Wireless battery-free electrical stimulation system and application thereof

Abstract

The invention discloses a wireless battery-free electrical stimulation system and application thereof. The system comprises an external transmitting end and a wireless battery-free stimulator. The external transmitting end is formed by sequentially connecting a signal source, a power amplifier and a transmitting coil; the wireless battery-free stimulator sequentially comprises a receiving coil, a voltage doubling rectifying unit, a voltage stabilizing unit, an oscillating unit, an output protection unit and a stimulating electrode along a signal link, the receiving coil receives a high-frequency alternating-current signal through electromagnetic induction coupling, the high-frequency alternating-current signal is subjected to voltage doubling rectifying to form a high-voltage direct-current signal, and then the high-voltage direct-current signal is subjected to voltage stabilizing to form direct-current bias voltage; and finally, the low-frequency stimulation signal is processed by the output protection unit and then is output to the target tissue by the stimulation electrode. The near-field inductive coupling wireless battery-free electrical stimulation system solves the technical problems that in the prior art, a near-field inductive coupling wireless battery-free electrical stimulation system is generally low in stimulation voltage, close in wireless working distance, high in position sensitivity, not matched in energy supply frequency and treatment frequency, non-adjustable in stimulation parameter and poor in system universality.

Description

Technical Field

[0001] This invention belongs to the technical field of electrical stimulation therapy equipment, and relates to a wireless, battery-free electrical stimulation system and its application. Background Technology

[0002] Electrical stimulation therapy is a therapeutic technique that applies electrical pulses to biological tissues to regulate tissue electrical activity, promote cellular responses, and improve tissue function recovery. It represents an important interdisciplinary area of ​​biomedical and engineering development. In recent years, electrical stimulation has shown broad application prospects in various fields such as pain management, functional rehabilitation, tissue regeneration, cardiac pacing, and targeted drug delivery. Particularly in tissue damage repair, electrical stimulation can accelerate the recovery process of various tissue injuries, including epidermal wounds, central and peripheral nerve injuries, by promoting cell proliferation, migration, and neural plasticity. Despite its proven efficacy, the practical application of electrical stimulation therapy faces a fundamental challenge: how to continuously and stably provide electrical energy to target tissues and output appropriate stimulation signals. Current clinical and experimental systems largely rely on external wired power supplies. While this method provides effective electrical stimulation, it limits patient activity and usage scenarios, and increases the risk of infection in implantation settings. Battery-powered devices improve portability, but they typically suffer from large size, heavy weight, frequent maintenance, and are not suitable for long-term wear or implantation, thus significantly hindering the further popularization and promotion of electrical stimulation therapy technology.

[0003] To address the shortcomings of wired power supply and battery-powered systems, various wireless, battery-free electrostimulation technologies have been developed in recent years. These technologies mainly include wireless power supply methods based on electromagnetic resonance, such as near-field inductive coupling and far-field antenna radiation; wireless power supply methods based on electromechanical conversion, such as piezoelectric or triboelectric devices driven by ultrasound or human motion; and wireless power supply methods based on photoelectric conversion, such as using the photoelectric response of electroactive materials to achieve stimulation output. Although these technologies have achieved wireless and battery-free operation to some extent, they still generally suffer from problems such as low stimulation voltage, unstable output, and limited stimulation conditions.

[0004] Among various wireless, battery-free solutions, near-field inductive coupling (NFC) technology, which uses magnetic field coupling between the transmitting and receiving coils to achieve energy transfer, offers advantages such as relatively simple structure, fewer side effects on biological tissues, easy compatibility with flexible printed circuit boards and integrated circuit processes, and suitability for low-cost and large-scale manufacturing. Therefore, it is widely considered the most promising approach for practical bioelectronic wireless therapy and has already been applied in various therapeutic scenarios, including spinal cord stimulation and cerebral cortex stimulation. Thus, near-field inductively coupled radio stimulation systems have significant research and application value. However, several key bottlenecks in its existing technologies remain to be addressed.

[0005] Existing near-field inductively coupled radio stimulation (ICR) systems primarily face a fundamental contradiction between miniaturization, energy transfer efficiency, and transmission distance. For wearable and implantable applications, receivers typically need to be centimeter-sized or even smaller to minimize foreign body sensation, reduce implantation burden, and accommodate limited anatomical space. However, as the size of the receiving coil decreases, its inductance and coupling efficiency simultaneously decline, resulting in a lower achievable induced voltage at the receiver. Meanwhile, as the distance between the transmitting and receiving coils increases, the coupling coefficient, transmission efficiency, and receiving voltage all continue to decrease, thus limiting the achievable wireless operating distance of existing systems while maintaining the required output voltage.

[0006] Secondly, existing near-field inductively coupled plasma (ICP) systems are highly sensitive to the relative position between the transmitter and receiver. In practical applications, it is difficult to maintain precise alignment between the transmitter and receiver coils for extended periods, regardless of whether the device is skin-attached or subcutaneously implanted. Even slight lateral offsets, longitudinal distance changes, or angular deviations between the transmitter and receiver can lead to a significant decrease in received power, resulting in fluctuations in the output stimulation voltage, and in severe cases, even causing the system to malfunction. These problems are particularly pronounced in implantable applications because, after implantation, the external transmitter can typically only be placed roughly near the implantation area, making continuous and precise alignment difficult. Furthermore, changes in geometric parameters such as coil diameter and number of turns can further affect output consistency. Therefore, existing technologies generally suffer from low position tolerance, high alignment requirements, and difficulty in maintaining stable stimulation conditions.

[0007] Furthermore, existing near-field inductively coupled plasma (NFC) systems suffer from a mismatch between the energy transfer frequency and the treatment frequency. To achieve high wireless energy transfer efficiency within a small size, the transmitting and receiving coils typically operate in the megahertz band; however, the stimulation frequencies required for biomedical stimulation therapy are usually only a few hertz to several hundred hertz. In other words, the coil efficiently receives high-frequency radio frequency signals, while the target tissue actually requires low-frequency stimulation signals. Without a dedicated downstream circuit to convert the received high-frequency signals, it is difficult to output a stimulation waveform that meets therapeutic requirements while maintaining high wireless energy transfer efficiency. Therefore, the mismatch between the wireless power supply frequency and the biotherapy frequency is a common problem in existing technologies, directly affecting the actual therapeutic effect of the system.

[0008] Furthermore, existing near-field inductively coupled wireless stimulation systems often suffer from the difficulty in widely configuring stimulation parameters. Different disease types, tissue sites, and individuals typically have significantly different requirements for stimulation amplitude, frequency, and pulse width. However, most existing systems can only provide fixed stimulation parameters, making it difficult to flexibly adapt to specific application scenarios. Therefore, existing technologies not only fail to meet the differentiated treatment needs under different pathological conditions but also hinder the reduction of R&D and manufacturing costs, making it difficult to develop a truly universal wireless stimulation platform with widespread application potential. In other words, existing technologies still have significant shortcomings in terms of universality, scalability, and platform-based design.

[0009] In summary, while existing wireless battery-free electrical stimulation technologies, especially near-field inductively coupled plasma (NFC) stimulation, offer significant advantages in wireless power supply, biocompatible manufacturing, and clinical application prospects, they still suffer from drawbacks such as low output voltage, limited working distance, mismatch between energy transmission and treatment frequencies, high sensitivity to coil misalignment, difficulty in widely configuring stimulation parameters, and insufficient system versatility. Therefore, there is an urgent need to provide a new wireless battery-free electrical stimulation system that, while maintaining the advantages of near-field inductive coupling, further improves output voltage, transmission distance, position tolerance, and parameter configurability, making it adaptable to different treatment scenarios and thus promoting the practical application of radiofrequency stimulation technology. Summary of the Invention

[0010] To address the problems existing in the prior art, this invention provides a wireless battery-free electrostimulation system and its application, thereby solving the technical problems commonly found in existing near-field inductive coupling wireless battery-free electrostimulation systems, such as low stimulation voltage, short wireless working distance, high position sensitivity, mismatch between power supply frequency and treatment frequency, non-adjustable stimulation parameters, and poor system versatility.

[0011] This invention is achieved through the following technical solution: A wireless, battery-free electrical stimulation system includes an external transmitter and a wireless, battery-free stimulator; The external transmitter includes a signal source, a power amplifier, and a transmitting coil that are electrically connected in sequence. The wireless battery-free stimulator includes, in sequence along the signal link, a receiving coil, a voltage doubler rectifier unit, a voltage regulator unit, an oscillation unit, an output protection unit, and a stimulation electrode; The output terminal of the signal source is connected to the input terminal of the power amplifier, and the output terminal of the power amplifier is connected to the transmitting coil, which is used to generate an alternating electromagnetic field. The receiving coil and the transmitting coil are coupled by electromagnetic induction to receive alternating electromagnetic fields and induce high-frequency alternating current signals. The voltage doubler rectifier unit converts the high-frequency AC signal into a high-voltage DC signal; The voltage regulator unit converts the high-voltage DC signal into a DC bias voltage; The oscillation unit generates a low-frequency stimulation signal based on the DC bias voltage. After the output protection unit performs safe processing on the low-frequency stimulation signal, it is output to the target tissue by the stimulation electrode.

[0012] Preferably, the receiving coil adopts a planar spiral structure with an inner diameter of 20 mm, 8 turns, a line width and line spacing of 0.13 mm, and an inductance of approximately 2.9 microhenries at the operating frequency.

[0013] Preferably, the voltage doubler rectifier unit is composed of multiple diodes and multiple capacitors connected in a cascaded manner.

[0014] Preferably, the voltage doubler rectifier unit is a four-stage voltage doubler rectifier circuit, which is composed of four Schottky diodes D1, D2, D3, D4 and four capacitors C1, C2, C3, C4 connected in a cascaded manner.

[0015] Preferably, the voltage regulation unit includes a low dropout linear regulator U1, an input filter capacitor C5, an output filter capacitor C6, resistors R1, R2, and R3; the low dropout linear regulator U1 has an input pin, a ground pin, an enable pin, an adjustment pin, and an output pin; The input pin is connected to the output terminal of the voltage doubler rectifier unit; the enable pin is connected to the output terminal of the voltage doubler rectifier unit; the adjustment pin is grounded through resistor R3, and resistor R2 is connected between the adjustment pin and the output pin; the output pin is connected to the input terminal of the subsequent oscillation unit; the input filter capacitor C5 is connected in parallel with resistor R1 and then connected between the input pin and ground; the output filter capacitor C6 is connected between the output pin and ground.

[0016] Preferably, the output voltage of the voltage regulator unit is: ; in, R 2 represents the resistance value of resistor R2; R 3 represents the resistance value of resistor R3.

[0017] Preferably, the oscillation unit includes a 555 timer U2, resistors R4, R5, and R6, capacitors C7, C8, and C9, and a Schottky diode D5; the 555 timer U2 has a ground pin, a trigger pin, an output pin, a reset pin, a control pin, a threshold pin, a discharge pin, and a power supply pin.

[0018] The trigger pin is connected to the threshold pin and grounded through capacitor C7; the output pin is connected to the input terminal of the subsequent output protection unit; the reset pin is connected to the power supply pin and to the output terminal of the voltage regulator unit; the control pin is grounded through capacitor C8; the discharge pin is connected to the power supply pin through resistor R6; resistor R4 and Schottky diode D5 are connected in parallel between the trigger pin and the discharge pin; resistor R5 is connected between the output pin and the power supply pin; capacitor C9 is connected between the power supply pin and ground.

[0019] Preferably, the frequency and duty cycle of the output voltage of the oscillation unit are respectively: ; ; in, R 4 represents the resistance value of resistor R4; R 6 represents the resistance value of resistor R6; C 7 represents the capacitance value of capacitor C7.

[0020] Preferably, the output protection unit includes a protection resistor R7, a capacitor C10, a protection resistor R8, and a resistor R9; the capacitor C10, the protection resistor R8, and the resistor R9 form a high-pass filter to filter out the DC component in the output signal. The protective resistor R7, capacitor C10, and protective resistor R8 are connected in sequence to form a series branch; one end of the series branch is connected to the output terminal of the oscillation unit, and the other end is connected to the final output terminal of the wireless battery-free stimulator; the resistor R9 is connected between the final output terminal of the wireless battery-free stimulator and ground; stimulation electrodes are respectively set at the final output terminal and ground to output stimulation signals to the target tissue.

[0021] The above-mentioned wireless battery-free electrical stimulation system is applied in at least one of the fields of tissue wound repair, peripheral nerve injury treatment, and cardiac pacing.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a wireless battery-free electrostimulation system. By constructing a complete architecture encompassing external transmission, internal reception, and signal link processing, this system effectively solves several technical bottlenecks inherent in near-field inductively coupled wireless battery-free electrostimulation systems. Firstly, addressing the issues of low stimulation voltage and short wireless working distance, the system incorporates a voltage multiplier rectifier unit within the wireless battery-free stimulator. This unit amplifies and rectifies the high-frequency AC signal induced by the receiving coil, converting it into a high-voltage DC signal. This increases the maximum achievable stimulation voltage and correspondingly extends the working distance while meeting output requirements. Secondly, addressing the issue of high position sensitivity, the system incorporates a voltage regulator within the wireless, battery-free stimulator. A low-dropout linear regulator converts the fluctuating input signal, which changes with the relative position of the coils, into a DC bias signal that remains relatively stable within a certain positional deviation range. This solves the problem of existing inductive coupling systems being easily affected by the relative position of the coils. To address the issues of mismatched power supply and treatment frequencies, unadjustable stimulation parameters, and insufficient versatility, the system includes an oscillation unit within the wireless, battery-free stimulator. This unit allows for controllable setting of the frequency and duty cycle of the output stimulation signal. Simultaneously, the DC bias voltage provided by the voltage regulator to the oscillation unit is adjustable, thereby enabling adjustable amplitude of the output stimulation signal. This design allows the stimulator's internal circuitry to generate stimulation signals with predetermined amplitudes, frequencies, and duty cycles according to application requirements, no longer limited to the high-frequency signals received by inductive coupling. Furthermore, due to the wide adjustable range of stimulation parameters and the standardized main circuitry of the stimulator, the system can be widely adapted to different tissues (such as nerves and skin), requiring only a change in electrode geometry, significantly improving the system's versatility and clinical applicability. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the wireless battery-free electrical stimulation system of the present invention; Figure 2 This is a schematic diagram of the overall principle of the wireless battery-free electrostimulation system of the present invention; Figure 3 This is a circuit diagram of the voltage multiplier rectifier unit of the stimulator of the present invention; Figure 4 This is a circuit diagram of the voltage regulation unit of the stimulator in this invention; Figure 5 This is a circuit diagram of the stimulator oscillation unit of the present invention; Figure 6This is a circuit diagram of the stimulator output protection unit of the present invention; Figure 7 To evaluate the therapeutic effect of the wireless, battery-free electrical stimulation system in rat skin wound repair in Example 2 of this invention, the following data is included: a) overall appearance of the rat wound model; b) photographs of the wound healing process; c) curve of relative wound area change over time; d) H&E staining of wound tissue; e) immunofluorescence staining of inflammation and regeneration-related molecules; f) quantitative analysis of relative skin thickness; g) quantitative analysis of wound closure time; h) quantitative analysis of IL-6 positive area; i) quantitative analysis of α-SMA positive area; j) quantitative analysis of CD31 positive area. In the figures, n=3, representing the sample size of the experiment, and *, **, and *** are statistical significance markers. P The value (probability value) reflects the likelihood that differences between groups are caused by random factors: * indicates P<0.05 The difference between groups was statistically significant; ** indicates P<0.01 The differences between groups were more statistically significant, *** indicating P<0.001 The difference between groups is statistically significant; ns indicates that the difference between groups is not statistically significant. Figure 8 The following are the in vivo experimental results of the wireless stimulation system for peripheral nerve repair in Example 3 of this invention, including: a) Schematic diagram of the implantation and stimulation process; b) Quantitative analysis of S100 protein expression; c) Quantitative analysis of βIII tubulin expression; d) Immunofluorescence staining of nerve tissue; e) H&E staining of gastrocnemius muscle tissue; f) Quantitative analysis of muscle fiber area; g) Quantitative analysis of gastrocnemius muscle wet weight; h) Changes in sciatic nerve function index (SFI) over time; i) Photographs of rat hindlimb functional status; In the figures, n=3, representing the sample size of the experiment, and ** and *** are statistical significance markers. P The value (probability value) reflects the likelihood that differences between groups are caused by random factors: ** indicates P<0.01 The differences between groups were more statistically significant, *** indicating P<0.001 The difference between groups is statistically significant; ns indicates that the difference between groups is not statistically significant. Figure 9 This diagram shows a comparison of the circuit principle and performance of the voltage doubler rectifier unit in the wireless battery-free stimulation system of this invention. Figure a shows the circuit diagram and output voltage waveform of a standard single-stage rectifier; figure b shows the circuit diagram and output voltage waveform of a four-stage voltage doubler rectifier unit; and figure c shows the maximum working distance under different combinations of coil turns and coil diameter when using a standard single-stage rectifier. D m Thermograph; d represents the maximum working distance under different combinations of coil turns and coil diameter when using a four-stage voltage multiplier rectifier unit. D m Heat map.

[0025] Figure 10 The figure shows the output stability characterization of the wireless battery-free stimulation system in this invention. Figure a represents the displacement misalignment characteristic curve, figure b represents the angle misalignment characteristic curve, and figure c represents the influence characteristic curve of coil geometric parameters. The dashed line represents the test results without a voltage regulator unit, and the solid line represents the test results with a voltage regulator unit. As can be seen from the figure, the wireless stimulation system exhibits extremely strong anti-misalignment capability (robustness) after the voltage regulator unit is installed: the system maintains relative stability of the output voltage even when there are significant changes in lateral and longitudinal displacement (Figure g) and when the coil undergoes a large angular deflection (Figure h). Furthermore, the system maintains a consistent output voltage for different diameters or numbers of turns of the receiving coil (Figure i). This demonstrates that the system can stably provide the required stimulation voltage in practical applications without requiring strict alignment or specific coil shape design.

[0026] Figure 11 The diagrams shown are verification diagrams of the configurability of the electrical stimulation output parameters in this invention. In the diagrams, a is the voltage output waveform at different stimulation amplitudes (1V–7.5V); b is the voltage output waveform at different stimulation frequencies (Hz–kHz); c is the voltage waveform at different duty cycles in the low duty cycle range (1%–50%); and d is the voltage waveform at different duty cycles in the high duty cycle range (50%–99%). Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0033] The present invention will now be described in further detail with reference to the accompanying drawings: Example 1 like Figure 1 As shown, the present invention provides a wireless battery-free electrical stimulation system, including an external transmitter and a wearable or implantable wireless battery-free stimulator; the external transmitter includes a signal source, a power amplifier and a transmitting coil connected in sequence; the wireless battery-free stimulator includes a receiving coil, a voltage doubler rectifier unit, a voltage regulator unit, an oscillation unit, an output protection unit and a stimulation electrode in sequence along the signal link; The output terminal of the signal source is connected to the input terminal of the power amplifier, and the output terminal of the power amplifier is connected to the transmitting coil, which is used to generate an alternating electromagnetic field. The receiving coil and the transmitting coil are coupled by electromagnetic induction to receive alternating electromagnetic fields and induce high-frequency alternating current signals. The output terminal of the receiving coil is connected to the input terminal of the voltage doubler rectifier unit, the output terminal of the voltage doubler rectifier unit is connected to the input terminal of the voltage regulator unit, the output terminal of the voltage regulator unit provides the operating voltage for the oscillation unit, the output terminal of the oscillation unit is connected to the input terminal of the output protection unit, and the output terminal of the output protection unit is connected to the stimulation electrode. The connection between the external transmitter and the wireless battery-free stimulator is a non-contact magnetic coupling connection. The transmitting coil of the external transmitter is energized with a high-frequency alternating current, thereby generating an alternating magnetic flux in the surrounding space. The receiving coil of the wireless battery-free stimulator is placed in this alternating magnetic field, and an induced electromotive force is generated at both ends of the receiving coil through the principle of electromagnetic induction, thereby forming a closed high-frequency alternating signal loop. There is no physical wire connection between the external transmitter and the wireless battery-free stimulator. Energy and driving signals are wirelessly transmitted through an air-core transformer composed of the transmitting and receiving coils. After receiving the high-frequency energy signal, the wireless battery-free stimulator processes it sequentially through the voltage doubler rectifier unit, the voltage regulator unit, the oscillation unit, and the output protection unit, and finally outputs a low-frequency electrical pulse for tissue stimulation by the stimulation electrode.

[0034] Specifically, this universal system generally consists of two main parts: an external transmitter located outside the body and a wireless, battery-free stimulator, i.e., a receiver, located near the treatment site. The external transmitter generates a high-frequency alternating signal and wirelessly transmits it to the stimulator; the wireless, battery-free stimulator receives the signal, converts it into a low-frequency stimulation signal suitable for biological tissue treatment, and then outputs it to the target tissue through stimulation electrodes.

[0035] More specifically, such as Figure 2 As shown, the external transmitter includes a signal source, a power amplifier, and a transmitting coil, which are electrically connected in sequence. The output of the signal source is connected to the input of the power amplifier to output a high-frequency AC signal. The output of the power amplifier is connected to the input of the transmitting coil to receive the high-frequency AC signal and amplify it to generate an amplified high-frequency electrical signal. The transmitting coil receives the amplified high-frequency electrical signal and converts it into a spatial alternating electromagnetic field to wirelessly transmit energy to the receiving coil of the wireless battery-free stimulator. In other words, the signal source outputs a high-frequency AC signal, the power amplifier amplifies the signal, and the transmitting coil converts the amplified high-frequency electrical signal into a spatial alternating electromagnetic field.

[0036] The wireless, battery-free stimulator is the core component of this invention. Along the signal path, it sequentially includes a receiving coil, a voltage multiplier rectifier unit, a voltage regulator unit, an oscillation unit, an output protection unit, and a stimulation electrode. The output terminal of the receiving coil is electrically connected to the input terminal of the voltage multiplier rectifier unit, used to transmit the high-frequency AC signal induced by the received external alternating magnetic field to the voltage multiplier rectifier unit. The output terminal of the voltage regulator unit is electrically connected to the power supply terminal of the oscillation unit, used to provide a stable DC bias voltage to the oscillation unit. The signal output terminal of the oscillation unit is electrically connected to the input terminal of the output protection unit, used to transmit the generated low-frequency stimulation signal to the output protection unit. The output terminal of the output protection unit is electrically connected to the stimulation electrode, used to output the safely processed low-frequency stimulation signal to the target biological tissue.

[0037] The aforementioned units are sequentially linked around the overall function of radio stimulation, forming a complete energy transfer and signal processing chain. Specifically, the system first receives the high-frequency signal transmitted from the external transmitter through the receiving coil, then rectifies and boosts the signal through the voltage doubler rectifier unit to obtain a high-voltage DC signal. The DC voltage is then stabilized by the voltage regulator unit to prevent it from being affected by input fluctuations. On this basis, the DC signal is further converted into a low-frequency AC signal that meets the treatment requirements through the oscillation unit, and necessary safety processing is performed before output. Finally, the signal is applied to the target tissue through the stimulation electrodes.

[0038] The receiving coil is used to receive the alternating magnetic field generated by the external transmitter and induce a high-frequency alternating current signal. The receiving coil adopts a planar helical structure. The receiving coil has an inner diameter of 20 mm, 8 turns, a line width of 0.13 mm, and a line spacing of 0.13 mm, exhibiting an inductance of approximately 2.9 μH and a resistance of approximately 2.5 ohms at an operating frequency of approximately 4 MHz. This size and parameter represent a trade-off between coupling efficiency, positional tolerance, and size constraints for wearable / implantable applications.

[0039] The high-frequency AC signal output from the receiving coil first enters the voltage doubler rectifier unit. For example... Figure 3As shown, the voltage doubler rectifier unit is based on a Schottky diode (Skyworks Solutions Inc., SMS3922-079LF) and is a multi-stage voltage doubler structure, consisting of multiple diodes and capacitors connected in a cascaded manner. It is used to convert high-frequency AC signals into higher-voltage DC signals. Its basic working process is as follows: in different half-cycles of the high-frequency AC signal, each stage of the capacitor is charged sequentially through the diode, and the voltage on the multiple capacitors accumulates stage by stage, thus obtaining a higher DC output voltage at the output terminal than a conventional rectifier. Since the signal voltage directly obtained by the receiving coil is relatively low, the purpose of setting up the voltage doubler rectifier unit is twofold: first, to increase the usable output voltage of the system; and second, to increase the allowable operating distance under the same stimulus output requirements. Figure 3 As shown, in a preferred embodiment, the voltage doubler rectifier unit is a four-stage voltage doubler structure, with an output capability approximately four times that of a conventional rectifier. Specifically, the voltage doubler rectifier unit includes capacitors C1, C2, C3, and C4, and diodes D1, D2, D3, and D4. Capacitor C1 and diode D1 form the first-stage voltage doubler circuit, capacitor C3 and diode D2 form the second-stage voltage doubler circuit, capacitor C2 and diode D3 form the third-stage voltage doubler circuit, and capacitor C4 and diode D4 form the fourth-stage voltage doubler circuit. The input terminal (…) A capacitor (C1) is connected to the cathode of diode D1, and the anode of diode D1 is grounded. One end of capacitor C2 is connected to the anode of diode D2, and the other end is connected to the cathode of diode D3. The cathode of diode D2 is connected to one end of capacitor C3, and the other end of capacitor C3 is grounded. The anode of diode D3 is connected to one end of capacitor C4, and the other end of capacitor C4 is connected to the cathode of diode D4, which serves as the high-voltage DC output terminal. ).

[0040] In this circuit, diodes D1, D2, D3, and D4 are all Schottky diodes, used to reduce the forward voltage drop and improve rectification efficiency. The input signal first enters the first-stage voltage multiplier circuit, where it is rectified by diode D1 and capacitor C1 to generate a first-stage DC component. This component is then superimposed with the subsequent input signal and enters the second stage, where it undergoes multi-stage voltage multiplication rectification, passing sequentially through diode D2 and capacitor C3, diode D3 and capacitor C2, and diode D4 and capacitor C4. Figure 9 As shown in a and b, due to the adoption of a four-stage voltage multiplier structure, the final output voltage of the voltage multiplier rectifier unit is approximately four times the peak input AC voltage, and its output capability is approximately four times that of a conventional single-stage rectifier, thus meeting the high voltage requirements of wireless battery-free stimulators. Furthermore, under the same stimulation voltage conditions, the voltage multiplier rectifier unit can increase the working distance compared to a conventional single-stage rectifier. For example... Figure 9As shown in c and d, under the condition of maintaining a stable ±3V output stimulation voltage, the system using a voltage doubler rectifier unit has a longer maximum working distance than the system using a conventional single-stage rectifier. D m It increases by about 5 to 7 mm.

[0041] The output of the voltage doubler rectifier unit is then input to the voltage regulator unit. For example... Figure 4 As shown, the voltage regulator unit employs a low-dropout linear regulator (MaxLinear, Inc., SPX5205M5-L / TR). Its input is connected to the output of the voltage doubler rectifier unit, and its output is connected to the power supply of the subsequent oscillation unit. The voltage regulator unit features an adjustable output configuration; the start-up terminal is pulled high to enable the voltage regulation function, and input and output filter capacitors are included to reduce noise and stabilize the output. The function of the voltage regulator unit is to transform the DC input, which fluctuates with the coil position of the preceding stage, into a relatively constant DC output. In other words, even if the wireless energy received by the preceding stage fluctuates due to misalignment, the subsequent stage can still obtain a stable bias voltage, thereby avoiding drastic fluctuations in the stimulation voltage with position changes. Furthermore, the voltage regulator unit can also reduce the impact of changes in coil diameter and number of turns on the output stimulation, thereby increasing the flexibility of different coil shape designs and facilitating adaptation to different anatomical sites.

[0042] In a preferred embodiment, such as Figure 4 As shown, the voltage regulation unit includes a low-dropout linear regulator U1, an input filter capacitor C5, an output filter capacitor C6, resistors R1, R2, and R3; the low-dropout linear regulator U1 has an input pin (VIN), a ground pin (GND), an enable pin (EN), an adjustment pin (ADJ), and an output pin (VOUT); the input pin (VIN) is connected to the output terminal of the voltage doubler rectifier unit (…). ), used to receive unstable DC input voltage; the enable pin (EN) is connected to the output terminal of the voltage doubler rectifier unit ( This enables the low-dropout linear regulator U1; the adjustment pin (ADJ) is grounded through resistor R3, and resistor R2 is connected between the adjustment pin (ADJ) and the output pin (VOUT) to set the output voltage value; the output pin (VOUT) is connected to the power supply terminal of the subsequent oscillation unit. The input filter capacitor C5 is connected in parallel with the resistor R1 and then connected between the input pin (VIN) and ground. The output filter capacitor C6 is connected between the output pin (VOUT) and ground.

[0043] Specifically, the voltage regulation unit adopts an adjustable output configuration with a low-dropout linear regulator U1 as its core, and its specific connection relationship is as follows: Power supply connection: The input pin (VIN) of the low dropout linear regulator U1 is connected to the output terminal of the preceding voltage doubler rectifier unit. A resistor R1 and an input filter capacitor C5 are connected in parallel between the input pin (VIN) and ground to improve circuit stability and filter out high-frequency noise at the input.

[0044] Enable connection: The enable pin (EN) of the low dropout linear regulator U1 is directly connected to the input terminal ( This activates the voltage regulation function by pulling the pin high.

[0045] Feedback regulation connection: The adjustment pin (ADJ) of the low dropout linear regulator U1 is connected to the output terminal (VOUT) through resistor R2 and grounded through resistor R3. Resistors R2 and R3 form a feedback resistor network used to set the output voltage of the regulator unit.

[0046] Output connection: The output pin (VOUT) of the low dropout linear regulator U1 serves as the output terminal of the voltage regulation unit. The output pin (VOUT) is connected to the subsequent oscillation unit. An output filter capacitor C6 is connected between the output pin (VOUT) and ground to stabilize the output voltage and reduce ripple.

[0047] The voltage regulator unit transforms the fluctuating DC input voltage caused by coil position changes in the preceding stage into a relatively constant DC output voltage. Even if the wireless energy received by the preceding stage fluctuates due to coil misalignment, the subsequent circuitry can still obtain a stable bias voltage, thus avoiding drastic fluctuations in the stimulation voltage with position changes. Furthermore, this voltage regulator unit can also reduce the impact of changes in coil diameter and number of turns on the output stimulation, thereby increasing the flexibility of different coil shape designs and facilitating adaptation to different anatomical sites. Figure 10 As shown, under conditions of 18 mm lateral offset, 15 mm longitudinal offset, and ±40 degrees angular deflection, the system can still maintain a stable output of approximately ±3 volts. This demonstrates that the wireless stimulation system possesses extremely strong anti-misalignment capabilities; it maintains relative stability in output voltage even with significant changes in lateral and longitudinal displacement and large angular deflections of the coil. Furthermore, the system maintains a consistent output voltage for different diameters or numbers of turns of the receiving coil, proving that the system can stably provide the required stimulation voltage in practical applications without requiring stringent alignment or specific coil shape design.

[0048] The DC voltage output from the voltage regulator unit is then used as the power supply bias for the oscillation unit. For example... Figure 5As shown, the oscillation unit is built based on a 555 timer (UMW, NE555DR) and is used to convert a stable DC voltage back into a low-frequency signal suitable for biotherapy. Specifically, the oscillation unit includes a 555 timer U2, resistors R4, R5, and R6, capacitors C7, C8, and C9, and a Schottky diode D5; the 555 timer U2 has a ground pin (GND), a trigger pin (TRIG), an output pin (OUT), a reset pin (RESET), a control pin (CONT), a threshold pin (THRES), a discharge pin (DISCH), and a power supply pin (VCC).

[0049] The trigger pin (TRIG) is connected to the threshold pin (THRES) and grounded through capacitor C7; the output pin (OUT) is connected to the input terminal of the subsequent output protection unit. The reset pin (RESET) is connected to the power supply pin (VCC) and to the output of the voltage regulator unit. The control pin (CONT) is grounded through capacitor C8; the discharge pin (DISCH) is connected to the power supply pin (VCC) through resistor R6; resistor R4 and Schottky diode D5 are connected in parallel between the trigger pin (TRIG) and the discharge pin (DISCH); resistor R5 is connected between the output pin (OUT) and the power supply pin (VCC); and capacitor C9 is connected between the power supply pin (VCC) and ground.

[0050] That is, the oscillation unit is built based on the 555 timer U2 and is used to stabilize the DC voltage output by the voltage regulator unit ( This is converted into a low-frequency pulse signal suitable for biological therapy. The specific connection relationship and working principle are as follows: Power supply and filtering: The power supply pin (VCC) of the 555 timer U2 is connected to the output of the pre-stage voltage regulator unit. The ground pin (GND) is connected to ground. Capacitor C9 is connected between the power supply pin (VCC) and ground for power supply decoupling; capacitor C8 is connected between the control pin (CONT) and ground to stabilize the reference voltage of the internal comparator.

[0051] Timing network connection: The capacitor C7 serves as a timing capacitor, with one end connected to the threshold pin (THRES) and trigger pin (TRIG) of the 555 timer U2, and the other end grounded.

[0052] Charging and discharging path configuration: The resistor R4 and the Schottky diode D5 are connected in parallel between the power supply pin (VCC) and the threshold pin (THRES) to form a charging circuit; the resistor R6 is connected between the discharge pin (DISCH) and the power supply pin (VCC) to form a discharging circuit.

[0053] Signal output: The output pin (OUT) of the 555 timer U2 is connected to the power supply pin (VCC) through the resistor R5, and serves as the output terminal of the oscillation unit. It provides drive for subsequent circuits.

[0054] Through the above connection, the amplitude of the output signal of the oscillation unit is determined by the output voltage of the voltage regulator unit ( The frequency and duty cycle of the output signal are determined by the parameters of resistors R4 and R6, and capacitor C7. The introduction of the Schottky diode D5 makes the charging and discharging paths of capacitor C7 independent, thereby achieving a wide range of duty cycle adjustment from 1% to 99% to meet the needs of different treatment scenarios.

[0055] That is, the output voltage of the voltage regulator unit V o3 The amplitude of the oscillator output voltage is directly determined by the resistance and capacitance parameters of the oscillator unit, while the frequency and duty cycle of the output voltage are determined by these parameters. Specifically, the output voltage of the voltage regulator unit... V o3 The resistance can be adjusted R 2 and resistance R 3. Configure it as follows: (1); The frequency and duty cycle of the oscillator are determined by the resistor. R 4. Resistance R 6 and capacitor C 7. Adjustments are made, namely: (2); (3); In the design, a Schottky diode D5 (Skyworks Solutions Inc., SMS3922-079LF) was also added to the oscillation branch to make the capacitor C 7. Charging and discharging follow different paths, thereby widening the duty cycle adjustment range. This design allows the output parameters of this invention to cover a wider range. For example... Figure 11As shown, the system output amplitude can be adjusted between approximately 1 volt and 7.5 volts, with a peak-to-peak value of approximately 15 volts; the frequency can be adjusted between the Hertz and kilohertz ranges; and the duty cycle can be adjusted between 1% and 99%. Therefore, the same main circuit can meet the different requirements for stimulation parameters in various treatment scenarios.

[0056] The low-frequency signal output by the oscillation unit then enters the output protection unit. For example... Figure 6 As shown, the output protection unit includes a protection resistor R7, a capacitor C10, a protection resistor R8, and a resistor R9. The capacitor C10, the protection resistor R8, and the resistor R9 form a high-pass filter to filter out the DC component in the output signal.

[0057] The protective resistor R7, capacitor C10, and protective resistor R8 are connected in sequence to form a series branch; one end of the series branch is connected to the output terminal of the oscillation unit. The other end is connected to the final output of the wireless battery-free stimulator. The resistor R9 is connected to the final output terminal of the wireless battery-free stimulator. Between and ground; the final output terminal ( Stimulation electrodes are placed on the ground and the ground respectively to output stimulation signals to the target tissue.

[0058] The output protection unit is located between the oscillation unit and the stimulation electrode to limit the current magnitude, filter out the DC component, and improve biosafety. Its specific connection relationship and function are as follows: Current limiting and coupling: Low-frequency signal output by the oscillator unit ( First, the signal passes through a protective resistor R7, which limits the maximum output current to prevent overcurrent damage to the tissue. Then, the signal is DC isolated by a capacitor C10.

[0059] High-pass filter configuration: The coupling capacitor C10, along with the protection resistors R8 and R9, constitute a high-pass filter. One end of the protection resistor R8 is connected to the capacitor C10, and the other end is connected to the output terminal. One end of resistor R9 is connected to the output terminal ( The other end is grounded. The cutoff frequency of the high-pass filter is determined by the parameters of the coupling capacitor C10, the protection resistor R8, and the resistor R9. It is used to filter out the DC component in the output signal, so that the stimulation signal applied to the tissue maintains a near-zero DC component, thereby reducing electrode polarization and tissue charge accumulation.

[0060] That is, the output protection unit includes a protection resistor. R 7 and a resistor-capacitor high-pass filter, the resistor-capacitor high-pass filter comprising C10 , R 8 and R 9. The protective resistor limits the current; the high-pass filter removes the DC component from the output, ensuring the stimulation signal applied to the tissue has a near-zero DC component, thereby reducing electrode polarization, tissue charge accumulation, and potential damage risks. This dual protection mechanism ensures both stimulation effectiveness and biocompatibility as much as possible. The main circuit design remains unchanged across different treatment scenarios; for different target tissues, only the geometry of the stimulation electrodes needs to be adapted to the size and geometry of the target tissue.

[0061] Finally, the low-frequency signal, processed by the output protection unit, is output to the target tissue via the stimulation electrode. It is important to note that the main circuit design of this invention remains unchanged across different treatment scenarios; the aforementioned receiving, rectification, voltage regulation, and oscillation links do not need to be redesigned due to different treatment targets. For different target tissues, only the geometry of the stimulation electrode needs to be adapted to the size and geometry of the target tissue.

[0062] Example 2 This embodiment takes an electrical stimulation therapy experiment for skin wound repair as an example, aiming to verify the in vivo therapeutic effect of the wireless battery-free electrical stimulation system of the present invention, especially its effect on promoting the repair of full-thickness skin wounds.

[0063] Experimental setup and stimulus parameters like Figure 7 As shown in Figure a, rats were used as the animal model in the experiment. The electrical stimulator was applied using an adhesive method, with the main body of the device placed on the skin surface near the wound, and the stimulating electrodes contacting the tissues on both sides of the wound to establish an effective electric field pathway.

[0064] In this embodiment, the electrical stimulation parameters are set as follows: Electric field strength: 5 V / cm Frequency: 100 Hz Duty cycle: 50% Duration of a single stimulation session: 10 minutes Stimulation frequency: once every other day Animal models and experimental groups A rat back splint-type full-thickness skin wound model was used to strictly control wound contraction. The experiment was divided into two groups: Self-healing group: Only routine wound care was performed, without the application of electrical stimulation.

[0065] Stimulation group: Electrical stimulation was applied according to the parameters described above.

[0066] Macroscopic observation and quantitative analysis of wound healing Figure 7 b shows the macroscopic healing status of the wound on days 0, 3, 6, and 9. The comparison shows that the wound healing rate in the stimulation group was significantly faster than that in the self-healing group.

[0067] Figure 7 c is a quantitative statistical graph showing the change in relative wound area over time. The experimental results showed that the stimulation group achieved wound closure around day 9, while the self-healing group closed around day 11, representing an increase in healing speed of approximately 25%. This indicates that electrical stimulation significantly accelerated the wound closure process.

[0068] Histological analysis (H&E staining) Figure 7 d shows the hematoxylin-eosin (H&E) staining results of the wound tissue. Compared with the self-healing group, the skin structure formed in the stimulation group was closer to that of the normal group, with a more intact epidermis and significantly increased skin thickness.

[0069] Figure 7 f represents the quantitative statistics of relative skin thickness. The data show that the skin thickness in the stimulation group was significantly higher than that in the self-healing group, and closer to the level of normal skin. Figure 7 Further analysis showed that the wound closure time in the stimulation group was significantly shorter than that in the self-healing group.

[0070] Immunofluorescence staining and analysis of inflammation and repair markers Figure 7 e represents the immunofluorescence staining results, used to assess inflammation levels (IL-6), myofibroblast (α-SMA) levels, and angiogenesis (CD31). The specific results are as follows: Inflammation levels (IL-6): such as Figure 7 As shown in h, the percentage of IL-6 positive area in the stimulation group was significantly lower than that in the self-healing group, indicating that electrical stimulation effectively reduced the inflammatory response of the wound.

[0071] Myofibroblasts (α-SMA): such as Figure 7 As shown in i, the percentage of α-SMA positive area in the stimulation group was significantly higher than that in the self-healing group ( P The value <0.001 indicates that electrical stimulation promotes the proliferation and migration of myofibroblasts, which is beneficial for wound contraction and remodeling.

[0072] Angiogenesis (CD31): such as Figure 7 As shown in j, the percentage of CD31-positive area in the stimulation group was significantly higher than that in the self-healing group ( P <0.001), indicating that electrical stimulation promoted the formation of new blood vessels, providing sufficient nutrition and oxygen for wound repair.

[0073] In summary, this embodiment, using a rat full-thickness skin wound model, verified that the electrostimulation system described in this invention can significantly accelerate wound healing, promote skin structure reconstruction, reduce inflammation levels, and optimize key repair indicators such as myofibroblasts and angiogenesis. This system has significant clinical application potential in the treatment of skin wounds.

[0074] In this embodiment, the stimulator for skin wound treatment is applied using an adhesive method. The device is placed on the skin surface near the wound, with the stimulation electrodes contacting the tissue on both sides of the wound. The corresponding stimulation parameters are set to an electric field strength of 5 volts per centimeter, a frequency of 100 Hz, and a duty cycle of 50%, with each stimulation lasting 10 minutes and repeated every other day. Animal experiments were conducted using a rat back 6 mm splint-restricted full-thickness skin wound model. Results showed that the stimulated group achieved wound closure around day 9, while the self-healing group closed around day 11, representing an approximately 25% increase in healing speed. Further histological results indicated that the skin structure formed in the stimulated group was closer to that of the normal group, with greater skin thickness, lower inflammation levels, and better indicators related to myofibroblasts and angiogenesis, demonstrating that this system can significantly promote wound repair.

[0075] Example 3 This embodiment uses an electrical stimulation therapy experiment for peripheral nerve repair as an example to verify the in vivo therapeutic effect of the wireless, battery-free electrical stimulation system described in this invention in peripheral nerve repair. Specifically: Experimental setup and stimulus parameters like Figure 8 As shown in Figure a, in this embodiment, the electrical stimulator is implanted subcutaneously. Specifically, the stimulating electrodes are fixed to the proximal and distal ends of the damaged nerve, and then the entire stimulator body is implanted in the subcutaneous tissue. An external transmitter is placed near the skin surface to wirelessly power the implanted stimulator, achieving wireless stimulation.

[0076] In this embodiment, the preferred electrical stimulation parameters are as follows: Electric field strength: 2 V / cm Frequency: 20 Hz Duty cycle: 10% Duration of a single stimulation session: 10 minutes Stimulation frequency: once every other day Animal models and experimental groups The experiment used a rat model of sciatic nerve compression injury. The experiment was divided into three groups: Normal group (Normal): Healthy rats that have not undergone surgical damage.

[0077] Self-healing (SH): Nerve injury surgery was performed, but no electrical stimulation was applied.

[0078] Stimulation group (Stim.): Nerve injury surgery was performed, and electrical stimulation was applied according to the above parameters.

[0079] Analysis of expression of biomarkers related to neural repair Figure 8 b and Figure 8 Figures c show the quantitative analysis of S100 and βIII tubulin, markers related to nerve repair. The results showed that the percentage of S100 and βIII tubulin expression area in the stimulation group was significantly higher than that in the self-healing group, and approached the level of the normal group. This indicates that electrical stimulation significantly promoted the regeneration of damaged nerves.

[0080] Figure 8 Image d shows the immunofluorescence staining results of neural tissue, which further demonstrates that the expression levels of S100 (green, labeled Schwann cells) and βIII tubulin (green, labeled nerve axons) are significantly increased in the stimulation group, and the neural structure is more intact.

[0081] Evaluation of muscle protection effect Figure 8 e shows the hematoxylin-eosin (H&E) staining results of the gastrocnemius muscle. Compared with the self-healing group, the muscle fibers in the stimulation group were more neatly arranged and the degree of atrophy was less.

[0082] Figure 8 f and Figure 8 g represents the quantitative statistics of muscle area and wet weight. Data shows that the muscle area and wet weight in the stimulation group were significantly higher than those in the self-healing group, indicating that electrical stimulation effectively slowed down muscle atrophy caused by nerve damage and played a good role in muscle protection.

[0083] Evaluation of neurological function recovery Figure 8 h represents the curve of sciatic nerve function index (SFI) over time. The results showed that the SFI value of the stimulation group was significantly better than that of the self-healing group after four weeks, with a functional improvement of about 40%, indicating better recovery of nerve conduction function.

[0084] Figure 8 i is a macroscopic photograph of the recovery of foot function in rats. It can be seen that the toe spread and foot grounding state in the stimulation group are closer to those in the normal group, while the self-healing group shows obvious foot drop and functional impairment.

[0085] In summary, the stimulator used in this embodiment for peripheral nerve treatment is implanted subcutaneously. The stimulating electrodes are fixed to the proximal and distal ends of the damaged nerve, respectively. The entire stimulator is placed subcutaneously, with the external transmitter located near the skin surface for wireless power supply. The preferred stimulation parameters are an electric field strength of 2 volts per centimeter, a frequency of 20 Hz, a duty cycle of 10%, and stimulation for 10 minutes per session, repeated every other day. A rat sciatic nerve compression injury model was used in animal experiments. Experimental results showed that the expression of nerve repair-related markers S100 and βIII tubulin in the stimulation group was significantly higher than in the self-healing group. The stimulation group also exhibited larger muscle fiber area and less severe gastrocnemius muscle mass loss, indicating better nerve regeneration and muscle protection effects. Functional evaluation results showed that the sciatic nerve function index in the stimulation group was significantly better than that in the self-healing group after four weeks, showing an improvement of approximately 40%. Furthermore, the toe spread and foot grounding were closer to the normal group, indicating that the system can significantly promote peripheral nerve repair and motor function recovery. In other words, the results of this embodiment demonstrate that the electrical stimulation system of the present invention can significantly promote peripheral nerve regeneration, effectively protect target muscles, and significantly improve the recovery of motor function.

[0086] In summary, this invention, through the organic cooperation of the receiving coil, voltage doubler rectifier unit, voltage regulator unit, oscillation unit, and output protection unit, realizes a complete link from high-frequency wireless power supply to low-frequency safe stimulation output, and solves the problems of insufficient output voltage, position offset sensitivity, frequency mismatch, inability to widely configure parameters, and difficulty in platform adaptation of existing near-field inductively coupled stimulation systems.

[0087] Specifically, this invention incorporates a voltage doubler rectifier unit after the receiving coil, which converts the originally low-amplitude high-frequency AC signal induced by the receiving coil into a higher-voltage DC output, thereby significantly improving the system's usable output voltage. For example... Figure 9 As shown, the DC voltage output by the voltage doubler rectifier unit is approximately four times that of a conventional single-stage rectifier, enabling the system to achieve a peak-to-peak output of approximately 15 volts, significantly enhancing the output capability of the wireless battery-free stimulator. This design addresses the common problem of insufficient output voltage in existing small wireless stimulators due to receiver size limitations, allowing the system to meet the stimulation intensity requirements of more treatment scenarios. Furthermore, in applications where only a lower stimulation voltage is needed to meet treatment requirements, this voltage enhancement can be further translated into an increased working distance. In other words, while maintaining the same output voltage, this invention can achieve a greater wireless transmission distance. Experimental results show that, under the condition of maintaining a stable ±3V output stimulation voltage, the system using the voltage doubler rectifier unit has a greater maximum working distance ( ) than the system using a conventional single-stage rectifier. D m The height is increased by approximately 5 to 7 mm. This allows for more flexible placement and greater usability in scenarios such as wearable on the skin, diaphragmatic power supply, and external power supply after implantation.

[0088] In addition, such as Figure 10 As shown, this invention, through the setting of a voltage stabilizing unit, enables the system to maintain a relatively constant stimulation output even when there is a certain positional deviation between the transmitting and receiving ends. Experimental results show that under conditions of lateral offset of 18 mm, longitudinal offset of 15 mm, and angular deflection of ±40 degrees, the system can still maintain a stable output of approximately ±3 volts. This indicates that the wireless stimulation system has extremely strong anti-misalignment capability; even with significant changes in lateral and longitudinal displacement and large angular deflections of the coil, the system can maintain a relatively stable output voltage. Furthermore, the system can maintain a consistent output voltage for different diameters or numbers of turns of the receiving coil, proving that the system can stably provide the required stimulation voltage in practical applications without strict alignment or specific coil shape design. This design effectively overcomes the problems of existing inductive coupling systems, which require high precision alignment of the transmitting and receiving coils and are prone to output fluctuations during actual use. In other words, this invention can significantly improve the system's tolerance to positional changes, enabling it to maintain relatively stable stimulation conditions even under practical conditions such as human movement, wear misalignment, adhesion errors, or difficulty in precise alignment of the external transmitting end after implantation. Meanwhile, the coil's geometric parameters can be adjusted to suit the size and curvature of the actual human body application without affecting the stimulator's output voltage. Therefore, this design provides wearable and implantable electrical stimulation systems with higher output stability, better ease of use, and greater practical application feasibility.

[0089] In addition, this invention incorporates an oscillation unit that can reconstruct the high-frequency power supply signal used for efficient wireless power transmission into the low-frequency stimulation signal actually required for biotherapy, thereby solving the mismatch between the high-efficiency wireless power transmission frequency and the stimulation frequency for biotherapy. Furthermore, this invention, through the design and adjustment of key resistor and capacitor parameters in the voltage regulation unit and oscillation unit, allows for flexible configuration of the output signal's amplitude, frequency, and duty cycle within a wide range. Specifically, as... Figure 11 As shown, the system can achieve frequency adjustment from the Hertz to the kilohertz level, output amplitude adjustment from approximately 1 volt to 7.5 volts, and duty cycle adjustment from 1% to 99%. This design overcomes the problems of existing wireless stimulation systems with fixed output parameters, applicable only to a few specific diseases or single treatment conditions, enabling the same main circuit to adapt parameters according to different tissue types, pathological states, and treatment needs. Therefore, this invention significantly improves the system's platformization and versatility, reducing the complexity and cost of repeatedly developing complete stimulation systems for different diseases or application scenarios.

[0090] Finally, this invention incorporates an output protection unit at the output end. This unit limits the output current through a series protection resistor and utilizes a resistor-capacitor high-pass filter to maintain a near-zero DC component in the output stimulation signal. This effectively reduces the risks of DC leakage, electrode polarization, and tissue damage, thereby improving the system's biostimulation safety. Related experimental results demonstrate that the system exhibits good biocompatibility, with no significant adverse reactions such as cytotoxicity, thermal damage, or infection observed. Furthermore, this invention has achieved clear effects in actual biotherapy. Animal experiments show that the system can increase the healing speed of skin wounds by approximately 25% and improve functional recovery after peripheral nerve injury by approximately 40%. Therefore, this invention not only realizes the circuit design and functional verification of a radio-frequency stimulation system but also possesses clear application value and promising commercialization prospects.

[0091] This invention discloses a wireless, battery-free electrostimulation system, comprising an external transmitter and a wireless, battery-free stimulator. The stimulator, along the signal link, sequentially includes a receiving coil, a voltage doubler rectifier unit, a voltage regulator unit, an oscillation unit, an output protection unit, and stimulation electrodes. The voltage doubler rectifier unit converts the high-frequency, low-voltage signal output from the receiving coil into a higher-voltage DC output, thereby improving the stimulator's output capability and increasing the working distance under the same target output conditions. The voltage regulator unit ensures that the system maintains a relatively constant stimulation output even when the transmitter and receiver experience lateral offset, longitudinal spacing changes, or angular deflection, achieving position-insensitive operation. Simultaneously, the output voltage remains consistent under different coil geometric parameters, allowing adjustment of coil geometric parameters based on the size, curvature, and other shape conditions of the actual human body application site without affecting the output stimulation voltage. The oscillation unit reconstructs the high-frequency wireless power supply signal into a low-frequency stimulation signal suitable for biological therapy, and the output amplitude, frequency, and duty cycle are configurable by adjusting key RC parameters, enabling the same system to be universally applied to different treatment scenarios. An output protection unit is set at the output end, in which a series protection resistor is used to limit the output current and a resistor-capacitor high-pass filter network is used to suppress the DC component, so that the output stimulus is kept close to zero DC component, thereby improving biological safety.

[0092] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wireless, battery-free electrical stimulation system, characterized in that, Includes external transmitters and wireless, battery-free stimulators; The external transmitter includes a signal source, a power amplifier, and a transmitting coil that are electrically connected in sequence. The wireless battery-free stimulator includes, in sequence along the signal link, a receiving coil, a voltage doubler rectifier unit, a voltage regulator unit, an oscillation unit, an output protection unit, and a stimulation electrode; The output terminal of the signal source is connected to the input terminal of the power amplifier, and the output terminal of the power amplifier is connected to the transmitting coil, which is used to generate an alternating electromagnetic field. The receiving coil and the transmitting coil are coupled by electromagnetic induction to receive alternating electromagnetic fields and induce high-frequency alternating current signals. The voltage doubler rectifier unit converts the high-frequency AC signal into a high-voltage DC signal; The voltage regulator unit converts the high-voltage DC signal into a DC bias voltage; The oscillation unit generates a low-frequency stimulation signal based on the DC bias voltage. After the output protection unit performs safe processing on the low-frequency stimulation signal, it is output to the target tissue by the stimulation electrode.

2. The wireless, battery-free electrical stimulation system according to claim 1, characterized in that, The receiving coil adopts a planar spiral structure with an inner diameter of 20 mm, 8 turns, and a line width and line spacing of 0.13 mm. The inductance is approximately 2.9 microhenries at the operating frequency.

3. The wireless, battery-free electrical stimulation system according to claim 1, characterized in that, The voltage doubler rectifier unit is composed of multiple diodes and multiple capacitors connected in a cascaded manner.

4. The wireless, battery-free electrical stimulation system according to claim 1, characterized in that, The voltage doubler rectifier unit is a four-stage voltage doubler rectifier circuit, which consists of four Schottky diodes D1, D2, D3, and D4 and four capacitors C1, C2, C3, and C4 connected in a cascaded manner.

5. A wireless, battery-free electrical stimulation system according to claim 1, characterized in that, The voltage regulation unit includes a low dropout linear regulator U1, an input filter capacitor C5, an output filter capacitor C6, resistors R1, R2, and R3; the low dropout linear regulator U1 has an input pin, a ground pin, an enable pin, an adjustment pin, and an output pin; The input pin is connected to the output terminal of the voltage doubler rectifier unit; the enable pin is connected to the output terminal of the voltage doubler rectifier unit; the adjustment pin is grounded through resistor R3, and resistor R2 is connected between the adjustment pin and the output pin; the output pin is connected to the input terminal of the subsequent oscillation unit; the input filter capacitor C5 is connected in parallel with resistor R1 and then connected between the input pin and ground; the output filter capacitor C6 is connected between the output pin and ground.

6. A wireless, battery-free electrical stimulation system according to claim 5, characterized in that, The output voltage of the voltage regulator unit is: ； in, R 2 represents the resistance value of resistor R2; R 3 represents the resistance value of resistor R3.

7. A wireless, battery-free electrical stimulation system according to claim 1, characterized in that, The oscillation unit includes a 555 timer U2, resistors R4, R5, and R6, capacitors C7, C8, and C9, and a Schottky diode D5; the 555 timer U2 has a ground pin, a trigger pin, an output pin, a reset pin, a control pin, a threshold pin, a discharge pin, and a power supply pin; The trigger pin is connected to the threshold pin and grounded through capacitor C7; the output pin is connected to the input terminal of the subsequent output protection unit; the reset pin is connected to the power supply pin and to the output terminal of the voltage regulator unit; the control pin is grounded through capacitor C8; the discharge pin is connected to the power supply pin through resistor R6; resistor R4 and Schottky diode D5 are connected in parallel between the trigger pin and the discharge pin; resistor R5 is connected between the output pin and the power supply pin; capacitor C9 is connected between the power supply pin and ground.

8. A wireless, battery-free electrical stimulation system according to claim 7, characterized in that, The frequency and duty cycle of the output voltage of the oscillation unit are as follows: ； ； in, R 4 represents the resistance value of resistor R4; R 6 represents the resistance value of resistor R6; C 7 represents the capacitance value of capacitor C7.

9. A wireless, battery-free electrical stimulation system according to claim 1, characterized in that, The output protection unit includes a protection resistor R7, a capacitor C10, a protection resistor R8, and a resistor R9; the capacitor C10, the protection resistor R8, and the resistor R9 form a high-pass filter to filter out the DC component in the output signal. The protective resistor R7, capacitor C10, and protective resistor R8 are connected in sequence to form a series branch; one end of the series branch is connected to the output terminal of the oscillation unit, and the other end is connected to the final output terminal of the wireless battery-free stimulator; the resistor R9 is connected between the final output terminal of the wireless battery-free stimulator and ground; stimulation electrodes are respectively set at the final output terminal and ground to output stimulation signals to the target tissue.

10. The application of the wireless battery-free electrical stimulation system according to any one of claims 1-9 in at least one of the fields of tissue wound repair, peripheral nerve injury treatment, and cardiac pacing.

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