a transistor (or the gate of an NMOS transistor), and the emitter of the transistor (or the source of an NMOS transistor) is grounded through the sampling resistor Rs. Is is the current flowing through Rs, VCC is the voltage source applying a positive voltage, and In is the stimulation current applied to the electrode. Operational amplifier 2 (i.e., the second operational amplifier), R1 (i.e., the first resistor), and R2 (i.e., the second resistor) form a co-inverting amplifier, amplifying the sampled voltage Vs in phase and feeding it back to the inverting input of operational amplifier 1. Therefore, both operational amplifiers operate in a deep negative feedback state, satisfying the conditions of "virtual short" (i.e., the voltages at the non-inverting and inverting inputs of the operational amplifier are approximately equal, approximating a "short circuit") and "virtual open" (i.e., the input impedances at both inputs of the operational amplifier are infinite, approximating an "open circuit").

[0147] (6)

[0148] V1 is the voltage between the second terminal of operational amplifier 1 and the third terminal of operational amplifier 2, and V2 is the voltage between the second terminal of operational amplifier 2 and resistor R2.

[0149] Therefore, we can solve equation (6) to obtain...

[0150] (7)

[0151] Because the base current of a transistor (or the gate current of an NMOS transistor) is extremely small compared to the collector-emitter current (or the drain-source current of an NMOS transistor), and because the non-inverting input of operational amplifier 2 is "virtually open," therefore...

[0152] (8)

[0153] As can be seen from equation (8), under the condition that R1, R2 and Rs are fixed, the stimulation current applied to the electrode is only controlled by the voltage signal PFWHMn output by the amplitude regulator, and has nothing to do with the biological body (load) connected to the electrode, thus realizing the control of current by voltage. In this system, the maximum stimulation current amplitude corresponding to the maximum value of PFWHMn 3.3V is required to be 10mA. Therefore, according to equation (8), the resistance values ​​of R1, R2 and Rs can be selected to ensure the amplitude of the stimulation current. For example, if R1 is short-circuited (i.e. R1=0Ω) and R2 is open-circuited (i.e. R2=∞), the operational amplifier 2 forms a voltage follower. By selecting a resistor of Rs=0.33kΩ, the amplitude requirement of the stimulation current can be guaranteed.

[0154] When comparing the above two schemes, Scheme 1 has relatively higher precision, while Scheme 2 has lower cost. Each of the two schemes has its own advantages. The operational amplifiers in both schemes can meet the requirements of system signal frequency, pulse width and other parameters by using most common commercial devices; the small power devices with a saturation current of dozens of milliamperes should be used for the crystal triodes in Scheme 2.

[0155] In order to monitor the stimulation current applied to the electrode in real time, a resistor needs to be connected in series in the stimulation current branch, and then the terminal voltage across the resistor is measured. According to Ohm's law, the stimulation current is calculated. This resistor is called the sampling resistor, and the process of obtaining the terminal voltage of this resistor is called voltage sampling. In the two schemes of the voltage-controlled current source, there is a sampling resistor Rs in the stimulation current branch. In order not to increase the circuit scale and complexity, there is no need to connect an additional sampling resistor in series in the stimulation current branch here, but the sampling voltage is directly obtained from both ends of Rs. The voltage sampling and the principle circuit of the follower are as Figure 5 shown.

[0156] Figure 5 In the figure, operational amplifiers 3 (i.e., the third operational amplifier) and 4 (i.e., the fourth operational amplifier) respectively form voltage followers, following the voltages Vs1 and Vs2 to the ground across the sampling resistor, and at the same time playing the role of isolation and buffering to avoid the influence of the input impedance of the subsequent circuit on the stimulation current In; operational amplifier 5 (i.e., the fifth operational amplifier) and four resistors R3 with the same resistance value (i.e., the third resistor) form a differential amplification circuit, and its voltage gain (differential voltage amplification factor) is 1. Usually, the resistance value of R3 is selected in the order of KΩ. According to the conditions of "virtual short" and "virtual open" when the operational amplifier is in deep negative feedback, the output voltage Von of the voltage sampling and the follower can be expressed as

[0157] (9)

[0158] As can be seen from the above formula (9), as long as Von is measured, the current stimulation current In can be calculated.

[0159] The function of the single-pole multi-throw analog switch (1×N) is to sequentially select and measure the output voltage Von of the voltage sampling and the follower through multiplexing. If the number of multiplexing channels of a single switch chip is greater than or equal to N, a single chip can be used, such as the CD4051B analog switch chip, which has 8 multiplexing channels. If , a single CD4051B chip can be used to achieve the function. If the number of multiplexing channels of the selected analog switch chip (assuming the number of channels is K, and K is generally an integer power of 2) is less than N (K < N), then multiple analog switch chips need to be connected in parallel to realize the 1×N single-pole multi-throw analog switch. The principle circuit is as Figure 6 shown.

[0160] Figure 6 In this design, each analog switch chip requires at least one channel pin to be left floating, as shown by the "×" symbol in the figure. This ensures that when all channels on the chip are not selected, the switch's "pole" must be placed on the floating pin. Under the control of the switch control signal SWC0 output from the microprocessor's I / O port, N signals are selected sequentially, achieving N-way multiplexing. Alternatively, if the required number of bits for SWC0 (corresponding to the number of I / O port pins of the microprocessor) is too large, a digital decoder can be designed between the microprocessor and the switch control pin of the single-pole multi-throw analog switch to save microprocessor I / O pin resources, enabling sequential selection of the N signals.

[0161] Since the Von (n=1,2,3,...,N) signal is a voltage signal with a certain frequency and pulse width synchronized with the stimulation current In signal, especially when its pulse width is very small, directly sampling Von with an analog-to-digital converter (ADC) may fail to capture the signal pulse. Therefore, it is more reasonable to use an ADC to acquire the DC component of the signal and then calculate the pulse amplitude based on the pulse frequency, duty cycle, and the mathematical relationship between the DC component and the pulse. A low-pass filter is an effective method to obtain the DC component of the pulse signal; its circuit principle is as follows: Figure 7 As shown.

[0162] Figure 7 In the circuit, resistor R (the fourth resistor) and two capacitors C (the first and second capacitors) form a π-type low-pass filter circuit to obtain the DC component of Von. Operational amplifier 6 (the sixth operational amplifier), resistors R5 (the fifth resistor), and R6 (the sixth resistor) form a non-inverting amplifier circuit (whose voltage gain is...). Its function is to linearly amplify the DC component of Von to the range of 0~3.3V, satisfying the voltage sampling range of ADC0, thereby ensuring the sampling sensitivity of ADC0.

[0163] In this system, the minimum frequency of the pulse signal is 10Hz. To ensure that the low-pass filter can effectively filter out (suppress) the AC components of all signals, the cutoff frequency of the low-pass filter must be less than 10Hz. Therefore, the charging and discharging constant of the capacitor in the RC low-pass filter circuit must satisfy the following: This allows us to select appropriate resistors R and capacitors C.

[0164] The maximum pulse width of all signals in this system Maximum frequency Maximum stimulation current amplitude According to equation (9), the maximum voltage amplitude of the input low-pass filter is... .

[0165] According to the DC component A0 of the pulse signal and its frequency Pulse width Pulse amplitude Relationship and Figure 7 The amplifier gain and the expression for the maximum input voltage of ADC0 are:

[0166] (10)

[0167] It is the maximum voltage amplitude of the input low-pass filter. It is the maximum pulse width. It is the maximum frequency. It is the maximum stimulation current amplitude.

[0168] According to the above formula (10), when the following conditions are met... Under these conditions, select appropriate resistors R5 and R6.

[0169] Similarly, the amplitude of the nth stimulation current The calculation formula is as follows:

[0170] (11)

[0171] In the above formula (11), It is based on the corresponding voltage detected by ADC0 from the channels of the single-pole multi-throw switch (1×N). and The microprocessor sets the parameters, and the microprocessor monitors the amplitude of each stimulation current in real time according to formula (11) to ensure that each stimulation current is within a safe range.

[0172] The design of the electrical stimulation effect detection section includes the design of a signal (voltage) conditioning circuit and a single-pole multi-throw analog switch (1×M). The design of the signal (voltage) conditioning circuit is determined based on the selected vital sign sensor. If the sensor outputs a voltage signal, this signal needs to be conditioned to the sampling range corresponding to ADC1, including differential and amplification processing, similar to... Figure 5 The differential circuit shown and Figure 7 The amplifier circuit shown; if the output signal of the vital signs sensor is a non-voltage signal such as capacitance or current, it needs to be converted to voltage first, then conditioned, and then detected by ADC1; if the vital signs sensor outputs a modular digital signal, it can communicate and detect directly with the module through the microprocessor's I / O port. The design method of the single-pole multi-throw analog switch (1×M) is the same as that of "Selection and Design of Single-Pole Multi-Throw Analog Switch (1×N)".

[0173] The interface design of human-computer interaction devices can be implemented using a traditional LCD touchscreen. Based on the touchscreen's interface protocol, the I / O interface circuit between the touchscreen and the microprocessor is designed. On top of this hardware circuitry, the corresponding human-computer interaction interface is then designed. Alternatively, this part can be implemented using wireless communication, such as Bluetooth or Wi-Fi modules, as the connection channel between the human-computer interaction interface and the microprocessor, enabling remote interaction.

[0174] This invention overcomes the limitations of existing EES systems, such as the lack of ventral targeting in parameter settings and the lack of external intent perception input. It constructs an intelligent, dynamic, and personalized neural stimulation control platform, providing a technological foundation for applications in spinal cord injury, movement disorders, and autonomic nervous system function regulation.

[0175] In addition, the present invention provides the following two application embodiments based on the application:

[0176] Application Example 1:

[0177] This embodiment is equipped with an implantable 64-channel ventral electrode array, combined with the multi-channel closed-loop pulse control system of the present invention, taking a patient with complete spinal cord injury below T10 (AIS-A) as an example.

[0178] This embodiment provides a spinal cord ventral epidural region electrical stimulation neuromodulation system based on a multi-channel electrode array. The system includes an embedded processor, an electrical stimulation current generation module, a current monitoring module, an electrical stimulation effect detection module, and a human-computer interaction module, aiming to restore and regulate the motor and autonomic nerve functions of paralyzed patients. The system uses an STM32 series microprocessor as the core control unit. A configured timer outputs multiple PWM signals with adjustable frequency (10–120Hz), adjustable pulse width (150–500μs), and adjustable amplitude (0.1–10.0mA). After amplitude adjustment by a digital potentiometer, a PFWHMn signal is formed, which is then converted into a current signal with corresponding parameters by a voltage-controlled current source and applied to a 64-channel flexible electrode array implanted in the ventral epidural region of the anterior spinal sulcus of the patient. Through a well-structured combination of sampling resistors and followers, voltage signals are synchronously acquired in each stimulation circuit. A single-pole multi-throw analog switch is used to sequentially multiplex the input low-pass filter and sample the signal via an ADC to achieve real-time monitoring of the electrical stimulation current in each circuit, ensuring safe and stable output. The software presets different movement templates (such as standing, stepping, etc.), each template corresponding to a specific multi-channel combined stimulation mode. The system is connected to external multimodal sensors such as electromyography, body position, and pressure sensors. The sensor signals are processed by the conditioning circuit and then input to the processor's ADC module. The microprocessor analyzes the sensor signals and automatically adjusts the pulse amplitude or firing sequence of the corresponding channel when it detects insufficient muscle response or abnormal body position. In addition, the human-computer interaction part is equipped with an LCD display with touch function and a Bluetooth communication module, which supports doctors to remotely adjust and view parameters. All stimulation and feedback data of the system can be recorded to the memory card in real time for subsequent analysis.

[0179] Application Example 2:

[0180] This embodiment is equipped with an implantable 64-channel ventral electrode array, combined with the multi-channel closed-loop pulse control system of this invention, and externally connected to a multimodal vital signs sensor, taking a patient with complete spinal cord injury below T10 (AIS-A) as an example.

[0181] This embodiment provides a closed-loop spinal cord ventral epidural region electrical stimulation neuromodulation system based on a multi-channel electrode array. The system includes an embedded processor, an electrical stimulation current generation module, a current monitoring module, an electrical stimulation effect detection module, a human-computer interaction module, and a vital sign sensor interface module. It aims to achieve the restoration and regulation of motor and autonomic nerve functions in paralyzed patients while automatically adjusting stimulation parameters based on the patient's real-time biomechanical and electromyographic information. The system uses an STM32 series microprocessor as the core control unit. A configured timer outputs multiple PWM signals with adjustable frequency (10–120Hz), adjustable pulse width (150–500μs), and adjustable amplitude (0.1–10.0mA). After the amplitude is adjusted by a digital potentiometer, a PFWHMn signal is formed, which is then converted into a current signal with corresponding parameters by a voltage-controlled current source and applied to a 64-channel flexible electrode array implanted in the ventral epidural region of the anterior spinal sulcus of the patient's spinal cord. By combining a well-structured sampling resistor with a follower, voltage signals are synchronously acquired in each stimulation circuit. A single-pole multi-throw analog switch is used to sequentially multiplex the input low-pass filter and sample the signal via an ADC, enabling real-time monitoring of the electrical stimulation current in each circuit and ensuring safe and stable output. Simultaneously, several analog front-ends are set up in the electrical stimulation effect detection module to receive signals from joint angle sensors, torque sensors, and surface electromyography electrodes. After amplification, filtering, and rectification, the signals are uniformly input to the processor's multiple ADC channels, providing real-time feedback data for closed-loop control.

[0182] Different motion templates (such as standing, stepping, sitting and standing transitions) are preset in the software. Each template corresponds to a specific multi-channel combined stimulation mode and the desired joint angle trajectory, joint torque and electromyographic recruitment level. External electromyography (EMG) sensors are used to collect surface EMG activity of target muscle groups such as the quadriceps and hamstrings, as well as antagonistic muscle groups. Posture and joint angle sensors are used to measure the motion angles and angular velocities of joints such as the hip, knee, and ankle. Torque sensors or plantar pressure sensors are used to reflect the load and output torque during the support and push-off phases. The above sensor signals are processed by the conditioning circuit and then input to the processor's ADC module. The microprocessor analyzes the sensor signals in real time. When it detects insufficient muscle response, joint angle deviation from the preset trajectory, or output torque below the target threshold, it automatically fine-tunes the pulse amplitude, firing frequency, or firing sequence of the corresponding channel within the current motion template constraint range. For example, it increases the current amplitude of the ventral channel of a specific segment by taking small steps to enhance the recruitment of the iliopsoas or quadriceps, or slightly increases the stimulation frequency during the gait push-off phase to compensate for insufficient joint extension. When abnormal synergy of antagonistic muscles, sudden changes in posture, or abnormal fluctuations in torque or pressure signals are detected, the system immediately reduces the current output of the relevant channel or delays the firing sequence. If necessary, it triggers safety protection logic to suspend stimulation. In addition, the human-computer interaction section is equipped with an LCD display with touch function and a Bluetooth communication module, which supports doctors to remotely adjust and view parameters. All stimulation parameters and multimodal feedback data of the system can be recorded to the memory card in real time for subsequent offline analysis and individualized solution optimization.

[0183] Corresponding to the above system embodiments, this specification also provides embodiments of a neuromodulation method for the ventral epidural region of the spinal cord, which is applied to the aforementioned neuromodulation system for the ventral epidural region of the spinal cord. Figure 8 A flowchart illustrating a neuromodulation method for the ventral epidural region of the spinal cord, as provided in some embodiments of this specification, is shown. Figure 8 As shown, the specific steps include:

[0184] The user interacts with the computer through the human-computer interaction module to perform operations and set parameters.

[0185] N independent pulse currents are generated and applied to the ventral epidural region of the spinal cord through an electrode array;

[0186] The amplitude of the N-channel pulse current is monitored in real time to generate the first feedback signal;

[0187] It detects the body's response to electrical stimulation and generates a second feedback signal;

[0188] Based on the first and second feedback signals, the control parameters used to generate pulse current are adjusted in real time to form a closed-loop control to dynamically optimize the effect of electrical stimulation.

[0189] The first feedback signal, the second feedback signal, and the system status are displayed in real time through the human-computer interaction module.

[0190] The above is a schematic scheme of a neuromodulation method for the ventral epidural region of the spinal cord according to this embodiment. It should be noted that the technical solution of this neuromodulation method for the ventral epidural region of the spinal cord is based on the same concept as the aforementioned neuromodulation system for the ventral epidural region of the spinal cord. Details not described in detail in the technical solution of the neuromodulation method for the ventral epidural region of the spinal cord can be found in the description of the aforementioned neuromodulation system for the ventral epidural region of the spinal cord.

[0191] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0192] The preferred embodiments disclosed above are merely illustrative of this specification. The optional embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this invention. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize this specification. This specification is limited only by the claims and their full scope and equivalents.

[0193] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details described above, which are within the scope of the inventive concept. Various simple modifications can be made to the technical solutions of the present invention. All such simple modifications fall within the protection scope of the present invention.

[0194] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0195] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they are also considered as the content disclosed in the present invention.

Claims

1. A neuromodulation system for the ventral epidural region of the spinal cord, characterized in that, include: Embedded processor; An electrical stimulation current generation module, connected to the embedded processor, is used to generate N independent pulse currents according to the control signal of the embedded processor, where N is an integer greater than or equal to 1; An electrode array, comprising N electrode plates, is connected to the output terminal of the electrical stimulation current generating module for applying the pulsed current to the human body; A real-time current monitoring module, connected to the electrode array and the embedded processor, is used to monitor the amplitude of the pulse current flowing through each electrode in real time and generate a first feedback signal to the embedded processor. An electrical stimulation effect detection module, connected to the embedded processor, is used to detect the body's response signals under electrical stimulation and generate a second feedback signal to the embedded processor. The human-computer interaction module is connected to the embedded processor and is used to display system status information and interact with the user. The embedded processor is configured to: adjust the control signal output to the electrical stimulation current generating module in real time based on the first feedback signal and the second feedback signal to form a closed-loop control system, thereby dynamically adjusting the parameters of the pulse current; The electrical stimulation current generating module includes: N amplitude regulators, whose input terminals respectively receive N fixed-amplitude PWM signals generated by the embedded processor, and whose control terminals receive control signals issued by the embedded processor, are used to output N PFWHMn voltage signals with adjustable frequency, pulse width and amplitude. N voltage-controlled current sources, whose input terminals are respectively connected to the output terminals of the N amplitude regulators, are used to convert the PFWHMn voltage signal into the corresponding pulse current, and the amplitude of the pulse current is not affected by the back-end load. The amplitude regulator includes a digital potentiometer and a first operational amplifier; The digital potentiometer receives the PWM signal and the ground signal at its two ends respectively, and its taps are controlled by the control signal to divide the PWM signal. The first operational amplifier forms a voltage follower, with its input terminal connected to the tap of the digital potentiometer and its output terminal outputting the PFWHMn voltage signal. The voltage-controlled current source includes a sampling resistor, an operational amplifier, and a high-precision instrumentation amplifier, wherein, A gain resistor R is connected between the two inputs of the instrumentation amplifier G ; The output of the instrumentation amplifier is output to the corresponding electrode plate through the sampling resistor. Its non-inverting input receives the PFWHMn voltage signal, and its inverting input is grounded. The output terminal and inverting input terminal of the operational amplifier are both connected to the reference voltage terminal of the instrumentation amplifier, and its non-inverting input terminal is connected to the corresponding electrode plate. The operational amplifier constitutes a voltage follower. wherein the stimulation current In applied to the electrode pad satisfies the following relationship with the voltage signal PFWHMn output by the amplitude adjuster: wherein A G is the voltage gain of the instrumentation amplifier, R AD is the resistance value of the internal resistance of the chip, R G is the resistance value of the gain resistance, R s is the resistance value of the sampling resistance; The voltage-controlled current source includes a first operational amplifier, a second operational amplifier, a transistor, a first resistor, a second resistor, and a sampling resistor, wherein... The output terminal of the first operational amplifier is connected to the base of the transistor, its non-inverting input terminal receives the PFWHMn voltage signal, and its inverting input terminal is connected to the output terminal of the second operational amplifier. The non-inverting input of the second operational amplifier is connected to the emitter of the transistor, and its inverting input is connected to the inverting input of the first operational amplifier via a first resistor and grounded via a second resistor. The first operational amplifier and the second operational amplifier constitute a deep negative feedback circuit; The collector of the transistor is connected to the corresponding electrode plate, and its emitter is grounded through the sampling resistor. wherein the stimulation current In applied to the electrode pad satisfies the following relationship with the voltage signal PFWHMn output by the amplitude adjuster: wherein Is is the current flowing through the sampling resistor Rs, R1 and R2 are the resistance values of the first and second resistors, respectively, and R s is the resistance value of the sampling resistor.

2. The system of claim 1, wherein, The real-time current monitoring module includes: N voltage sampling and follower units, each unit is used to acquire the voltage across the sampling resistor in the corresponding electrode circuit and output a voltage pulse signal proportional to the pulse current; A single-pole multi-throw analog switch has multiple input terminals connected to the output terminals of the N voltage sampling and follower units, and its control terminal is controlled by the embedded processor to sequentially select the voltage pulse signals. A low-pass filter, connected to the output of the single-pole multi-throw analog switch, is used to extract the DC component of the selected voltage pulse signal. The embedded processor is connected to the output of the low-pass filter and is configured to calculate the amplitude of the pulse current based on the DC component and the known frequency and pulse width of the corresponding pulse current.

3. The system of claim 2, wherein, The low-pass filter includes a first capacitor, a second capacitor, a sixth operational amplifier, a fourth resistor, a fifth resistor, and a sixth resistor, wherein... The first terminal of the first capacitor and the first terminal of the second capacitor are respectively connected to the two ends of the fourth resistor, and the second terminals of the first capacitor and the second terminals of the second capacitor are grounded. The first end of the fourth resistor is connected to the output end of the single-pole multi-throw analog switch, and its second end is connected to the non-inverting input end of the sixth operational amplifier. The inverting input of the sixth operational amplifier is grounded via the fifth resistor on one hand, and connected to its output via the sixth resistor on the other hand. Its output is connected to the ADC in the embedded processor.

4. The system of claim 1, wherein, The electrical stimulation effect detection module includes: At least one vital sign sensor is used to detect the physical response of the human body to electrical stimulation; A signal conditioning circuit, connected to the vital signs sensor, is used to condition the signal output by the vital signs sensor to the sampling range of the analog-to-digital converter of the embedded processor. A single-pole multi-throw analog switch has multiple input terminals connected to the output terminals of one or more of the signal conditioning circuits, and its control terminal is controlled by the embedded processor to sequentially select the conditioned vital signs.

5. The system of claim 1, wherein, The embedded processor is specifically used for: The human-computer interaction module receives the target stimulus parameters and / or safety thresholds set by the user. The current amplitude fed back by the real-time current monitoring module is compared with the safety threshold. If it exceeds the range, an alarm is triggered or the output is automatically cut off. The body response signal fed back by the electrical stimulation effect detection module is compared with the expected effect, and at least one parameter of the frequency, pulse width and amplitude of the pulse current is automatically adjusted based on a preset control algorithm so that the body response signal approaches the expected effect.

6. A method for neuromodulation of the ventral epidural region of the spinal cord, comprising, The method, applied to the neuromodulation system for the ventral epidural region of the spinal cord as described in any one of claims 1-5, comprises: The user interacts with the computer through the human-computer interaction module to perform operations and set parameters. N independent pulse currents are generated and applied to the ventral epidural region of the spinal cord through an electrode array; The amplitude of the N pulse currents is monitored in real time to generate a first feedback signal; It detects the body's response to electrical stimulation and generates a second feedback signal; Based on the first feedback signal and the second feedback signal, the control parameters used to generate the pulse current are adjusted in real time to form a closed-loop control to dynamically optimize the electrical stimulation effect. The human-computer interaction module displays the first feedback signal, the second feedback signal, and the system status in real time.

Images