Ear vagus nerve closed-loop regulation device and method based on composite vibration tactile stimulation

Abstract

The application discloses an ear vagus nerve closed-loop regulation and control device and method based on composite vibration tactile stimulation, and the device comprises a composite vibration execution mechanism, a conformal contact structure, a physiological signal monitoring and controller, a closed-loop feedback mechanism, a rhythm control strategy and HRV dynamic adjustment logic are arranged, an anatomical targeting design is adopted, balance between comfort, nerve specificity and individualized adaptation is achieved, stimulation effect and repeatability are improved, and use risk can be controlled under a multi-level safety strategy.

Description

Technical Field

[0001] This invention relates to the field of neuromodulation and wearable medical electronics technology, specifically to a closed-loop modulation device and method for the vagus nerve of the ear based on compound vibration tactile stimulation. Background Technology

[0002] Vagus nerve stimulation, as an important means of regulating the autonomic nervous system and multiple system functions, currently relies primarily on low-frequency electrical stimulation in clinical practice and research. This method depends on precise current control and a stable electrode-skin interface, placing high demands on electrode materials, contact pressure, and skin impedance. Improper control of current density, contact impedance, or driving waveform can easily lead to unpleasant sensations such as stinging, burning, and current noise, affecting tolerance and compliance. Furthermore, many existing protocols employ open-loop or semi-open-loop strategies, with fixed stimulation parameters or relying solely on manual adjustment, making it difficult to adaptively optimize according to changes in the subject's physiological state.

[0003] Modern neuroscience and clinical practice have shown that vibrational tactile stimulation can also act on the auricular branch of the vagus nerve in the ear, achieving a neuromodulation effect similar to electrical stimulation, while being more user-friendly in terms of comfort and safety. Vibration is less sensitive to electrical contact conditions, making it more suitable for long-term or home use. However, existing vibrational tactile solutions are mostly fixed outputs with a single frequency or a few frequencies, lacking closed-loop feedback based on objective indicators such as heart rate variability; the stimulation rhythm design is also relatively simplified, making it difficult to balance comfort and neurospecificity.

[0004] In summary, the existing technology has at least the following shortcomings: 1. Solutions that primarily use low-frequency electrical stimulation are highly sensitive to current and electrode conditions, resulting in poor comfort and electrical noise, which affects continuous wear and application scenarios.

[0005] 2. There is a general lack of closed-loop control based on physiological signals, making it difficult to adaptively adjust the stimulation frequency, amplitude and duty cycle according to the real-time status, resulting in insufficient individualization.

[0006] 3. Vibration tactile sensation often uses a single frequency or fixed rhythm, with limited neural coding dimensions, making it difficult to balance comfort and effective control depth.

[0007] Therefore, there is an urgent need for a vagus nerve modulation technique that combines vibrational tactile stimulation with closed-loop feedback. This technique can improve the comfort, specificity, and repeatability of stimulation through perceptible rhythmic control and HRV-based adaptive adjustment, and achieve individualized modulation within safe boundaries. Summary of the Invention

[0008] To overcome the problems of existing vagus nerve stimulation schemes, which mainly rely on low-frequency electrical stimulation, such as high sensitivity to current and electrode conditions, physical discomfort (stinging, current noise), and insufficient individualization and safety boundaries due to the use of open-loop or semi-open-loop methods, the present invention aims to provide a device and method for non-invasive closed-loop modulation of the vagus nerve in the ear based on composite vibration tactile stimulation. Through a closed-loop feedback mechanism, rhythm control strategy, HRV dynamic adjustment logic, and anatomical targeted design, a balance is achieved between comfort, nerve specificity, and individualized adaptation, improving stimulation effect and repeatability, and ensuring controllable use risks under multi-level safety strategies.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a closed-loop modulation device for the vagus nerve of the ear based on composite vibration tactile stimulation, comprising: A composite vibration actuator is used to output tactile composite vibration stimulation in the concha cavity and / or cymba conchae region of the subject's auricle; The conformal contact structure conforms to the curved surface of the region to form a stable mechanical coupling; A physiological signal monitoring module is used to collect heart rate and / or heart rate variability (HRV) related signals; The controller, electrically connected to the physiological signal monitoring module and the composite vibration actuator, is used to calculate the HRV frequency domain index and, based on the change in the LF / HF ratio, to perform closed-loop adaptive adjustment of at least one parameter of the vibration stimulus, including frequency, amplitude, duty cycle, and waveform. The composite vibration includes at least simultaneous or alternating stimulation of low-frequency and high-frequency bands, with the low-frequency band being 1–50 Hz and the high-frequency band being 50–500 Hz.

[0010] This invention also provides a method for closed-loop modulation of the vagus nerve in the ear based on composite vibrational tactile stimulation, comprising the following steps: S1: The contact structure of the stimulation end is attached and fixed to the concha cavity and / or cymba conchae; S2: Acquire physiological signals and calculate HRV frequency domain indices to obtain the LF / HF ratio; S3: Outputs a composite vibration stimulus that includes both low-frequency and high-frequency bands; S4: The vibration stimulation parameters are adjusted in a closed-loop adaptive manner based on the change in the LF / HF ratio; S5: Reduce stimulation intensity or stop stimulation when a preset safety condition is triggered.

[0011] Preferably, the composite vibration actuator may include a piezoelectric actuator, a mechanical amplification structure coupled thereto, and a flexible vibration-guiding contact layer to amplify the piezoelectric micro-displacement and transmit it to the ear tissue through the flexible layer; or a linear vibration motor (LRA) or a voice coil actuator may be used to achieve the composite output of the low-frequency and high-frequency bands.

[0012] Preferably, the system includes stimulation coding and rhythm: the stimulation waveform driven by the controller is a bidirectional square wave supplemented with a short-time sinusoidal transition; the time domain adopts pulse interval modulation (PIM), with 50 ms as the reference and the pulse interval being variable from 10 to 100 ms; the duty cycle of the composite vibration is allocated according to low frequency: high frequency = 80%: 20%, and allows fine adjustment within a range of no more than 20% above and below the reference value in closed-loop regulation.

[0013] Preferably, an HRV calculation and window are provided: the HRV calculation uses a 5-minute analysis window and updates in 1-minute increments; the LF band is 0.04–0.15 Hz, the HF band is 0.15–0.40 Hz, and the LF / HF ratio is used to measure the balance between sympathetic and parasympathetic responses and as a closed-loop feedback quantity.

[0014] Preferably, adaptive parameter tuning rules and boundaries are provided: when LF / HF changes by 0.25, the center frequencies of the low-frequency band and the high-frequency band are increased or decreased by 10% of their respective reference values; the overall output frequency is limited to 1–500 Hz, and the displacement amplitude is limited to 0.5 μm–0.5 mm.

[0015] Preferably, the contact structure is anatomically targeted and conforms geometrically to the concha cavity and / or cymba conchae surface, with a radius of curvature preferably of 4–10 mm and a contact area preferably of 250–350 mm². 2 It is fixed by at least one of ear loops, medical skin patches or elastic brackets to improve mechanical coupling stability and stimulation repeatability.

[0016] Preferably, a multi-level safety and medical attention prompt strategy is provided: when LF / HF ≥ 4 or the heart rate exceeds the preset range, the controller triggers a medical attention prompt and automatically reduces the stimulation amplitude until it stops; when LF / HF ≤ 1.5, the low-frequency center frequency f1 and the high-frequency center frequency f2 are kept unchanged, and the vibration intensity is reduced by 10% every 5 minutes until it is reduced to 50% of the initial intensity or the session ends; the vibration intensity includes at least one of amplitude or duty cycle.

[0017] Compared with the prior art, the present invention provides a closed-loop modulation device and method for the vagus nerve of the ear based on composite vibration tactile stimulation. The device includes a composite vibration actuator, a conformal contact structure, and a physiological signal monitoring and controller, and is based on the following core mechanisms: (1) Closed-loop feedback mechanism, with the ratio of LF to HF in HRV as the core feedback, and the parameter adaptive convergence is achieved by utilizing the directional change of HRV decrease during stimulation and recovery after stimulation is stopped; (2) Rhythm control strategy: Under the combined vibration of low frequency 1 to less than 50 Hz and high frequency 50 to 500 Hz, pulse interval modulation with 50 ms as the reference and interval of 10 to 100 ms is adopted. The waveform is mainly bidirectional square wave with short sine transition to take into account both comfort and nerve specificity. (3) HRV dynamic adjustment logic: when the ratio of LF to HF changes by 0.25, the low-frequency center frequency f1 and the high-frequency center frequency f2 are increased or decreased by 10% of the reference value respectively, and the stability and safety are improved by combining the threshold-triggered reduction and shutdown strategy. (4) Anatomically targeted design, conformal contact structure surface, preferably with a curvature radius of 4 to 10 mm and a contact area of ​​250 to 350 square millimeters, to enhance mechanical coupling and energy transfer consistency; This achieves a balance between comfort, neural specificity, and individualized adaptation, improving stimulation effectiveness and repeatability, while ensuring controllable risks under a multi-level safety strategy. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a block diagram of the device system structure provided in the embodiments of the present invention.

[0020] Figure 2 This is a flowchart of the method provided in an embodiment of the present invention.

[0021] Figure 3 This is an exploded view of the device structure provided in an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the device being worn according to an embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this 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. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0025] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figures 1 to 4 The image shows a preferred embodiment of the present invention.

[0027] Example 1: Overall Structure of the Device System Reference Figure 1 The device system provided in this embodiment adopts a modular architecture, mainly including a power supply module 160, a controller 140, a drive module 150, an actuator 110, a contact structure 120, a physiological signal monitoring module 130, a communication and human-computer interaction module 170, and a safety protection module 180.

[0028] The physiological signal monitoring module 130 is used to acquire physiological signals such as ECG / PPG and outputs heart rate and HRV correlation sequences for closed-loop control; the implementation method is as follows: Sensing methods: ECG (patch / silver chloride electrode) or PPG (infrared / green light), which can be used alone or in combination; Sampling and preprocessing: Sampling frequency ≥200 Hz, preferably 500 Hz; high pass 0.02 Hz, low pass 4 Hz, power frequency notch 50 / 60 Hz; data quality index (SQI) evaluation; RR interval extraction: The timing t of the R peak was obtained by detecting the R peak using Pan-Tompkins on ECG. n RR n =t n+1 -t n PPG pulse peak measurement; HRV frequency domain: After equal-interval resampling and detrending of the RR sequence, the power spectrum is estimated using FFT / Welch and integrated to obtain LF, HF and LF / HF.

[0029] Controller 140 is used to complete physiological signal reading and HRV frequency domain index calculation (LF / HF), generate composite vibration rhythm, and execute adaptive modulation and safety logic; the implementation method is as follows: Hardware: Low-power MCU / SoC (with built-in DSP / timer / ADC), communicating with peripherals via I / O. 2 C / SPI / UART / BLE connectivity; Algorithm: HRV calculation and state machine; adaptive parameter tuning (Δf=10% baseline, triggered by every 0.25 LF / HF change); duty cycle and amplitude gradient (ramp) to avoid abrupt changes; Stimulus encoding: PIM sequence generation; bidirectional square wave main morphology, with a short sinusoidal transition for comfort and resonance suppression.

[0030] The drive module 150 is used to convert control quantities into actuation drives, provide energy to the actuator 110, and send operating parameters such as voltage / current / temperature to the safety protection module 180; the implementation method is as follows: Piezoelectric solution: boost type high voltage drive (100–200 Vpp level), full bridge / half bridge output, overcurrent / overtemperature detection; LRA / Voice Coil Solution: Constant current / voltage drive, supports amplitude and frequency closed-loop; provides current / temperature / voltage monitoring data to the safety protection module 180; Interface: Control interface with controller 140 (PWM / DAC / I) 2 C); Status interface with protection module 180 (fault / ADC).

[0031] The composite vibration actuator 110 is used to output composite vibrations that are superimposed or alternate between low-frequency and high-frequency bands; the implementation method is as follows: Piezoelectric + Mechanical Amplification: Piezoelectric actuator (plate / stacked, rated displacement 1–20 μm) + spring-mass network consisting of springs / weights to achieve displacement amplification and frequency band shaping; Alternatives: Linear vibration motor (LRA) or voice coil actuator, which can also achieve a composite output of 1–50 Hz and 50–500 Hz.

[0032] Contact structure 120 is designed to conformally fit with the concha / cymene conchae cavity to achieve stable mechanical coupling and vibration transmission; the implementation method is as follows: Geometry and fit: Conforms to the conchae / cymene curvature, with a preferred radius of curvature of 4–10 mm and a preferred contact area of ​​250–350 mm². 2 The preferred contact pressure is 1–3 kPa.

[0033] Material layers: base layer (support component) + flexible vibration guiding layer (medical silicone / TPU, Shore A 20–40, thickness 0.5–1.5mm); or it can be integrally molded.

[0034] Function: The vibration of the composite vibration actuator 110 is stably coupled to the skin to improve the feel and reduce noise; the contact state can be determined by contact impedance / reflection acceleration or proximity sensing.

[0035] The communication and human-machine interaction 170 is used for bidirectional communication with the controller 140 for parameter setting, log uploading, firmware upgrades, and local prompts; the implementation method is as follows: Communication unit: BLE (optional Wi-Fi / NFC / USB), used for parameter sending, log uploading, and firmware upgrade; Local interaction: button / LED / buzzer or touch; bidirectional interaction with controller 140, not involved in closed-loop criteria.

[0036] The safety protection module 180 is used to monitor the drive module 150 (optionally, it also monitors the working status of the composite vibration actuator 110, triggers amplitude reduction / stop and records events); it can receive threshold settings from the controller 140; the implementation method is as follows: Monitoring objects: voltage / current / temperature / boost status / contact status / data quality from drive module 150 (and optional composite vibration actuator 110); Handling strategy: Issue a reduction / stop command to the drive module 150 according to the threshold or state machine; send the event and parameters back to the controller 140 for recording; the controller 140 can issue threshold configuration.

[0037] The power module 160 is used to provide system power and realize charging, discharging and protection. The implementation method is as follows: Power supply: Lithium battery + charging and protection; provides power to physiological signal monitoring module 130 / controller 140 / drive module 150 / communication and human-machine interaction 170 / composite vibration actuator 110, and provides overvoltage, overcurrent, overtemperature, undervoltage and short circuit protection; supports sleep / wake strategy to extend battery life.

[0038] The physiological signal monitoring module 130 collects physiological signals such as electrocardiogram / photoelectric signals and outputs them to the controller 140. The controller 140 generates a control quantity based on the calculated HRV index and sends it to the drive module 150. The drive module 150 drives the composite vibration actuator 110 to generate a low-frequency and high-frequency superimposed stimulus. The stimulus is transmitted to the human body through the mechanical coupling between the contact structure 120 and the ear tissue. The resulting physiological response (such as HR / HRV changes) is then collected and read back by the physiological signal monitoring module 130, thus forming a closed loop of "physiological signal monitoring module 130 → controller 140 → drive module 150 → composite vibration actuator 110 → contact structure 120 → physiological signal monitoring module 130". A bidirectional communication channel is established between the communication and human-machine interaction module 170 and the controller 140 for parameter setting, log uploading, and firmware upgrades; the safety protection module 180 receives voltage / current / temperature / contact status monitoring data from the drive module 150 (optionally also from the actuator 110), and issues a reduction or shutdown command to the drive module 150 when limits are exceeded; the power supply module 160 supplies power to the physiological signal monitoring module 130, controller 140, drive module 150, communication and human-machine interaction module 170, and composite vibration actuator 110.

[0039] Figure 1 The solid line represents the electrical / signal / control channel, while the dashed line represents mechanical coupling or physiological feedback formed through the human body / skin.

[0040] Specifically, the working process of this device includes the following steps: S101: Fitting: The contact structure 120 is conformally fitted to the concha cavity and / or concha cymba. After the contact detection is passed, the data acquisition begins. S102: Acquisition and Calculation: Physiological signal monitoring module 130 acquires ECG / PPG; controller 140 calculates LF / HF (LF 0.04–0.15 Hz, HF 0.15–0.40 Hz) in 5-minute analysis windows and 1-minute increments. S103: Output stimulus: The controller 140 generates a stimulus sequence based on PIM (reference interval 50 ms, pulse interval 10–100 ms variable), with the waveform mainly consisting of bidirectional square waves and supplemented by short-time sinusoidal transitions; the drive module 150 drives the composite vibration actuator 110 to output. S104: Closed-loop adaptive: When the LF / HF changes by 0.25, the controller 140 increases or decreases the low-frequency center f1 and the high-frequency center f2 by 10% of their reference values ​​respectively; the overall frequency is limited to 1–500 Hz, and the displacement amplitude is limited to 0.5 μm–0.5 mm; the duty cycle of low frequency: high frequency is preferably 80%:20%, with ±20% fine adjustment allowed; S105: Safety Strategy: If LF / HF ≥ 4 or heart rate exceeds the limit, the safety protection module 180 triggers a health alert / medical advice and the drive module 150 executes a reduction in intensity until shutdown; if LF / HF ≤ 1.5, keep f1 and f2 unchanged, and reduce the stimulation intensity by 10% every 5 minutes until it drops to 50% of the initial intensity or ends; if overheating / overcurrent / pressure rise abnormalities, insufficient data quality, or contact loss occur, the safety protection module 180 immediately commands the drive module 150 to stop stimulation and record the event; S106: Communication and Recording: Communication and Human-Machine Interaction 170 interacts bidirectionally with Controller 140 to complete mode selection, parameter distribution, log upload and firmware upgrade.

[0041] Example 2: Implementation of Rhythm Control and Closed-Loop Algorithm This embodiment operates on the device system of Embodiment 1. The physiological signal monitoring module 130 provides raw ECG / PPG data and heart rate; the controller 140 completes the calculation of HRV index and generation of stimulation rhythm, and sends the control quantity to the drive module 150 to drive the composite vibration actuator 110; the composite vibration actuator 110 applies mechanical stimulation to the concha / cymene via the contact structure 120 to induce physiological feedback, and the physiological signal monitoring module 130 reads back to form a closed loop; the safety protection module 180 monitors the voltage / current / temperature / contact status of the drive module 150 (optional and the composite vibration actuator 110), and executes amplitude reduction / shutdown through the drive module 150 when the limit is exceeded.

[0042] Specifically, the stimulation rhythm and encoding are implemented as follows: 1. Dual-frequency composite: The output includes at least simultaneous or alternating stimulation of the low-frequency band 1–50 Hz and the high-frequency band 50–500 Hz; the duty cycle allocation is preferably low frequency: high frequency = 80%: 20%, and ±20% fine adjustment is allowed within the closed loop; 2. Waveform and time-domain coding: The main waveform is a bidirectional square wave, supplemented by a short-time sine transition; the time domain uses pulse interval modulation (PIM), with a reference interval of 50 ms and a pulse interval that can vary from 10 to 100 ms. 3. Parameter definitions: Low-frequency center f1, high-frequency center f2, amplitude / displacement A, duty cycle D, waveform type W (square wave / sine transition), PIM reference T0; 4. Preset modes (user-selected, closed-loop only parameter layer adaptive, no automatic model switching) include the following methods: Relaxation: f1=25 Hz, f2=500 Hz, D=80%:20%; Analgesia: f1=1 Hz, f2=350 Hz, superimposed with short-duration high-frequency pulses; Sleep aid: f1 alternates slowly between 4–20 Hz, f2 = 350 Hz.

[0043] Specifically, the HRV calculation and feedback are implemented as follows: 1. Sampling and preprocessing: Sampling frequency ≥200 Hz, preferably 500 Hz; high pass 0.02 Hz, low pass 4 Hz, power frequency notch 50 / 60 Hz; filtered according to data quality index (SQI); 2. RR Interval Extraction: The R peak time t was obtained from the ECG using Pan-Tompkins. n RR n =t n+1 -t n PPG is used as a pulse peak replacement. 3. Window and Update: Analyze the window for 5 minutes, slide the step for 1 minute, and update the results every 1 minute; 4. Frequency domain parameters: After equal-interval resampling and detrending, the power spectrum is estimated using FFT / Welch. The power is obtained by integration: LF = 0.04–0.15 Hz and HF = 0.15–0.40 Hz. LF / HF is taken as the closed-loop feedback quantity.

[0044] The closed-loop adaptive parameter tuning rule is implemented as follows: 1. Frequency stepping: When LF / HF changes by 0.25, f1 and f2 are increased or decreased by 10% of their reference values ​​respectively. LF / HF increases → f1, f2 + Δf; LF / HF decreases → f1, f2 - Δf.

[0045] The definition and value rules for Δf are as follows: • Δf is the frequency step increment (in Hz) for each parameter update.

[0046] • For the low-frequency center f1: Δf1 = 0.1 × f1_ref; For the high-frequency center f2: Δf2 = 0.1 × f2_ref.

[0047] • f1_ref and f2_ref are the base center frequencies at the start of this session (i.e., the user-selected preset mode or the initial settings f1 and f2).

[0048] • Trigger and Direction: Compared to the previous update, each change of 0.25 in LF / HF counts as one increment. Ascending: f1 ← f1 + Δf1, f2 ← f2 + Δf2; Decrease: f1 ← f1 - Δf1, f2 ← f2 - Δf2. If |Δ(LF / HF)| ≥ 0.25×n, then adjust cumulatively by n levels.

[0049] • Boundaries and resolution: After adjustment, f1 and f2 are limited to 1–50 Hz and 50–500 Hz respectively; the frequency can be rounded to 0.1 Hz according to the system resolution (or the actual DAC / timer resolution).

[0050] For example: if the reference f1_ref = 20 Hz and f2_ref = 400 Hz, then Δf1 = 2 Hz and Δf2 = 40 Hz. If LF / HF increases by 0.50 compared to the previous value, then f1 and f2 are each adjusted up by 2 levels: f1 → 24 Hz and f2 → 480 Hz (the boundary value is taken when the upper limit is exceeded). 2. Boundary Limitations: Overall output frequency is limited to 1–500 Hz; displacement / amplitude is limited to 0.5 μm–0.5 mm; duty cycle is finely adjusted within ±20% around 80%:20%; 3. Smoothing and anti-oscillation: Parameter updates use a linear ramp transition (e.g., 0.5–2 s), and a small dead zone can be set to avoid frequent jitter (optional).

[0051] Example 3: Device Structure and Assembly Method like Figure 3 As shown, this device adopts a layered assembly structure, wherein: • Housing assembly 190: includes ear hooks 190-1, upper shell 190-2, lower shell 190-3, sealing ring 190-4, fasteners 190-5, and optional connecting end shell 190-6 and left symmetrical shell 190-7; the shell material can be PC+ABS or PA12, with a sweat-resistant coating on the surface, and the sealing ring is made of silicone. • Contact structure 120 and flexible vibration-guiding contact layer 114: The two can be bonded separately or molded as one piece, preferably medical silicone / TPU, Shore A20–40, thickness 0.5–1.5 mm, used to conformally bond with the concha / cymene to form a stable mechanical coupling; • Mechanical amplification structure 113: A spring-mass network formed by spring 113-1 and weight 113-2, used for displacement amplification and frequency band shaping; • Piezoelectric actuator 111, linear / voice coil actuator 112: Piezoelectric actuator 111 can be a piezoelectric actuator (plate type / stacked type), and linear / voice coil actuator 112 can be a linear vibration motor / voice coil actuator. • Control board 130-1: includes an electrically connected physiological signal monitoring module 130, controller 140, drive module 150, power supply module 160, and temperature / safety sensor for monitoring temperature rise and abnormalities; • Wire / Interface 170-1: For communication / power supply leads, equipped with stress relief and waterproofing; • The composite vibration actuator 110 includes a piezoelectric actuator 111, a linear / voice coil actuator 112, and a mechanical amplification structure 113 coupled thereto (spring 113-1, weight 113-2). Its output is transmitted to the contact end via a connecting rod / flange, and is mechanically coupled with the contact structure 120 and its skin-side flexible vibration-guided contact layer 114 to achieve composite vibration stimulation.

[0052] The key dimensions, tolerances, and process windows for the main components are as follows: • Adhesive layer thickness: The adhesive layer between the flexible vibration-guiding contact layer 114 and the contact structure 120 is 0.10–0.30 mm (±0.05 mm) to ensure flexibility and energy transfer; • Coaxial / Concentric: The coaxiality of the piezoelectric actuator 111, linear / voice coil actuator 112 and mechanical amplification structure 113 is ≤0.2 mm, ensuring resonance consistency and low noise; • Clearance and limit: The minimum clearance between the end of the piezoelectric actuator 111 and the inner wall of the housing is ≥0.5 mm; the height tolerance of the limit post is ±0.05 mm; • Tightening torque: Tighten fasteners 190-5 to 0.25–0.35 N·m to avoid warping and noise; • Thermal pad: 0.5–1.0 mm thick, thermal conductivity 1–3 W / m·K, covering the drive heat source and the housing heat sink; • Antenna avoidance: The RF antenna should be kept 3–5 mm away from metal parts.

[0053] The assembly process and process control steps are as follows: S301: Sub-component preparation: Incoming material inspection (dimensions, appearance, functional point measurement), FPC bending radius ≥ 6 mm; Plasma / alcohol treatment of bonding surfaces; S302: Actuator-Amplification Structure Assembly: Fix the piezoelectric actuator 111 / linear / voice coil actuator 112 to the mounting position of the mechanical amplification structure 113, calibrate the coaxiality and set the preload (0.1–0.5 mm); apply adhesive for fixing, initial curing ≥30 min; S303: Vibration guiding layer bonding: Bond the flexible vibration guiding contact layer 114 to the skin side of the contact structure 120, control the adhesive layer thickness to 0.1–0.3 mm, scrape and remove bubbles; cure at room temperature for 24 h or accelerate curing at 60°C for 2 h; S304: Mechanical assembly assembly: Couple the mechanical amplification structure 113 assembly with the contact structure 120 / flexible vibration guiding contact layer 114, check the free travel and limit, and confirm that there is no interference or abnormal noise; S305: Control board installation: Assemble the control board 130-1 and lead out the electrode / optical components, aligning the housing window; complete the open / short circuit and SQI self-test; S306: Control / Drive and Power Stacking: Assemble controller 140 / drive module 150 and power module 160, board-to-board mating or FPC soldering; power-on communication test, DFU channel check; S307: Safety sensor layout: The safety protection module 180 is placed close to the heat source / drive area, and the thermal pad is pressed together; the threshold configuration is written into the controller 140; S308: Wiring Harness and Waterproofing: Introduce 170-1 wires / interfaces, complete stress relief + waterproof cable sleeve; organize the wiring harness to avoid moving parts; S309: Housing and Sealing: Place the component into the lower housing 190-3, lay the sealing ring 190-4, close the upper housing 190-2, and tighten the fastener 190-5 with a pressure of 0.25–0.35 N·m; assemble the ear hook 190-1.

[0054] S310: Functional Verification: o Vibration output: Displacement / acceleration meets standards (dual frequency band); o Closed loop: Real-time calculation and step parameter tuning (0.25→10%) of LF / HF are effective; o Safety: Over-temperature / over-current / abnormal voltage rise triggers throttling / shutdown; o Communication: BLE pairing, log upload and firmware upgrade; o Sealing: IPX4 / 5 splash test; S311: Aging and Release: Typical 2–4 h temperature cycling / vibration aging; record events and parameter logs, and put into storage if qualified.

[0055] Example 4: Usage Method This embodiment operates based on the device described in Embodiment 1, and refers to... Figure 2 The method includes the following steps.

[0056] S1: Fitting and fixing The contact structure of the stimulation end is attached and fixed to the concha cavity and / or cymba conchae to form a stable mechanical coupling between the flexible vibration-guiding contact layer and the skin; after the adequacy of the attachment is checked, the collection stage begins. S2: Data Acquisition and HRV Calculation Physiological signals were acquired and HRV frequency domain indices were calculated to obtain LF and HF and their ratio LF / HF. A five-minute analysis window with one-minute update increments was preferred, with the LF band at 0.04–0.15 Hz and the HF band at 0.15–0.40 Hz. S3: Composite vibration output The output contains composite vibrational stimulation that simultaneously or alternately includes low-frequency and high-frequency bands, with the low-frequency band ranging from 1 to 50 Hz and the high-frequency band from 50 to 500 Hz. Preferably, a bidirectional square wave is used as the main component, supplemented by a short-time sinusoidal transition. In the time domain, pulse interval modulation is used to generate a stimulation sequence with a base of 50 milliseconds and a variable range of 10 to 100 milliseconds. The duty cycle of the low-frequency and high-frequency bands is initially allocated at a ratio of 80 to 20. S4: Closed-loop adaptive adjustment Based on the change in the LF / HF ratio, at least one parameter of the vibration stimulus is adaptively adjusted in a closed loop. This parameter includes at least one of frequency, amplitude, duty cycle, or waveform. Preferably, when the LF / HF ratio changes by 0.25, the low-frequency center frequency and the high-frequency center frequency are increased or decreased in steps of 10% of their reference values, respectively, and the overall output frequency is limited to 1 to 500 Hz, and the displacement amplitude is limited to the range of 0.5 micrometers to 0.5 millimeters. The parameter updates are performed using a ramp-like smooth transition. S5: Safety Handling The system automatically reduces the stimulation intensity or stops stimulation when preset safety conditions are triggered. Preferably, when the ratio of LF to HF reaches four or higher, or the heart rate exceeds a preset range, the system triggers a medical prompt and executes a strategy of reducing the intensity until shutdown; when the ratio of LF to HF is not higher than 1.5, the low-frequency and high-frequency center frequencies remain unchanged, and the stimulation intensity is reduced by 10% every five minutes until it is reduced to 50% of the initial intensity or the session ends; when overheating, overcurrent, abnormal pressure rise, insufficient data quality, or loss of contact is detected, the system immediately shuts down and records the event.

[0057] Example 5: Anatomical Targeting and Conformal Fitting Reference Figure 3 and Figure 4 To improve the nerve specificity and comfort of the stimulation, this embodiment optimizes the geometry, materials, and fit detection of the contact end: • Curvature and area: Based on three-dimensional scanning and finite element simulation of the auricle, the radius of curvature of the concha is preferably 4–6 mm, and that of the cymba conchae is preferably 5–10 mm; the overall radius of curvature of the contact structure 120 is preferably 4–10 mm; and the contact area is 250–350 mm². 2 The preferred contact pressure is 1–3 kPa.

[0058] • Material layering: The contact end consists of a rigid contact structure 120 and a flexible vibration-guiding contact layer 114 on its skin side. The flexible vibration-guiding contact layer 114 is made of medical-grade silicone or TPU, Shore A 20–40, with a thickness of 0.5–1.5 mm; the contact structure 120 is made of PC / ABS or PA12. The two can be integrally molded or bonded separately, with an adhesive layer thickness of 0.10–0.30 mm.

[0059] • Positioning and reproducibility: Positioning protrusions, grooves or guide edges are set on the outer shape of the contact structure 120 to correspond to the anatomical benchmark of the auricle, reducing daily wearing deviations.

[0060] Specifically, the method for testing fit adequacy is as follows: • Contact impedance method: A weak test signal is injected into the contact surface. If the impedance is lower than the threshold, the fit is considered sufficient.

[0061] • Reflection acceleration method: The actuator outputs a very low intensity test vibration, and the micro-acceleration response at the contact end is read. The amplitude and phase difference meet the model threshold to determine that the fit is sufficient.

[0062] • Proximity / Optical Method: A low-power proximity sensor or a light-transmitting window is arranged on the contact surface side, and the fit is determined when the threshold is reached.

[0063] If the fit is insufficient, the controller 140 blocks the stimulation and prompts the user to reset via communication with the human-computer interaction 170.

[0064] This structure significantly improves mechanical coupling stability and high-frequency component transmission efficiency without increasing user pressure, thereby enhancing the consistency of amplitude and frequency response of dual-frequency composite stimulation in the concha / cymene, which is beneficial to the repeatability of closed loop.

[0065] Example 6: Security and Fault Tolerance Strategies The safety protection module 180 continuously monitors: drive output voltage / current, actuator and drive board temperature, boost status, contact status, data quality (SQI), power supply voltage, and communication link. The optimal sampling period is 10–100 ms, with asynchronous polling for each item.

[0066] The state machine and threshold settings are as follows: Physiological thresholds: When LF / HF ≥ 4 or heart rate exceeds the limit (e.g., <45 bpm or >120 bpm), enter health alarm state, execute the "reduce intensity → stop" sequence, and provide medical advice through communication and human-computer interaction 170; when LF / HF ≤ 1.5, keep f1 and f2 unchanged, reduce intensity by 10% every 5 minutes until the initial 50% or the session ends; • Hardware thresholds (example values, calibrable): Skin-side equivalent temperature > 42–45°C; Driver board hotspot > 85–95°C; Boost deviation > Set value ±10%; Abnormal drive current > 150% of rated; Battery undervoltage < 3.0 V. Immediately stop the machine and log the event if any limit is exceeded. • Data and contact anomalies: If the SQI is below the threshold, contact is lost, or communication is interrupted, and more than two retries are made, a safe shutdown will be initiated.

[0067] Furthermore, it records timestamps, patterns, f1 / f2 ratios, duty cycles, intensity, peak displacement estimates, LF / HF ratios, heart rate, and event codes. The recovery strategy follows the principle of "manual confirmation first, automatic recovery cautious": non-fatal alarms can be restarted at low intensity after conditions are restored; fatal alarms require manual confirmation or termination of the session.

[0068] Example 7: Preset Mode and Time Series Users select a preset mode through communication and human-computer interaction (170). The closed loop only adapts at the parameter level and does not automatically switch modes. The mode definition is as follows: • Relaxed mode: f1=25 Hz, f2=500 Hz; duty cycle: low frequency: high frequency 80%:20%; PIM reference interval 50ms.

[0069] • Analgesia mode: f1=1 Hz, f2=350 Hz; a short pulse envelope is superimposed on the high-frequency window for short-term analgesia.

[0070] • Sleep aid mode: f1 slowly alternates in the 4–20 Hz range, f2=350 Hz, with a lower overall intensity.

[0071] The time series and ramp settings are as follows: Each session lasts 10–30 minutes; both the start and end use a linear ramp of 0.5–2 seconds to avoid sudden changes in user experience; pause during the session by pressing “slow descent → stop” and resume by pressing “slow ascent”.

[0072] The operating parameters and display settings are as follows: It displays LF / HF, heart rate, f1 / f2, intensity, and remaining duration in real time; users can fine-tune comfort within safe boundaries, and the parameters are constrained in a closed loop according to the scope of the dependent claims.

[0073] Example 8: Alternatives to Actuators and Drives 1. Piezoelectric + Mechanical Amplification Scheme Piezoelectric actuator 111: Plate or stacked piezoelectric, rated displacement 1–20 μm.

[0074] Mechanical Amplifier 113: Spring 113-1 and weight 113-2 form a spring-mass network for displacement amplification and frequency band shaping.

[0075] Drive Module 150: Boost type high voltage drive, typically 100–200 Vpp, full bridge / half bridge output, with overcurrent / overtemperature detection.

[0076] Advantages: Wide high-frequency response, low noise; pay attention to insulation and moisture protection.

[0077] 2. Linear vibration motor / voice coil solution Linear / voice coil actuator 112: LRA or voice coil, easy to drive, with a large stroke.

[0078] Drive module 150: constant voltage / constant current drive, supports current readback and temperature monitoring.

[0079] Advantages: Simple structure, sufficient low-frequency energy; attention should be paid to avoiding mechanical noise and resonance.

[0080] 3. General Measures Noise suppression: A damping ring / microporous foam is added between the contact structure 120 and the housing; the waveform edge adopts a short-time sinusoidal transition.

[0081] Thermal management: A thermal pad of 1–3 W·m is laid between the actuator 110 / drive module 150 and the housing. -1 ·K -1 The safety protection module 180 monitors the temperature rise and triggers a temperature reduction / shutdown.

[0082] Interface compatibility: The two actuation schemes are interchangeable through the same mechanical mounting reference and electrical connection definition, without changing the appearance or user experience.

[0083] Example 9: Communication and Human-Computer Interaction 1. Communication Scheme • Protocol: BLE preferred (Wi-Fi / NFC / USB optional).

[0084] • Functions: Parameter distribution, log / event upload, firmware upgrade DFU, clock synchronization.

[0085] • Fault tolerance: If the link is lost, it will retry twice. If it fails, it will maintain the current safe state and provide a notification.

[0086] 2. Human-computer interface • Local: Display session status and alarms via button / LED / buzzer or touch.

[0087] • Application side: Displays real-time LF / HF, heart rate, f1 / f2, and intensity; provides mode selection and session report export; upgrades include verification and rollback capabilities.

[0088] 3. Data Minimization and Storage Only data items necessary for closed-loop operation and traceability are recorded, and a circular buffer and power-off retention are employed; users can export or delete historical records.

[0089] Example 10: Calibration and Personalized Adaptation 1. Initial Calibration For the first time, an individual LF / HF baseline is established using a resting period of 2–5 min; the initial values ​​of the session are the selected mode parameters f1_ref, f2_ref, and the initial intensity.

[0090] 2. In-session adaptation Each change of 0.25 in LF / HF is recorded as a increment, and f1 and f2 are increased or decreased in steps of 10% of their reference values ​​respectively; the total frequency is constrained to 1–500 Hz, and the displacement / amplitude is 0.5 μm–0.5 mm; the duty cycle is finely adjusted within ±20% around 80%:20%; a 0.5–2 s ramp is used, and a small dead zone is set when necessary to suppress frequent jitter.

[0091] 3. Cross-session individualization Save individual characteristic parameters (f1 / f2, comfort level, typical LF / HF range and alarm records) as initial values ​​for the next session; if subjective discomfort or abnormal LF / HF surge occurs, automatically revert to one level and prompt for a check of fit or switch to a gentler mode.

[0092] 4. Termination and Reporting A report is generated after the session ends: f1 / f2 time series, intensity curve, LF / HF and heart rate trajectory, event code and compliance summary, for clinical or self-management reference.

[0093] Example 11: Manufacturing Tolerances and Assembly Process Window To ensure consistent vibration output and long-term reliability, this embodiment provides key tolerances and process windows: 1. Adhesion and curing: The adhesive layer thickness between the flexible vibration-guided contact 114 and the contact structure 120 is 0.10–0.30 mm (±0.05 mm); room temperature curing ≥24 h or accelerated curing at 60 °C × 2 h.

[0094] 2. Coaxiality / Concentricity: The coaxiality of the piezoelectric actuator 111, the linear / voice coil actuator 112 and the mechanical amplification structure 113 is ≤0.20 mm; the axial runout between the contact end and the housing is ≤0.15 mm.

[0095] 3. Gap / Limit: The minimum gap between the end of the piezoelectric actuator 111 and the inner wall of the housing is ≥0.5 mm; the height tolerance of the limit post is ±0.05 mm.

[0096] 4. Tightening torque: 0.25–0.35 N·m for fastener 190-5; anti-loosening coating optional.

[0097] 5. FPC and wiring: Minimum bending radius ≥6–8 mm; limit / foam support for vibration zones.

[0098] 6. Thermal conductivity and shielding: Thermal conductive patch thickness 0.5–1.0 mm, thermal conductivity 1–3 W·m -1 ·K -1 Grounding / shielding points are reserved inside the housing, and the distance between the antenna and the metal parts is ≥3–5 mm.

[0099] 7. Factory verification: Displacement / acceleration frequency response meets standards; Closed-loop “0.25 step → 10% frequency step” is effective; Over-temperature / over-current / under-voltage / voltage rise abnormalities and contact / SQI abnormalities can all trigger safety shutdown; IPX4 / 5 water splash test passed; Re-inspection passed after 2-4 hours of aging with temperature cycling / vibration.

[0100] Note: The above is the preferred window, and equivalent replacements are allowed within the scope of not affecting performance and security.

[0101] Example 12: Power and Battery Life Management Power module 160 provides power to the system and implements multiple protections and power consumption management: 1. Power supply structure: lithium battery cell + charging / protection board; provides overcharge, over-discharge, overcurrent, short circuit and temperature protection, undervoltage threshold (example) ≈ 3.0 V.

[0102] 2. Power consumption strategy: idle sleep and timed wake-up; adaptive communication broadcast interval; start / stop / intensity adjustment adopts a 0.5–2 s ramp to reduce surge and thermal shock.

[0103] 3. Monitoring and feedback: Voltage / current / temperature and remaining power are reported to controller 140; it is linked with safety protection module 180 to reduce speed / stop the machine if the limit is exceeded.

[0104] 4. Battery life example: In relaxation / sleep mode (medium intensity, 10–30 min / cycle), typical battery life is 6–12 h (depending on the type and intensity of piezoelectric actuator 111 and linear / voice coil actuator 112).

[0105] 5. Charging / DFU: Supports wired or dock charging; performs firmware upgrades (DFU) via communication and human-machine interaction 170, with verification and rollback capabilities.

[0106] 6. Environment and Reliability: Operates at normal temperature, meets IPX4 / 5 requirements in sweat / splash scenarios; temperature rise is controlled by the 180°C threshold of the safety protection module, and if triggered, the temperature will be reduced or the system will be shut down and the data will be logged.

[0107] In summary, the present invention provides a closed-loop modulation device and method for the vagus nerve of the ear based on composite vibration tactile stimulation, which establishes the following core mechanism: (1) Closed-loop feedback mechanism, with the ratio of LF to HF in HRV as the core feedback, and the parameter adaptive convergence is achieved by utilizing the directional change of HRV decrease during stimulation and recovery after stimulation is stopped; (2) Rhythm control strategy: Under the combined vibration of low frequency 1 to less than 50 Hz and high frequency 50 to 500 Hz, pulse interval modulation with 50 ms as the reference and interval of 10 to 100 ms is adopted. The waveform is mainly bidirectional square wave with short sine transition to take into account both comfort and nerve specificity. (3) HRV dynamic adjustment logic: when the ratio of LF to HF changes by 0.25, the low-frequency center frequency f1 and the high-frequency center frequency f2 are increased or decreased by 10% of the reference value respectively, and the stability and safety are improved by combining the threshold-triggered reduction and shutdown strategy. (4) Anatomically targeted design, conformal contact structure surface, preferably with a curvature radius of 4 to 10 mm and a contact area of ​​250 to 350 square millimeters, to enhance mechanical coupling and energy transfer consistency; This achieves a balance between comfort, neural specificity, and individualized adaptation, improving stimulation effectiveness and repeatability, while ensuring controllable risks under a multi-level safety strategy.

[0108] The embodiments of the present invention have been described in detail above, but the invention is not limited to these embodiments. Those skilled in the art can make many equivalent modifications or substitutions without departing from the spirit of the invention, and these equivalent modifications or substitutions are all included within the protection scope defined by the claims of this application.

Claims

1. A closed-loop modulation device for the vagus nerve of the ear based on composite vibration tactile stimulation, characterized in that, Mainly includes: A composite vibration actuator is used to output tactile composite vibration stimulation in the concha cavity and / or cymba conchae region of the subject's auricle; A conformal contact structure is used to form a stable mechanical coupling in the region; Physiological signal monitoring module, used to collect heart rate and / or heart rate variability (HRV) related signals; The controller is electrically connected to the physiological signal monitoring module and the composite vibration actuator. The controller is used to calculate the HRV frequency domain index and, based on the change of the LF / HF ratio, to perform closed-loop adaptive adjustment of at least one parameter of the vibration stimulus. The parameter includes frequency, amplitude, duty cycle and / or waveform. The composite vibration includes at least simultaneous or alternating stimulation of low-frequency and high-frequency bands.

2. A closed-loop modulation method for the vagus nerve of the ear based on composite vibrational tactile stimulation, characterized in that, Includes the following steps: S1: The contact structure of the stimulation end is attached and fixed to the concha cavity and / or concha cymba; S2: Acquire physiological signals and calculate HRV frequency domain indices to obtain the LF / HF ratio; S3: Outputs a composite vibration stimulus that includes both low-frequency and high-frequency bands; S4: The vibration stimulation parameters are adaptively adjusted in a closed loop based on the change in the LF / HF ratio; S5: Reduce stimulation intensity or stop stimulation when a preset safety condition is triggered.

3. The apparatus according to claim 1, characterized in that, The composite vibration actuator includes a piezoelectric actuator, a mechanical amplification structure coupled thereto, and a flexible vibration-guiding contact layer, to amplify the piezoelectric micro-displacement and transmit it to the ear tissue through the flexible layer.

4. The apparatus according to claim 1, characterized in that, The composite vibration actuator can alternatively employ a linear vibration motor or a voice coil actuator to achieve the composite output of the low-frequency and high-frequency bands.

5. The apparatus according to claim 1, characterized in that, The controller drives a bidirectional square wave with a short-duration sine transition, and in the time domain, it uses pulse interval modulation (PIM) to generate a stimulation sequence with a base of 50 ms and a pulse interval of 10–100 ms.

6. The apparatus according to claim 1, characterized in that, The duty cycle of the composite vibration is allocated in a ratio of 80% for low frequency band to 20% for high frequency band, and fine-tuning within ±20% is allowed in closed-loop regulation.

7. The method according to claim 2, characterized in that, HRV calculations use a 5-minute analysis window and are updated in 1-minute increments. The LF band is 0.04–0.15 Hz and the HF band is 0.15–0.40 Hz. The LF / HF ratio is used to measure the balance between sympathetic and parasympathetic responses.

8. The method according to claim 2, characterized in that, The adaptive parameter tuning rule is as follows: when the LF / HF changes by 0.25, the center frequencies of the low-frequency band and the high-frequency band are increased or decreased by 10% of the reference value, respectively, and the overall output frequency is limited to 1–500 Hz and the displacement amplitude is limited to 0.5 μm–0.5 mm.

9. The apparatus according to claim 1, characterized in that, The contact structure is geometrically conformal to the conchae cavity / cymene curvature, with a preferred radius of curvature of 4–10 mm and a preferred contact area of ​​250–350 mm². 2 It is secured by at least one of ear loops, medical skin patches, or elastic supports.

10. The apparatus or method according to claim 1 or 2, characterized in that, The system is configured with a multi-level safety and medical alert strategy, including: when the ratio of LF to HF reaches 4 or higher, or when the heart rate exceeds a preset range, the controller triggers a medical alert and automatically reduces the stimulation amplitude until it stops; when the ratio of LF to HF is not higher than 1.5, the low-frequency center frequency f1 and the high-frequency center frequency f2 are kept constant, and the vibration intensity is reduced by 10% every 5 minutes until it is reduced to 50% of the initial intensity or the session ends, wherein the vibration intensity includes at least one of amplitude or duty cycle.

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