A wearable transdermal electrical stimulation device and control method thereof

Abstract

The application provides a wearable transdermal electrical stimulation device and a control method thereof, the wearable transdermal electrical stimulation device comprising an electrode assembly, a stimulation signal generation and output module, a monitoring and feedback module, a power management module, a core control and processing unit and a user interface, each component works cooperatively through electrical connection, through constant current output control, multi-mode stimulation adjustment, multi-waveform drive generation, intelligent electrode contact monitoring, long-term burn risk prediction and safety protection mechanism, etc., the long-term burn risk prediction mechanism can construct a heat accumulation and risk evaluation model through real-time sampling of current and impedance changes, monitor and manage the heat load of the skin without adding new hardware, and prevent the occurrence of chronic burn risk, and the wearable transdermal electrical stimulation device can significantly improve the safety, stability and comfort of the existing electrical stimulation technology in multiple aspects.

Description

Technical Field

[0001] This invention relates to the field of biomedical electronics technology, and in particular to a wearable transcutaneous electrical stimulation device and its control method. Background Technology

[0002] In recent years, transcutaneous electrical acupoint stimulation (TEAS), as a non-invasive method that integrates traditional meridian theory with modern electrophysiological technology, has shown significant advantages in regulating physiological balance and relieving exercise discomfort. This technology effectively regulates the autonomic nervous system by stimulating acupoints on the wrist (such as Neiguan acupoint) with pulsed currents of specific parameters, without the side effects of drugs.

[0003] However, existing electrical stimulation devices have limited parameter adjustment ranges, simple waveforms, and lack sophisticated electrode contact monitoring mechanisms. Current devices primarily focus on transient overcurrent protection, neglecting the potential for heat buildup on the skin during prolonged use, i.e., the risk of chronic burns. Because Joule heating occurs when current passes through the electrode interface, even if the transient current is within a safe range during prolonged continuous stimulation, the lack of effective thermal management and energy monitoring can still lead to low-temperature thermal damage to skin tissue, i.e., chronic burns.

[0004] Currently, the market lacks intelligent terminals capable of real-time assessment of skin thermal load and predictive safety protection based on electrode contact status. Therefore, developing an intelligent wearable transdermal acupoint electrical stimulation device with high-precision constant current drive, multi-mode acupoint adjustment, and long-term burn risk assessment capabilities has significant engineering application value for improving the safety and comfort of autonomic nervous system regulation through electrical stimulation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a wearable transcutaneous electrical stimulation device.

[0006] Another technical problem to be solved by the present invention is to provide a control method for the above-mentioned wearable transcutaneous electrical stimulation device.

[0007] The technical solution adopted in this invention is: A wearable transcutaneous electrical stimulation (TES) device includes an electrode assembly, a stimulation signal generation and output module, a monitoring and feedback module, a power management module, a core control and processing unit, and a user interface. These components work together via electrical connections. The electrode assembly includes a flexible raised substrate and a radial gradient impedance structure. The flexible raised substrate, serving as the electrode body, is integrally molded from a conductive rubber material (composed of conductive nanomaterials and elastomer polymers). Its contact surface is designed as a convex elongated elliptical structure, which exhibits significant flexibility. Under wearing pressure, the surface of the elongated elliptical can generate adaptive elastic contact deformation. Through a physical collapse effect, it transforms from initial point / line contact to surface contact, ultimately achieving conformal contact with human tissue and significantly reducing contact impedance. To eliminate the stinging sensation caused by charge accumulation at the electrode edges, the radial gradient impedance structure controls the distribution concentration of conductive nanomaterials within the flexible raised substrate, making it radially decreasing from the center to the edge. This process creates an impedance gradient on the electrode contact surface that radially increases from the center to the edge, forcing the current to converge towards the central region of the raised structure, thereby balancing the current density across the entire contact interface and effectively preventing localized heat accumulation. The stimulation signal generation and output module includes an electrical stimulation driver chip, a two-stage conversion output circuit, and a high-efficiency boost circuit. The two-stage conversion output circuit generates symmetrical bidirectional pulse electrical stimulation signals, achieving efficient and stable electrical stimulation output. The high-efficiency boost circuit can boost the battery voltage to the required high voltage. Combined with the main control circuit, the electrical stimulation driver chip uses a point-plotting method to achieve multi-mode output, enabling different combinations of square waves and sine waves within a wide frequency range of 1-100Hz to meet the stimulation needs of different users. It achieves smooth waveform transitions, avoiding potential pricking sensations during stimulation and providing a more natural neural stimulation method. The monitoring and feedback module, composed of an embedded sensor and a high-precision analog-to-digital converter (ADC) module, is used to monitor the impedance between the electrode and the skin in real time. The system continuously collects skin impedance and impedance change rate data to ensure that the electrode contact with the skin is always under optimal conditions. Once poor electrode contact is detected and the impedance change rate exceeds a preset threshold, the monitoring and feedback module automatically activates the automatic adjustment mechanism. The system adjusts the intensity and frequency of the output current to avoid overstimulation or heat accumulation caused by uneven current. The monitoring and feedback module is closely integrated with the heat accumulation model to jointly monitor and prevent long-term burn risks. Its core function is to ensure that the device always operates under safe and effective conditions. The power management module uses a rechargeable lithium battery with a charging interface. The power management module has battery charging and overvoltage protection functions to ensure safe battery use. The built-in low-power management logic module can automatically enter sleep mode or reduce power consumption according to the user's operation status, effectively extending the device's battery life. The aforementioned low-power management logic module can ensure a continuous working time of no less than 8 hours without affecting the core stimulation function, meeting the user's needs for long-term wear and use. The core control and processing unit consists of a microprocessor and an edge computing and intelligent algorithm module integrated internally or externally. The microprocessor is a low-power processor responsible for real-time processing and analysis of data from various sensors and controlling the electrical stimulation output. The edge computing and intelligent algorithm module is responsible for executing real-time decisions and adaptive control. Based on real-time data, the module will automatically adjust the current output intensity, stimulation mode, or heat management strategy to ensure the safe and stable operation of the system. The microprocessor and the edge computing and intelligent algorithm module are the core control unit (core control and processing unit) of this system, responsible for real-time data processing, intelligent algorithm execution, and coordination with other hardware modules. The design of this module aims to achieve efficient data processing, low-latency control response, and intelligent adaptive capabilities of the device. The user interface includes control buttons, stimulation indicator lights, and Bluetooth communication, enabling bidirectional signal transmission with the core control and processing unit.

[0008] Preferably, in the above-mentioned wearable transcutaneous electrical stimulation device, the electrode assembly is a pair (two) elastic composite dry electrodes, the electrodes are convex elongated elliptical raised structures, and the working surface of the electrodes is processed into a concave cylindrical shape; the electrode substrate is made of medical-grade thermoplastic elastomer (such as TPU, SEBS), and its interior is uniformly dispersed with a mixture of metal conductive particles (such as nano silver powder, micron-sized nickel powder) and one-dimensional conductive nanofibers (such as carbon nanotubes), which are mixed by gradient infusion.

[0009] Preferably, in the above-mentioned wearable transdermal electrostimulation device, the elastic composite dry electrode is obtained through multilayer screen printing or gradient perfusion process, and different concentrations of metal conductive particles (preferably spherical silver powder or flake silver powder) are filled in different radial regions of the raised electrode: in the central region of the top crown of the electrode (central conductive region), the filling amount of metal particles is higher than its percolation threshold (e.g., mass fraction of 60%-80%), and the particles form a tight mutual contact, exhibiting low impedance characteristics, serving as the main conduction channel for current; in the radial region extending from the center to the edge (edge ​​high-resistance region), the distribution density of metal particles is gradually reduced, increasing the polymer gap between particles. This controlled particle distribution gradient makes the impedance of the electrode edge region relatively high, thereby forcing the current to converge towards the center of the raised structure, forming a gradient impedance distribution.

[0010] The design of each hardware module in the aforementioned wearable transcutaneous electrical stimulation device ensures the stability, comfort, and safety of the device.

[0011] Preferably, the aforementioned wearable transcutaneous electrical stimulation device incorporates constant current control algorithm, stimulation mode control algorithm, long-term burn risk detection algorithm, electrode contact dynamic monitoring algorithm, and personalized stimulation adjustment algorithm as key technologies. The modules executing each algorithm are as follows: The constant current control algorithm consists of a core control and processing unit (logic operation) and a monitoring and feedback module (current sampling feedback). The stimulation mode control algorithm consists of a core control and processing unit and a stimulation signal generation and output module. The long-term burn risk detection algorithm consists of a core control and processing unit (edge ​​computing) and a monitoring and feedback module (providing impedance / ambient temperature). The electrode contact dynamic monitoring algorithm includes a monitoring and feedback module (acquiring impedance change rate). dZ / dt ); The personalized stimulus adjustment algorithm: core control and processing unit (storage and recall of historical models). These algorithms, through real-time calculations by the core control and processing unit, enable precise adjustment of parameters such as current, voltage, and stimulation mode to ensure the efficiency and safety of the equipment.

[0012] Preferably, the above-mentioned wearable transcutaneous electrical stimulation device involves the following algorithm: 1) Constant current control algorithm The core of the constant current control algorithm is to adjust the output current through real-time sampling feedback to ensure that it always remains within the set range. Specifically, the system first collects current data through a precise current sampling resistor and transmits it to the intelligent control unit. The core control and processing unit executes impedance-adaptive level switching logic to compare the deviation between the sampled current and the preset target value using the plotting method in real time. Based on the feedback of the load impedance state, the system dynamically matches the optimal driving voltage from multiple preset boost levels to adapt to the dynamic changes in skin impedance and ensure current stability. Under good electrode contact, current fluctuations are always controlled within ±10% of the target current. 2) Stimulus mode control algorithm The system utilizes multiple stimulation modes and combines them with waveform generation algorithms to achieve smooth switching between stimulation modes. The system selects low-frequency, high-frequency, or dual-frequency alternating modes according to user needs and supports multiple waveforms such as sine waves and square waves. When switching waveforms, a transition algorithm is used to avoid generating uncomfortable stimulation through smooth gradient changes, ensuring a smooth and seamless transition between different modes. 3) Security protection mechanism To ensure the safety and comfort of the device, this invention designs a safety protection system with real-time risk monitoring, graded safety response, predictive stimulation management, and automatic recovery mechanism. This system monitors the contact quality between the electrode and the skin, the output current, and the electrode's operating status in real time, automatically adjusts stimulation parameters, and responds promptly to any abnormalities, preventing skin damage and discomfort caused by poor contact or overstimulation. Four sub-modules (real-time risk monitoring, graded safety response, predictive stimulation management, and automatic recovery mechanism) work collaboratively to ensure the safety and effectiveness of the device during use. Through real-time data acquisition and intelligent analysis, the system can dynamically adjust stimulation parameters to minimize burns and discomfort caused by poor electrode contact or overstimulation. 4) Algorithm for detecting long-term burn risk This algorithm does not require a temperature sensor. It relies on existing data such as current, electrode area, and skin impedance to indirectly calculate the heat accumulation and dissipation status of the skin, and assess the risk of burns in real time. The algorithm combines current feedback, changes in skin impedance, and the dynamic balance between heat generation and dissipation, which can effectively avoid burns caused by prolonged current stimulation. 5) Electrode contact dynamic monitoring algorithm Real-time monitoring of electrode contact quality is dynamically assessed through impedance change rate (dZ / dt) and current deviation (ΔI(t)). By collecting skin impedance and current feedback, the intelligent control unit can calculate the electrode contact status and predict possible poor contact or electrode slippage. When electrode contact is poor, the system will automatically reduce current output to avoid uncomfortable stimulation. 6) Personalized stimulus adjustment algorithm Based on the stimulus requirements input by the user, the system automatically selects low-frequency, high-frequency, or dual-frequency alternating modes according to preset rules, and executes a waveform transition algorithm when switching modes; it includes a user stimulus preference learning step, which generates a personalized stimulus parameter model by recording the user's modulation intensity, mode, and pulse width data.

[0013] Preferably, in the above-mentioned wearable transdermal electrical stimulation device, the long-term burn risk detection algorithm is as follows: 1) Calculation of instantaneous heat generation power density The core processor obtains real-time current based on the current sampling circuit. Electrode-skin impedance and the effective contact area determined by the electrode physical parameters Calculate the instantaneous heat generation power density : (1) 2) Dynamic heat dissipation estimation The system uses Newton's law of cooling to simulate the energy dissipation of skin to the environment. : (2) in, The thermal conductivity coefficient, This is the estimated temperature for the previous cycle. The ambient temperature (measured by the thermistor built into the wristband or set to a preset constant value). 3) Recursive Iterative Algorithm for Skin Temperature The skin temperature is estimated in real time using the following discretized iterative formula. : (3) in For total heat production power, For heat conversion efficiency, and These represent the average specific heat capacity and the affected mass of the skin tissue, respectively. 4) Comprehensive Risk Assessment Function

[0014] (4) in, These are weighting coefficients, which can be adjusted based on experimental data; It is the safe threshold temperature. Set the current value; 5) Tiered response strategy and automatic recovery Intelligent control unit according to The real-time values ​​are processed using the following tiered security logic: Level 1 warning stage ( ): The system determines that there is a risk of long-term cumulative burns; at this time, the stimulation is not interrupted, but the "heat restriction mode" is entered, which slows down heat generation by linearly reducing the pulse width or current intensity (e.g., reducing by 5% per cycle) until the risk value drops; Secondary blocking stage ( If the system determines that there is an immediate risk of damage or serious hardware failure, it will immediately cut off the output of the drive circuit, lock the device, and send an alarm signal to the user via indicator lights. Intelligent recovery mechanism: When the risk value falls back to the safe range and the impedance... Once the system stabilizes, it will use a slow start approach to gradually restore the parameters to the user's initial settings, ensuring the continuity and comfort of the stimulation.

[0015] The control method for the aforementioned wearable transcutaneous electrical stimulation device comprises the following specific steps: (1) System initialization and self-test: After receiving the wake-up signal, the power management module starts the low-power microprocessor and calls the user's historical preference model or default parameters from its non-volatile memory to complete the automatic loading of parameters; at the same time, the system executes the power-on self-test program to scan the battery voltage and circuit integrity. (2) Wearing detection and mode selection: The monitoring and feedback module sends a weak detection signal to the skin, measures the impedance value of the electrode-skin interface in real time, and judges that the contact state is good. Then the system enters the mode setting stage and automatically configures the stimulation mode (low frequency, high frequency or dual frequency alternation) and target current intensity according to the user's key input or preset rules. (3) Stimulation output and constant current control: The stimulation signal generation and output module drives the bipolar conversion circuit to output a symmetrical bidirectional pulse signal to eliminate net DC bias and prevent skin electrolysis; at the same time, the current sampling circuit collects the voltage signal on the sampling resistor in real time, converts it into the actual output current value and real-time load impedance data and feeds it back to the microprocessor; the microprocessor executes the constant current control algorithm based on the feedback data, dynamically adjusts the driving voltage or pulse width, and ensures that the actual current is always stable within ±10% of the target value; (4) Estimating subcutaneous heat accumulation and preventing low-temperature burns: In the parallel long-term burn risk modeling process, the core control and processing unit calculates the instantaneous output power in real time based on the collected current, voltage and impedance data, and constructs a skin heat load model to estimate the subcutaneous heat accumulation. This model combines the heat growth rate and current deviation to calculate the comprehensive risk assessment value. Once the risk value is detected to exceed the preset threshold or there is an electrode slippage trend, the system immediately triggers a graded safety response and automatically performs degraded output or shut-off protection. (5) End and hibernation: The microprocessor monitors the timer status, button operation and wearing status in real time; when it detects that the stimulation has ended, the user has turned off the device or has not worn it for a long time, the system automatically saves the effective parameters of this operation (such as intensity and mode) to the memory to update the personalized model, then cuts off the power supply to the peripheral device and enters the microampere-level low power hibernation mode, and waits for the next system wake-up.

[0016] The beneficial effects of this invention are: The aforementioned wearable transdermal electrical stimulation device uses an electrode assembly made of one-piece molded flexible conductive rubber. The contact surface has a convex elongated elliptical structure. Utilizing the high flexibility of the material, the electrode undergoes adaptive elastic contact deformation under wearing pressure, achieving conformal contact with the skin. At the same time, the electrode has a gradient impedance structure inside, eliminating the stinging sensation caused by edge effects. The device incorporates a long-term heat accumulation model based on energy conservation. By monitoring the current, impedance, and effective contact area of ​​the electrode in real time, it indirectly calculates the skin's heat load and temperature rise. The main control processor executes a graded safety response strategy based on a comprehensive risk index, effectively controlling safety.

[0017] The wearable transdermal electrical stimulation device provides a stable, efficient, and safe experience during long-term use through constant current output control, multi-mode stimulation adjustment, multi-waveform drive generation, intelligent electrode contact monitoring, long-term burn risk prediction, and safety protection mechanisms. The device overcomes the influence of skin impedance changes through constant current control technology, ensuring a stable stimulation current under different skin conditions. It also supports multi-mode stimulation adjustment, achieving wide frequency, wide pulse width, peak current adjustment, and various waveform outputs (such as biphasic square waves and sine waves). Combined with a smooth mode switching mechanism, it effectively improves comfort and neuroadaptability.

[0018] Furthermore, the wearable transdermal electrical stimulation device integrates intelligent electrode contact monitoring. By monitoring skin impedance and its changes in real time, it automatically determines whether the electrode contact is good and adjusts the stimulation output according to electrode slippage or detachment, effectively preventing overstimulation or discomfort caused by poor contact. Simultaneously, the device has a long-term burn risk prediction mechanism. By sampling current and impedance changes in real time, it constructs a heat accumulation and risk assessment model, monitoring and managing skin heat load without the need for additional hardware, thus preventing the risk of chronic burns. The device also features low-power management and a user-friendly interface design. Functions such as one-click mode switching, intensity adjustment, and parameter memory allow users to operate the device easily without professional knowledge, enhancing the user experience.

[0019] As an intelligent electrical stimulation device integrating monitoring and feedback modules, real-time risk monitoring, intelligent graded safety response, predictive stimulation management, and automatic recovery mechanisms, the wearable transcutaneous electrical stimulation device can significantly improve the safety, stability, and comfort of existing electrical stimulation technologies in several aspects: 1) Improve safety and prevent overstimulation and burns. By monitoring the contact quality between the electrodes and the skin in real time, the monitoring and feedback module can accurately determine whether the electrodes are making good contact with the skin. When the electrode contact is poor, the system can automatically reduce the output current or adjust the stimulation parameters, thereby effectively avoiding overstimulation or heat accumulation and preventing burns caused by local overheating. By calculating real-time risk assessment values, the system can determine the current working status and ensure that the equipment always operates within a safe range.

[0020] 2) Improve comfort and reduce discomfort Through morphological optimization and materials science design of the electrode components, the user's comfort during prolonged wear is significantly improved. Adaptive conformal contact reduces localized pressure: Unlike traditional rigid electrodes, this invention uses highly flexible conductive rubber to fabricate raised, elongated elliptical electrodes. Under wearing pressure, the electrodes can undergo adaptive elastic deformation. A gradient impedance structure effectively solves the stinging sensation caused by charge accumulation on the dry electrode contact surface, achieving low-impedance, highly comfortable physical pressure contact without the need for conductive paste. This significantly improves wearing comfort and eliminates skin irritation.

[0021] 3) High precision and stability of stimulus output To address the issue of unstable stimulation intensity caused by dynamic changes in skin impedance, a current sampling circuit in the monitoring and feedback module, combined with a constant current control algorithm, ensures that output current fluctuations are controlled within ±10% of the target value. Even when the user sweats or exercises, causing drastic fluctuations in contact impedance, a stable acupoint stimulation intensity can still be maintained, ensuring the clinical effectiveness of autonomic nervous system modulation.

[0022] 4) Improve system reliability and durability Because the monitoring and feedback module can monitor electrode contact quality, heat accumulation, and current output in real time, the equipment can adjust its operating status promptly in case of poor contact or excessive heat, preventing overwork or damage. This mechanism effectively avoids malfunctions caused by electrode aging, damage, or prolonged use, thereby improving the system's reliability and durability.

[0023] 5) Enhance intelligence and flexibility Through edge computing and real-time data processing, devices can perform complex data analysis and decision-making locally. This highly integrated edge computing capability allows devices to operate independently of cloud computing, resulting in lower latency, faster response times, and avoiding network dependency issues. Furthermore, through remote upgrades and data synchronization, devices can continuously optimize and adapt to new usage requirements. Attached Figure Description

[0024] Figure 1 This is a schematic block diagram of the hardware components of the wearable transcutaneous electrical stimulation device described in this invention; Figure 2 This is a schematic diagram of the wearable transcutaneous electrical stimulation device of the present invention. In the figure: 1-wristband body, 2-outer shell, 3-electrode assembly, 4-strap; Figure 3 This is a schematic diagram illustrating the impedance measurement principle of the wearable transcutaneous electrical stimulation device described in this invention. Figure 4 This is a flowchart of the algorithm for the long-term burn mechanism of the wearable transcutaneous electrical stimulation device described in this invention. Figure 5This is a schematic diagram of the control process of the wearable transcutaneous electrical stimulation device described in this invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1 like Figure 1-5 As shown, the wearable transcutaneous electrical stimulation device is a wristband-type transcutaneous intelligent electrical stimulation device used for autonomic nervous system regulation. It regulates the autonomic nervous system by stimulating the Neiguan acupoint with electrodes. Its specific hardware configuration, working principle, and implementation steps are as follows: 1. Hardware Configuration like Figure 1 As shown, this wearable transcutaneous electrical stimulation device for autonomic nervous system modulation mainly consists of six parts: a core control and processing unit, a power management module, a stimulation signal generation and output module, a monitoring and feedback module, an electrode assembly, and a user interface. These modules work together through electrical connections to achieve constant current closed-loop control and intelligent safety protection.

[0027] 1) Core Control and Processing Unit This unit serves as the computing center of the entire system, employing an ARM Cortex-M7 low-power microprocessor (MCU) as the main control chip. It integrates or connects external edge computing and intelligent algorithm modules. This unit is responsible for receiving real-time feedback data from the monitoring module, running constant current control algorithms, long-term burn risk detection models, and predictive stimulation management logic. Based on real-time analysis results (such as risk prediction), it sends control commands to the stimulation drive circuit and simultaneously provides feedback on the device status through a user interface. This user interface includes control buttons, stimulation indicator lights, and Bluetooth communication, enabling bidirectional signal transmission with the core control and processing unit.

[0028] 2) Power Management Module This module is responsible for providing stable power to all parts of the system and managing the overall power consumption. It uses a rechargeable lithium battery as the core power source and is equipped with charging management and protection circuits to prevent overcharging, over-discharging, or short circuits, ensuring safe use. It also has a built-in low-power management logic module that automatically cuts off power to unnecessary circuits when not in operation.

[0029] 3) Stimulus signal generation and output module This module uses the NNC6121 chip (electrostimulation driver chip) to convert digital control commands into physical stimulation pulses that act on the human body. A two-stage conversion output circuit generates symmetrical bidirectional pulsed electrostimulation signals, achieving efficient and stable electrostimulation output. A high-efficiency boost circuit receives system power and boosts the lithium battery voltage to the high compliance voltage required for driving. Parameter adjustment capability: Supports wide-range parameter output, including continuously adjustable frequency (1-100Hz), pulse width (200-500μs), and current (1-50mA). Multi-mode support: The hardware circuit supports software-defined generation of various waveforms such as sine waves and square waves, and can perform low-frequency, high-frequency, or dual-frequency alternating mode switching.

[0030] 4) Electrode assembly It should be noted that the specific dimensions given in this embodiment are the optimal values ​​to fit the anatomical features of the inner wrist of most adult users.

[0031] like Figure 2 As shown, the main body 1 of the bracelet adopts a flat, rounded rectangular design, and its outer shell 2 is 30mm × 40mm in size. The 40mm axis is parallel to the wrapping direction of the strap 4, and the 30mm axis is parallel to the length direction of the user's arm.

[0032] Based on the aforementioned shell configuration, specific three-dimensional dimensional design and spatial layout optimization were performed on electrode assembly 3 to facilitate the implementation of the aforementioned long-term burn risk monitoring algorithm: In this embodiment, the electrode assembly serves as the direct terminal for current output, and the electrode assembly is preferably a pair (two) of elastic composite dry electrodes respectively arranged on the inner side of the wrist.

[0033] ① Electrode geometry and spatial layout: The electrode assembly is preferably a pair (two) of elastic composite dry electrodes arranged on the inner side of the bracelet body, including a first electrode and a second electrode. The two electrodes are arranged in parallel along the 30mm axis of the bracelet body (i.e., parallel to the arm length direction).

[0034] Each electrode is presented as a protruding, elongated elliptical ridge, with its geometric major axis extending along the 40mm axis of the bracelet body (i.e., parallel to the direction of the strap's wrapping). Specific preferred dimensional parameters are as follows: Bottom dimensions: The length of the major axis of the bottom of a single electrode ranges from 25 mm to 28 mm (preferably 26 mm), and the width of the minor axis ranges from 8 mm to 12 mm (preferably 10 mm).

[0035] The height of the protrusion is 2mm to 4mm (preferably 3mm) at the center of the electrode relative to the bottom of the inner surface of the bracelet, forming a gentle arc-shaped crown.

[0036] Spacing design: The center longitudinal gap (along the arm) between the two electrodes is set to 12mm to 15mm. This protruding elongated elliptical design ensures that the electrodes can accurately contact and compress the target subcutaneous tissue area.

[0037] ② Composite material preparation and elastic conformal maintenance: The electrode substrate is made of medical-grade thermoplastic elastomer, which contains a uniformly dispersed mixture of conductive metal particles (such as nano-silver powder and micron-sized nickel powder) and one-dimensional conductive nanofibers (such as carbon nanotubes). This particle-fiber hybrid network structure ensures the conductivity stability of the electrode under large strain cycles while maintaining extremely low bulk resistivity.

[0038] ③ Gradient impedance distribution achieves edge protection: To prevent low-temperature burns caused by excessive current density at the electrode edges, this embodiment uses multi-layer screen printing or gradient infusion processes to fill different radial regions of the raised electrode with conductive metal particles (preferably spherical or flake-shaped silver powder). The specific design is as follows: Central conductive region: In the central region of the top crown of the electrode, the filling amount of metal particles is higher than its percolation threshold (e.g., mass fraction of 60%-80%), and the particles form a tight mutual contact, exhibiting low impedance characteristics, and serving as the main conduction channel for current.

[0039] High-resistivity edge region: In the radial region extending from the center to the edge, the distribution density of metal particles gradually decreases, increasing the polymer gaps between the particles. This controlled particle distribution gradient results in relatively high impedance in the electrode edge region, thereby forcing current to converge towards the center of the raised structure.

[0040] 5) Monitoring and Feedback Module The electrode-skin impedance is achieved using a preferred AD5933 12-bit, 1MSPS impedance converter. For example... Figure 3 The impedance measurement schematic shown illustrates how the AD5933 generates a programmable excitation voltage (0.1-5V) and measures the real and imaginary parts of the electrode-skin complex impedance in single-point mode. The impedance amplitude is then calculated in the MCU, and the impedance range is programmatically adjusted using a digital potentiometer MCP4017. This impedance value serves as the equivalent skin resistance in the subsequent heat accumulation model. Additionally, an ambient temperature thermistor (NTC-Env) is placed in the device's vent or near the wristband but not in contact with the skin to measure the ambient air temperature. Both use the same voltage divider circuit, differing only in the ADC channel, while maintaining a consistent sampling frequency (around 10Hz). The impact on power consumption is negligible, thus explicitly incorporating the heat dissipation process from the skin into the heat accumulation model, resulting in a more realistic assessment of the heat load.

[0041] 2. Algorithm Design The algorithm for detecting long-term burn risk is illustrated in the following flowchart: Figure 4 As shown: This long-term burn risk detection algorithm eliminates the need for skin contact temperature sensors. Utilizing existing data such as current, electrode area, and skin impedance, along with a simple thermistor placed in the device's vent, it indirectly calculates the skin's heat accumulation and dissipation status to assess the risk of burns in real time. By combining current feedback, changes in skin impedance, and the dynamic balance between heat generation and dissipation, the algorithm effectively prevents burns caused by prolonged electrical stimulation.

[0042] To accurately estimate the heat load on the skin, a heat accumulation model was first constructed, taking into account the effects of factors such as current, skin impedance, and skin area.

[0043] 1) Calculation of instantaneous heat generation power density First, the core processor obtains the real-time current based on the current sampling circuit. Electrode-skin impedance and the effective contact area determined by the electrode physical parameters Calculate the instantaneous heat generation power density : (1) 2) Dynamic heat dissipation estimation The system uses Newton's law of cooling to simulate the energy dissipation of skin to the environment. : (2) in, The thermal conductivity coefficient, This is the estimated temperature for the previous cycle. The ambient temperature (measured by the built-in thermistor of the wristband or set to a preset constant value).

[0044] 3) Recursive Iterative Algorithm for Skin Temperature Based on the law of conservation of energy, the system uses the following discretized iterative formula to track and estimate skin temperature in real time. : (3) in For total heat production power, For heat conversion efficiency, and These represent the average specific heat capacity of skin tissue and the mass affected, respectively.

[0045] 4) Comprehensive Risk Assessment Function

[0046] To achieve multi-dimensional security assessment, the system constructs a comprehensive risk index, the mathematical expression of which is: (4) This function consists of the following three key items: Temperature exceeding the limit: This reflects the deviation of the current temperature from the safe threshold and is the core basis for preventing low-temperature burns; Temperature rise rate term: The derivative of temperature change is used to detect the risk of instantaneous thermal surges caused by electrode slippage and a sharp reduction in contact area; Runaway energy integral term: By integrating the square of the current deviation through a sliding window, the stability of the hardware constant current closed loop is monitored. Even if the temperature rise is not yet significant, if the current fluctuates continuously, this term can quickly raise the risk value, providing redundancy protection.

[0047] in These are weighting coefficients, which can be adjusted based on experimental data; It is the safe threshold temperature. Set the current value.

[0048] 5) Tiered response strategy and automatic recovery Intelligent control unit according to The real-time values ​​are processed using the following tiered security logic: Level 1 warning stage ( The system determines that there is a risk of long-term cumulative burns. At this time, the stimulation is not interrupted, but the system enters "heat restriction mode" to slow down heat generation by linearly reducing the pulse width or current intensity (e.g., by 5% per cycle) until the risk value drops.

[0049] Secondary blocking stage ( If the system determines there is an immediate risk of damage or serious hardware failure, it will immediately cut off the drive circuit output, lock the device, and send an alarm signal to the user via indicator lights.

[0050] Intelligent recovery mechanism: When the risk value falls back to the safe range and the impedance... Once the system stabilizes, it will use a slow start approach to gradually restore the parameters to the user's initial settings, ensuring the continuity and comfort of the stimulation.

[0051] 3. Main Control Flow like Figure 5 As shown, the electrical stimulation control method in this embodiment includes a complete closed-loop logic from system wake-up, wear detection, constant current output to safe shutdown. The specific steps are as follows: During the S01 system initialization and self-test phase, the power management module starts the low-power microprocessor upon receiving the wake-up signal and retrieves the user's historical preference model or default parameters from its non-volatile memory to automatically load the parameters. Simultaneously, the system executes a power-on self-test program to scan the battery voltage and circuit integrity, ensuring that the compliant voltage estimation and safe startup current calculation are accurate, providing a safety benchmark for subsequent operation.

[0052] During the S02 wearing detection and mode selection phase, the monitoring and feedback module sends a weak detection signal to the skin and measures the impedance value of the electrode-skin interface in real time to determine the contact status. If the impedance is within the effective range, it indicates that the wearing is good, and the system then enters the mode setting phase. The intelligent control unit automatically configures the stimulation mode (low frequency, high frequency, or dual frequency alternation) and target current intensity according to the user's key input or preset rules, completing the preparation before output.

[0053] During the S03 stimulation output and constant current control stage, the stimulation signal generation and output module drives the bipolar converter circuit to output symmetrical bidirectional pulse signals to eliminate net DC bias and prevent skin electrolysis. Simultaneously, the current sampling circuit acquires the voltage signal across the sampling resistor in real time, converting it into the actual output current value and real-time load impedance data, which are then fed back to the microprocessor. Based on the feedback data, the microprocessor executes a constant current control algorithm, dynamically adjusting the drive voltage or pulse width to ensure that the actual current remains stable within ±10% of the target value.

[0054] During the parallel execution of long-term burn risk modeling S04, the intelligent algorithm module calculates the instantaneous output power in real time based on the collected current, voltage, and impedance data, and constructs a skin heat load model to estimate the subcutaneous heat accumulation. This model combines the heat growth rate and current deviation to calculate a comprehensive risk assessment value. Once the risk value is detected to exceed the preset threshold or there is a tendency for electrode slippage, the system immediately triggers a graded safety response, automatically executing degraded output or shutting down protection, thereby effectively preventing low-temperature burns.

[0055] During the S05 end and sleep phases, the microprocessor monitors the timer status, button operations, and wearing status in real time. When it detects that the stimulation has ended, the user has turned off the device, or the device has not been worn for an extended period, the system automatically saves the valid parameters of this operation (such as intensity and mode) to memory to update the personalized model. It then cuts off power to the peripherals and enters a microampere-level low-power sleep mode to maximize device battery life, awaiting the next system wake-up.

[0056] The aforementioned wearable transcutaneous electrical stimulation device combines traditional Chinese medicine acupoint stimulation theory with modern transcutaneous electrical stimulation (TEAS) technology. In particular, by combining transcutaneous acupoint electrical stimulation (TEAS) technology with an intelligent control module and adjustable electrical stimulation parameters, it provides users with personalized intervention plans and offers an innovative non-drug approach for autonomic nervous system regulation. This interdisciplinary integration not only avoids the side effects of traditional drugs but also effectively utilizes the advantages of traditional Chinese medicine, providing a safer, more comfortable, and more efficient regulation method. By providing comprehensive safety protection, intelligent adjustment, and a comfortable experience, this invention offers a completely new solution for autonomic nervous system regulation and has broad market application potential. The device effectively relieves symptoms such as nausea, vomiting, and dizziness caused by autonomic nervous system dysfunction by stimulating specific acupoints such as Neiguan (PC6) (verification method refers to Fang Jingjing, Jiang Yujia, Sun Chaoyue, Cai Mengcheng, You Yanli. Experimental study on the prevention and treatment of motion sickness by acupuncture at Neiguan acupoint [J]. Naval Medical Journal, 2024, 45(04): 366-370.). Compared with traditional drug therapy and bulky electrical stimulation devices, this invention provides a convenient, comfortable, intelligent and efficient means of autonomic nervous system regulation, which significantly improves the safety, comfort and intelligence of wearing acupoint electrical stimulation devices for a long time.

[0057] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A wearable transcutaneous electrical stimulation device, characterized in that: It includes electrode assemblies, a stimulation signal generation and output module, a monitoring and feedback module, a power management module, a core control and processing unit, and a user interface. These components work together through electrical connections. The electrode assembly includes a flexible raised substrate and a radial gradient impedance structure. The flexible raised substrate, as the electrode body, is integrally molded from conductive rubber material, and its contact surface is designed as a convex elongated elliptical structure. The radial gradient impedance structure controls the distribution concentration of conductive nanomaterials in the flexible raised substrate to make it exhibit a radially decreasing trend from the center to the edge, so that the electrode contact surface forms an impedance gradient that radially increases from the center to the edge. The stimulation signal generation and output module includes an electrical stimulation driver chip, a two-stage conversion output circuit, and a high-efficiency boost circuit. The two-stage conversion output circuit generates symmetrical bidirectional pulse electrical stimulation signals, and the high-efficiency boost circuit can boost the battery voltage to the required high voltage. Combined with the main control circuit, the electrical stimulation driver chip uses a point-plotting method to achieve multi-mode output. The monitoring and feedback module consists of an embedded sensor and a high-precision analog-to-digital converter module, and is used to monitor the impedance between the electrode and the skin in real time. The power management module uses a rechargeable lithium battery with a charging interface and has a built-in low-power management logic module that can automatically enter sleep mode or reduce power consumption according to the user's operation status, effectively extending the device's battery life. The core control and processing unit consists of a microprocessor and an edge computing and intelligent algorithm module integrated inside or outside the microprocessor. The microprocessor is responsible for real-time processing and analysis of data and controlling the electrical stimulation output. The edge computing and intelligent algorithm module is responsible for executing real-time decision-making and adaptive control. Based on real-time data, the module will automatically adjust the current output intensity, stimulation mode or heat management strategy. The user interface includes control buttons, stimulation indicator lights, and Bluetooth communication, enabling bidirectional signal transmission with the core control and processing unit.

2. The wearable transcutaneous electrical stimulation device according to claim 1, characterized in that: The electrode assembly consists of a pair of elastic composite dry electrodes. The electrodes are convex, elongated elliptical structures, and the working surfaces of the electrodes are processed into concave cylindrical shapes. The electrode substrate is made of medical-grade thermoplastic elastomer, which contains a mixture of conductive metal particles and one-dimensional conductive nanofibers uniformly dispersed inside, and is mixed using a gradient infusion method.

3. The wearable transcutaneous electrical stimulation device of claim 2, wherein: The elastic composite dry electrode is obtained through multi-layer screen printing or gradient infusion process, filling different concentrations of conductive metal particles in different radial regions of the raised electrode: in the central region of the top crown of the electrode, the filling amount of metal particles is higher than its percolation threshold, and the particles form a tight mutual contact, exhibiting low impedance characteristics, and serving as the main conduction channel of current; in the radial region extending from the center to the edge, the distribution density of metal particles is gradually reduced, increasing the polymer gap between the particles and forming a gradient impedance distribution.

4. The wearable, transcutaneous electrical stimulation device of claim 1, wherein: This includes a long-term burn risk detection algorithm. This algorithm does not require the use of temperature sensors. It relies on existing data on current, electrode area, and skin impedance to indirectly calculate the heat accumulation and heat dissipation status of the skin, and to assess the risk of burns in real time.

5. The wearable transcutaneous electrical stimulation device of claim 4, wherein: The algorithm for detecting the risk of long-term burns is as follows: 1) Calculation of instantaneous heat generation power density The core processor obtains real-time current based on the current sampling circuit. Electrode-skin impedance and the effective contact area determined by the electrode physical parameters Calculate the instantaneous heat generation power density : (1) 2) Dynamic heat dissipation estimation The system uses Newton's law of cooling to simulate the energy dissipation of skin to the environment. : (2) wherein, is the thermal conductivity coefficient, is the estimated temperature of the previous cycle, is the ambient temperature; 3) Recursive Iterative Algorithm for Skin Temperature The skin estimated temperature is tracked in real time by the following discretized iterative formula : (3) wherein is the total heat production power, is the heat conversion efficiency, and are the average specific heat capacity and the affected mass of the skin tissue, respectively; 4) The integrated risk assessment function (4) wherein, is a weight coefficient, which can be adjusted according to experimental data; is a safety threshold temperature, is a current set value; 5) Tiered response strategy and automatic recovery The intelligent control unit executes the following hierarchical safety logic depending on the real-time values of Level 1 warning stage: The system determines that there is a risk of long-term cumulative burns; at this time, the stimulation is not interrupted, but the "heat restriction mode" is entered, which slows down the heat generation by linearly reducing the pulse width or current intensity until the risk value drops. Level 2 Interruption Phase: The system determines that there is an immediate risk of damage or serious hardware failure; at this time, it immediately cuts off the output of the drive circuit, locks the device, and sends an alarm signal to the user through the indicator light. Smart recovery mechanism: when the risk value falls back to the safe interval and the impedance After the system is stable, it will use a slow start method to gradually restore the parameters to the user's initial setting value, ensuring the continuity and comfort of stimulation.

6. The method of controlling a wearable transdermal electrical stimulation device according to any one of claims 1-5, characterized in that: The specific steps are as follows: (1) System initialization and self-test: After receiving the wake-up signal, the power management module starts the low-power microprocessor and calls the user's historical preference model or default parameters from its non-volatile memory to complete the automatic loading of parameters; at the same time, the system executes the power-on self-test program to scan the battery voltage and circuit integrity. (2) Wearing detection and mode selection: The monitoring and feedback module sends a weak detection signal to the skin, measures the impedance value of the electrode-skin interface in real time, and judges that the contact state is good. Then the system enters the mode setting stage and automatically configures the stimulation mode and target current intensity according to the user's key input or preset rules. (3) Stimulation output and constant current control: The stimulation signal generation and output module drives the bipolar conversion circuit to output a symmetrical bidirectional pulse signal to eliminate net DC bias and prevent skin electrolysis; at the same time, the current sampling circuit collects the voltage signal on the sampling resistor in real time, converts it into the actual output current value and real-time load impedance data and feeds it back to the microprocessor; the microprocessor executes the constant current control algorithm based on the feedback data, dynamically adjusts the driving voltage or pulse width, and ensures that the actual current is always stable within ±10% of the target value; (4) Estimating subcutaneous heat accumulation and preventing low-temperature burns: In the parallel long-term burn risk modeling process, the core control and processing unit calculates the instantaneous output power in real time based on the collected current, voltage and impedance data, and constructs a skin heat load model to estimate the subcutaneous heat accumulation. This model combines the heat growth rate and current deviation to calculate the comprehensive risk assessment value. Once the risk value is detected to exceed the preset threshold or there is an electrode slippage trend, the system immediately triggers a graded safety response and automatically performs degraded output or shut-off protection. (5) End and hibernation: The microprocessor monitors the timer status, button operation and wearing status in real time; when it detects that the stimulation has ended, the user has turned off the device or has not worn it for a long time, the system automatically saves the effective parameters of this operation to the memory to update the personalized model, then cuts off the power supply to the peripheral device and enters the microampere-level low power hibernation mode, and waits for the next system wake-up.

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