A closed-loop sleep-aiding method based on transcranial static magnetic field and alternating current stimulation collaborative intervention

Abstract

The application discloses a closed-loop sleep-aiding method based on transcranial static magnetic field and alternating current stimulation synergistic intervention, and belongs to the technical field of sleep induction. The method disclosed by the application firstly utilizes tSMS to promote cortical neuron membrane potential hyperpolarization and reduce the cortical excitability baseline; then quantifies the cortical state through real-time EEG brain electrical signal diagram, and accurately captures the physiological critical window of high-frequency background brain electrical signal recession caused by hyperpolarization; finally, automatically triggers low-frequency and weak-intensity tACS intervention in the window period, and realizes efficient phase locking to low-frequency sleep rhythm. The method disclosed by the application realizes efficient, accurate and side-effect-free closed-loop intervention on sleep difficulty.

Description

Technical Field

[0001] This invention belongs to the field of sleep induction technology, specifically relating to a closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation. Background Technology

[0002] In recent years, sleep disorders, particularly difficulty falling asleep, have become increasingly prevalent worldwide. From a neurophysiological perspective, the initiation of natural sleep depends on a fundamental shift in the state of the thalamus-cortex network: widespread hyperpolarization of cortical neurons (releasing the inactivation of T-type calcium channels), subsequently generating and maintaining low-frequency synchronized rhythms such as sleep spindles and slow waves. However, the cerebral cortex of patients with difficulty falling asleep is often in a state of "over-arousal," with high levels of neuronal depolarization, exhibiting dense, high-frequency, asynchronous brain electrical activity such as beta waves and gamma waves. This persistent high-frequency background may hinder the brain's spontaneous evolution towards low-frequency synchronized rhythms (such as sleep slow waves and spindles), and is the core pathological mechanism leading to insomnia.

[0003] Currently, non-invasive neuromodulation techniques are used for sleep intervention, especially transcranial alternating current stimulation (tACS), which induces sleep by introducing weak, low-frequency alternating currents (such as slow-wave rhythms of 0.5-4 Hz) into the scalp through a rhythm-entraining mechanism. However, existing single tACS techniques face the dilemma of severe state dependence and stimulation side effects in practical applications, making it difficult to achieve stable and efficient sleep regulation. Specifically, ① existing tACS sleep aid devices attempt to forcibly induce low-frequency sleep rhythms in the highly excited and desynchronized cerebral cortex of insomnia patients. This violates the hyperpolarization prerequisite required to generate slow waves, causing the weak alternating current to be completely submerged by the high-frequency background EEG activity, resulting in extremely low traction efficiency; ② Attempts to cross the skull barrier and forcibly suppress high-frequency EEG by increasing the tACS current intensity will inevitably trigger the alarm system of scalp pain and visual nerves, activating the brainstem reticular formation, which will exacerbate the patient's anxiety and defensive arousal, completely destroying the sensory blocking environment required for falling asleep; ③ Sleep regulation requires not only frequency matching but also physiological condition matching, which cannot be met simultaneously by a single tACS technology. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation.

[0005] The technical problem addressed by this invention is solved as follows:

[0006] A closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation is realized using a coaxial confocal magnetoelectric composite array and a central control unit. The coaxial confocal magnetoelectric composite array includes a permanent magnet, a ring-shaped conductive component, and miniature flexible dry electrode probes. The permanent magnet is located at the center, is cylindrical, and has an insulating, skin-friendly coating on its outer surface. Ring-shaped conductive electrodes are concentrically nested around the permanent magnet. Several miniature flexible dry electrode probes are embedded on the outer edge of the ring-shaped conductive component, used for real-time acquisition of EEG signals and driving the ring-shaped conductive component. The central control unit is used to calculate the cortical arousal index of the EEG signal in real time, set a dynamic trigger threshold, determine the physiological critical window based on the cortical arousal index and the dynamic trigger threshold, and then control the ring-shaped conductive component to generate alternating current. The process is as follows:

[0007] Step 1: Perform passive magnetic pre-inhibition to reshape the basic electrophysiological state of the cortex;

[0008] The permanent magnets in the coaxial and confocal magnetoelectric composite array generate a constant static magnetic field that acts on the designated target area;

[0009] Step 2: Real-time quantification of cortical state and dynamic optimization of physiological critical window;

[0010] The central control unit performs frequency domain power integration over a continuous sliding time window to calculate the cortical arousal index ArI in real time. It sets a dynamic trigger threshold using the cortical arousal index ArI within the initial set time period of passive magnetic pre-inhibition. The real-time cortical arousal index ArI is compared with the dynamic trigger threshold. If the real-time cortical arousal index ArI is less than the dynamic trigger threshold within several consecutive sliding time windows, it is determined that the physiological critical window has been reached.

[0011] Step 3: Perform precise coordinated traction of the alternating electric field;

[0012] When the physiological critical window is reached, the central control unit generates alternating current, which is then output to the set target area via a ring-shaped conductive component, forming an alternating electric field with a specific slow wave frequency.

[0013] Furthermore, in the coaxial and confocal magnetoelectric composite array, the permanent magnet at the center generates an inverted conical hyperpolarization suppression magnetic field region, which converges with the radial alternating current density generated by the ring conductive component at the focal point, achieving three-dimensional spatial overlap in the set target area.

[0014] Furthermore, in step 1, the permanent magnets in the coaxial and confocal magnetoelectric composite array generate a constant static magnetic field of 0.1T-0.2T, which acts on the neural tissue of the DLPFC target area for 5 to 15 minutes.

[0015] Furthermore, in step 2, the calculation process for the cortical arousal index (ArI) is as follows:

[0016] The width and step size of the sliding time window are set, and Hamming windowing is applied to the EEG signal data sequence within each discrete sliding time window. The Welch method based on periodogram averaging is used to calculate the one-sided power spectral density distribution sequence of the EEG signal within the current sliding time window. The high-frequency band is set to 15 < f ≤ 30 Hz, the mid-frequency band to 4 < f ≤ 8 Hz, and the low-frequency band to 0.5 < f ≤ 4 Hz, where f is the frequency. The one-sided power spectral density distribution sequence within the three frequency bands is integrated to obtain the high-frequency arousal energy, transition energy, and low-frequency synchronization energy. The high-frequency arousal energy / (transition energy + low-frequency synchronization energy) is used as the cortical arousal index.

[0017] Furthermore, in step 2, the central control unit monitors the cortical arousal index in real time to determine the specific process of reaching the physiological critical window:

[0018] Step 2-1: Establishing the State Baseline and Removing Outliers

[0019] The initial set time period Tbase=180 seconds for passive magnetic static pre-suppression is used as the state baseline calibration area; cortical arousal index samples are collected on the state baseline calibration area, and outlier removal based on interquartile range is performed to retain valid cortical arousal index samples; the arithmetic mean of M valid cortical arousal index samples is taken to generate the individualized absolute reference baseline for the current operating cycle. :

[0020]

[0021] Where 1≤m≤M, The m-th effective cortical arousal index;

[0022] Step 2-2: Dynamic trigger threshold generation and real-time trajectory tracking

[0023] The central control unit uses the set attenuation coefficient. Calculate and generate dynamic trigger threshold :

[0024]

[0025] During the passive magnetic pre-suppression process, the central control unit compares the real-time cortical arousal index with the dynamic trigger threshold at a set time step.

[0026] Steps 2-3: Disturbance Resistance Time Window Criterion and State Machine Transition Triggering

[0027] Initialize continuous counter C valid =0; when ArI(t) ≤ At that time, C valid Increment by 1, if at some moment ArI(t) > When this happens, blocking is triggered, C valid Reset immediately; the optimal physiological critical window is determined only when the continuous counter reaches the preset continuous threshold N.

[0028] Furthermore, in step 3, the alternating current is a low-dose, small alternating current, ≤1.0mA.

[0029] Furthermore, in step 3, the AC power generation employs a soft-start mechanism. The arbitrary waveform generator in the central control unit generates a standard digital sine sequence at the target frequency, which is then output as a constant current source through a digital-to-analog converter and a voltage-controlled constant current source circuit. A linearly increasing time envelope function is applied to the constant current source, and the soft-start time T is set. ramp =30 seconds, the current amplitude of the constant current source smoothly and strictly linearly increases from 0mA to the set target operating threshold during the soft start time. The target operating threshold is set to 0.5mA≤I target ≤1.0mA.

[0030] The beneficial effects of this invention are:

[0031] (1) Constructing a sensorless and efficient rhythmic traction mechanism based on tSMS hyperpolarization preset and low-frequency tACS synergy.

[0032] The main objective of this invention is to pre-set the cortical electrophysiological state via tSMS to synergistically enhance the rhythmic traction efficiency of tACS and eliminate its stimulation side effects. Specifically, by utilizing the constant magnetic field generated by tSMS, and based on diamagnetic anisotropy to reduce the probability of voltage-gated ion channel opening, hyperpolarization deflection is induced in the resting membrane potential of cortical neurons. This hyperpolarization effect effectively suppresses endogenous high-frequency oscillations, significantly improves the signal-to-noise ratio of the cortical network, and greatly increases the sensitivity of the neural network to external low-frequency electric fields. Under this pre-set low-excitability physiological state, tACS can induce precise locking of neuronal firing phase and large-scale slow-wave synchronization at extremely low output current intensity (≤1.0mA). This synergistic mechanism not only overcomes the bottleneck of tACS's dependence on the brain's initial state but also completely avoids the harmful somatosensory nerve activation and retinal heteropolarization caused by high-intensity alternating current, cutting off the defensive arousal pathway triggered by unexpected sensory input, thereby achieving efficient sleep regulation under the premise of imperceptibility and high comfort.

[0033] (2) Construct a precise closed-loop intervention mechanism based on the cortical arousal index (ArI) quantification.

[0034] This invention aims to overcome the shortcomings of existing closed-loop systems that rely on delayed sleep EEG characteristics, and to construct a prospective triggering mechanism based on dynamic quantification of cortical excitability. It extracts and tracks the evolution of the power spectral density of the target frequency band from real-time EEG data to calculate the ArI value. Based on the decay trajectory of the ArI value, the system objectively determines whether the hyperpolarization inhibition effect induced by tSMS has reached the physiological critical point for optimal acceptance of exogenous rhythmic traction. tACS intervention is automatically triggered only at a precise moment when high-frequency network activity is sufficiently suppressed, achieving a strict dynamic fit between the physical field intervention sequence and the evolution of the neurodynamic state.

[0035] (3) Achieving precise spatial coverage of the target brain region by a coaxial, confocal magnetoelectric composite array

[0036] This invention aims to address the problem of target area anatomical misalignment in multimodal synergistic stimulation using magnetic and electric fields, and designs and provides an integrated coaxial magnetoelectric composite electrode structure. By integrating a strong permanent magnet and a ring-shaped conductive electrode on the same physical central axis, it ensures a high degree of three-dimensional spatial overlap between the hyperpolarization inhibition core region mediated by the static magnetic field and the focus of the rhythmic traction current density driven by the alternating electric field at the intracranial cortical tissue level, thereby guaranteeing that the sequential synergistic regulatory effect is fully realized in the same neuronal population. Attached Figure Description

[0037] Figure 1 This is a general principle block diagram of the method described in this invention;

[0038] Figure 2 A schematic diagram of a coaxial, confocal magnetoelectric composite array;

[0039] Figure 3 A schematic diagram illustrating the spatial coaxial mapping principle of the magnetic and electric fields generated by a coaxial and confocal magnetoelectric composite array within the cortex;

[0040] Figure 4 This is a flowchart of the closed-loop monitoring and trigger determination algorithm in the central control unit of the method described in this invention;

[0041] Figure 5 This is a time series diagram showing the evolution of the cortical arousal index and the stimulation intensity in the method described in this invention;

[0042] Figure 6 The graph shows the effect of tSMS and tACS synergistic intervention on the evolution of neuronal membrane potential in the method described in the embodiment. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] This embodiment provides a closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation. Its overall principle block diagram is as follows: Figure 1 As shown, tSMS is first used to induce hyperpolarization of the membrane potential of cortical neurons, thereby reducing the baseline of cortical excitability. Then, the cortical state is quantified by real-time EEG signal mapping to accurately capture the physiological critical window of high-frequency background EEG signal decay caused by hyperpolarization. Finally, low-frequency, weak-intensity tACS intervention is automatically triggered during this window period to achieve efficient phase locking to low-frequency sleep rhythms.

[0045] The method described in this embodiment is based on a coaxial and confocal magnetoelectric composite array and a central control unit. A schematic diagram of the coaxial and confocal magnetoelectric composite array is shown below. Figure 2 As shown, it includes a permanent magnet, a ring-shaped conductive component, and miniature flexible dry electrode probes. The permanent magnet is located at the center and is cylindrical with an insulating, skin-friendly coating on its outer surface. Ring-shaped conductive electrodes (AC output / return terminals) are concentrically nested around the permanent magnet. Several miniature flexible dry electrode probes are embedded on the outer edge of the ring-shaped conductive component, which are used to collect EEG signals and drive the ring-shaped conductive component, respectively. The central control unit is used to calculate the cortical arousal index of the EEG signal, set a dynamic trigger threshold, determine the physiological critical window based on the cortical arousal index and the dynamic trigger threshold, and then control the ring-shaped conductive component to generate AC.

[0046] The schematic diagram of the spatial coaxial mapping principle of the magnetic and electric fields generated by the coaxial and confocal magnetoelectric composite array within the cortex is shown below. Figure 3 As shown, the "inverted cone" hyperpolarization suppression magnetic field core region generated by the central permanent magnet and the convergence point of the radial alternating current density generated by the ring conductive component achieve a high degree of three-dimensional overlap deep in the cortex (DLPFC gray matter layer 1.5-2.0 cm from the scalp). This ensures that the neurons suppressed by the magnetic field noise reduction and the neurons induced by the electric field are completely the same population, laying the physical and anatomical foundation for subsequent magnetoelectric spatiotemporal closed-loop coordinated regulation.

[0047] Based on a coaxial, confocal magnetoelectric composite array, the method described in this embodiment embeds a forward-looking closed-loop dynamic control method within the central control unit. Unlike existing sleep intervention devices that blindly open-loop output or rely on delayed sleep EEG characteristics for triggering in a single control mode, the core innovation of the method described in this embodiment lies in constructing a rigorous electrophysiological collaborative logic chain from magnetic field foundation building, EEG seeking, to final electric field traction.

[0048] The specific process of the method described in this embodiment is as follows:

[0049] Step 1: Perform passive magnetic pre-inhibition to reshape the basic electrophysiological state of the cortex.

[0050] In the initial stage of intervention, the cortical network of insomnia patients is usually in a highly desynchronized, high-frequency arousal state. Directly applying alternating current is not only ineffective but also easily triggers arousal. Therefore, in this embodiment, the output of alternating current is completely locked in the first intervention stage (shielding electric field disturbances), and the target area is passively pre-processed solely by the constant static magnetic field generated by the permanent magnet at the center of the magnetoelectric composite array. Utilizing the antimagnetic anisotropy effect of the static magnetic field, the voltage-gated ion channels of the target area neurons are forced to produce conformational blockade. This process, without inducing any somatosensory side effects, forces the resting membrane potential of neurons to irreversibly shift from a "depolarized active state" to a "hyperpolarized inhibitory state" at the physical microscopic level, thereby effectively clearing high-frequency background noise in the cortex and laying a high signal-to-noise ratio physiological foundation for subsequent rhythmic traction.

[0051] This embodiment operates in a static magnetic pre-regulation mode without relying on transient triggering, but rather based on a dynamic accumulation mechanism of microscopic deformation of the static magnetic field. The 0.1T-0.2T effective magnetic field generated by the central permanent magnet continuously acts on the neural tissue of the DLPFC target area. As the runtime accumulates (the system's pre-processing time window is typically 5 to 15 minutes), the conformational blocking effect of voltage-gated ion channels (Na+ and Ca2+ channels) induced by diamagnetic anisotropy continuously superimposes at the microscopic level, gradually restricting the influx of excitatory cations into the target area's neural network. At the macroscopic network dynamics level, this continuous physical field input forces the resting membrane potential of the target area's neuronal population to irreversibly shift from a depolarized state to a hyperpolarized inhibitory state, systematically suppressing high-frequency background electrophysiological activity from the hardware level.

[0052] Step 2: Perform real-time quantification of cortical state and dynamic optimization of physiological critical window.

[0053] During the static magnetic pre-inhibition process, the system does not passively wait but instead acquires EEG signals from the target area in real time using miniature flexible dry electrode probes. The central control unit constructs a nonlinear cortical arousal index (ArI) by continuously extracting high-frequency arousal energy and low-frequency synchronization energy from the EEG signals. This index can objectively and dynamically quantify the degree of inhibition of high-frequency networks by the static magnetic field. In this embodiment, not only is an individualized baseline established based on the subject's initial state, but the decay trajectory of the ArI value is also continuously tracked. When the ArI value is detected to stably fall below the dynamic threshold within a preset time window, the system can prospectively determine that the target area neurons have reached a deep hyperpolarization state, the T-type calcium channels are about to be deactivated, and the cortical network has entered the physiological critical window most suitable for receiving exogenous low-frequency rhythmic traction.

[0054] The construction process of the cortical arousal index (ArI) is as follows:

[0055] To overcome the randomness of fluctuations in the amplitude of time-domain EEG signals, the central control unit executes a frequency-domain power integration algorithm with a continuously sliding time window to construct an internal control variable ArI that characterizes the degree of inhibition of the cortical resting membrane potential.

[0056] (1) Data slicing and window function smoothing: The algorithm sets the sliding time window width W=10 seconds and the sliding step size Δt=2 seconds. Hamming window processing is applied to the EEG signal data sequence within each discrete time window to suppress spectral leakage during the fast Fourier transform operation.

[0057] (2) Power spectral density estimation: Welch method based on periodogram averaging is used to calculate the one-sided power spectral density distribution sequence P(f) of the EEG signal within the current time window, where f is the frequency.

[0058] (3) Absolute power integration in specific dynamic frequency bands: The central control unit extracts the total power of three frequency bands representing different network states through numerical integration calculations:

[0059] High-frequency wake-up energy (P) β The high-frequency noise floor level of the cortical network with high desynchronization is mapped to the power in the high-frequency band (15 < f ≤ 30 Hz), and the specific formula is as follows:

[0060]

[0061] in, For the frequency differential component;

[0062] Transitional energy (P) θ The intermediate frequency band (4 < f ≤ 8 Hz) characterizes the intermediate state features of the network topology evolution from desynchronization to synchronization, and the specific formula is shown below:

[0063]

[0064] Low-frequency synchro energy (P δ The low-frequency band (0.5 < f ≤ 4 Hz) directly reflects the degree of establishment of large-scale hyperpolarization synchronization in the thalamus-cortex circuit, and the specific formula is shown below:

[0065]

[0066] (4) Real-time mapping formula for the ArI exponent:

[0067] The control variable ArI(t) of the real-time calculation system at time t is calculated according to the following formula:

[0068]

[0069] This nonlinear ratio formula quantifies the antagonistic ratio between "high-frequency wake-up drive" and "low-frequency sleep drive." During the magnetostatic pre-regulation mode, as the ion channel conformation is blocked by the magnetostatic field, molecular P... β The ArI(t) variable exhibits a decaying trend, while the hyperpolarization of the membrane potential increases the probability of spontaneous low-frequency oscillations in the T-type calcium channels, leading to an increase in the denominator. Therefore, the continuous decay characteristic of the ArI(t) variable is used by the system as the core algorithm criterion for evaluating "whether the pre-suppression state meets the standard" and "when to trigger subsequent AC traction".

[0070] Traditional neuromodulation devices often rely on fixed-delay open-loop control for intervention timing, which cannot respond to the dynamic evolution of individual cortical network states and is prone to "spatiotemporal mismatch" between physical field application and neuronal reception. To address this, this embodiment embeds a prospective closed-loop triggering algorithm based on Arl(t) decay trajectory within the central control unit. This algorithm, as the core decision logic, aims to precisely pinpoint the microscopic physical critical window where the target area membrane potential reaches its lowest desynchronization noise floor due to the cumulative effect of the static magnetic field, making it most suitable for responding to low-frequency traction.

[0071] The flowchart of the closed-loop monitoring and trigger determination algorithm in the central control unit is as follows: Figure 4 As shown, the specific process is as follows:

[0072] Step 2-1: Establishing the State Baseline and Removing Outliers

[0073] The first preset time period after entering the magnetostatic pre-regulation mode (set time window Tbase=180 seconds) is defined as the baseline calibration period. During this period, a mathematical reference frame for the initial high-arousal state of the cortex is established by collecting multiple ArI sample points on discrete time series.

[0074] To prevent baseline contamination from extreme data caused by transient electromyography artifacts, sudden changes in line impedance, or system preheating instability, the central control unit executes an outlier removal procedure based on interquartile range. After removing invalid samples, the system calculates the arithmetic mean of the remaining M valid cortical arousal index samples to generate an individualized absolute reference baseline for this operating cycle. :

[0075]

[0076] Where 1≤m≤M, denoted as the m-th effective cortical arousal index.

[0077] The baseline parameters are written into the non-volatile register of the central control unit in real time, serving as the anchor point for subsequent dynamic comparisons.

[0078] Step 2-2: Dynamic Threshold Generation and Real-time Trajectory Tracking

[0079] After baseline calibration is completed, the real-time tracking loop begins. The central control unit automatically calculates and generates a dynamic trigger threshold based on the set attenuation coefficient α (preferably within the range of 0.6 ≤ α ≤ 0.75; the specific value can be written via the external system parameter configuration interface). :

[0080]

[0081] During the ongoing static magnetic pre-control, the data comparator of the central control unit continuously compares the real-time wake-up index ArI(t) calculated at the current moment with the trigger threshold at a set time step. Perform the difference operation. When ArI(t) shows a decreasing trend and approaches... At this point, it indicates that the hyperpolarization effect of the membrane potential mediated by the static magnetic field has substantially suppressed the high-frequency discharge network of the cortex, and the pre-suppression state is deemed to have met the standard.

[0082] Steps 2-3: Disturbance Resistance Time Window Criterion and State Machine Transition Triggering

[0083] Because EEG signals are inherently highly non-stationary and non-linear, a drop in Arl(t) below the threshold within a single time window is highly likely due to random fluctuations. To avoid false positives in the state machine, a duration criterion for debounce logic is introduced after the comparator stage.

[0084] (1) Initialize a continuous counter (C) in memory. valid =0).

[0085] (2) When ArI(t)≤ is detected At that time, C valid Increment by 1 (C) valid =C valid +1); if at some moment ArI(t) > When this happens, blocking is triggered, C valid Reset immediately.

[0086] (3) When the counter reaches the preset continuous threshold N (preferably N=5, that is, 5 consecutive overlapping time windows are detected, which is equivalent to a stable state for 10 consecutive seconds), it is determined to be the optimal physiological critical window, the optimal traction window is established, and subsequent AC traction is triggered.

[0087] Step 3: Trigger state machine transition to execute precise coordinated traction based on extremely low dose alternating electric field.

[0088] The AC stimulation module will be automatically activated only after the aforementioned physiological critical window is successfully locked. The central control unit immediately interrupts the current static magnetic single-mode operation and generates a weak alternating electric field with a specific slow-wave frequency, which is output to the target area via a ring-shaped conductive component. The core innovation lies in the nonlinear resonant amplification effect generated by the magnetoelectric synergy: thanks to the prior static magnetic pretreatment that pushes the neuronal membrane potential to an absolute potential threshold extremely close to the opening of T-type calcium channels, the system only needs to output a very low dose of tiny alternating current (≤1.0mA). The resulting tiny depolarization perturbation can trigger concentrated neuronal firing at extremely low energy cost, achieving efficient firing phase locking and whole-brain slow-wave synchronization. This extremely low-intensity electric field perfectly crosses the energy threshold that triggers scalp pain and visual hallucinations, completely severing the defensive arousal pathway caused by intervention side effects.

[0089] Once the central control unit determines that the target cortical network has completed membrane potential pre-suppression and issues a trigger command, it enters the same-frequency resonance traction mode. In this mode, the system fully utilizes the high signal-to-noise ratio and hyperpolarized physiological conditions established by the previous tSMS, and outputs an extremely low dose of alternating electric field through the tACS module to perform oscillation and phase locking on the network. The specific execution logic and hardware control flow are as follows:

[0090] Step 3-1, Micro-current Soft Start Settings

[0091] To prevent sudden changes in the electric field from introducing a step response containing high-frequency harmonic components at the brain tissue-electrode interface, thereby triggering a startle reflex in the neural network, the AC stimulation generation unit of this system incorporates a high-precision waveform envelope modulator. For example... Figure 5 As shown, the evolution of the cortical arousal index and the time series diagram of stimulation intensity (effect and time series diagram).

[0092] (1) Waveform synthesis and digital-to-analog conversion: The arbitrary waveform generator inside the central control unit generates a target frequency of f. target A standard digital sine wave sequence (set in the 0.5Hz-2Hz slow wave band range) is output through a high-resolution digital-to-analog converter (DAC) and a voltage-controlled constant current source circuit.

[0093] (2) Slow-start linear envelope: the output amplitude I of the constant current source out (t) is governed by a linearly increasing time envelope function. The system is set to a soft-start time T. ramp =30 seconds, during which the current amplitude smoothly and strictly linearly increases from 0mA to the target operating threshold I. target .

[0094] (3) Extremely low dose parameter setting: Thanks to the optimization of the system state induced by static magnetostatics in the early stage, the target working threshold I of this invention is target It was greatly reduced to 0.5mA≤Itarget ≤1.0mA (preferably set to 0.8mA). This current intensity is far below the activation threshold of pain nerve fibers in traditional electrical stimulation devices, completely avoiding somatic side effects from the physical output source.

[0095] Step 3-2, Subthreshold Fine-tuning Traction Intervention

[0096] When the output current stabilizes at an extremely low dose of 0.8 mA, the ring electrode of the composite array forms a weak converging alternating electric field (local electric field gradient <0.1 V / m) below the DLPFC target region. This electric field induces a highly efficient synergistic traction effect at the cortical microdynamic level:

[0097] (1) Physiological threshold approximation: Because the static magnetic field has hyperpolarized the resting membrane potential of the pyramidal neurons, its baseline is extremely close to that of T-type voltage-gated calcium channels (T-type Ca2+). 2+ The absolute potential threshold for deactivating channels.

[0098] (2) Nonlinear resonant amplification: At this time, a weak 1Hz external alternating electric field is applied as a periodic forcing force to the cortical network that is already on the critical edge. In the pure background where there is no interference from high-frequency brain electrical activity (Beta wave), every small perturbation of the external electric field in the depolarization phase can trigger the opening of T-type calcium channels at a very low energy cost, thereby inducing low-threshold calcium spikes.

[0099] (3) Macroscopic phase locking: Under the phase constraint of the external alternating electric field, the firing probability of the massive number of neurons in the target area is forcibly redistributed, and a high degree of spatial and temporal synchronization (i.e., phase locking) is rapidly achieved. This local synchronization oscillation is further amplified in an avalanche cascade in the topological network of the cortico-thalamic circuit, forcibly guiding the whole brain network into a low-frequency synchronization mode.

[0100] The curve showing the effect of tSMS and tACS synergistic intervention on neuronal membrane potential evolution in the method described in this embodiment is as follows: Figure 6 As shown, the method described in this embodiment perfectly resolves the deadlock between rhythmic traction efficiency and stimulus side effects in traditional modulation techniques by first reducing excitation and then inducing rhythm in a spatiotemporal dual-dimensional synergy. To ensure the accurate implementation of the above macroscopic synergistic logic, the system is designed with highly targeted signal processing algorithms and microscopic parameter control mechanisms at the underlying computational level.

Claims

1. A closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation, characterized in that, This is achieved using a coaxial, confocal magnetoelectric composite array and a central control unit. The coaxial, confocal magnetoelectric composite array includes a permanent magnet, a ring-shaped conductive component, and miniature flexible dry electrode probes. The permanent magnet is located at the center, is cylindrical, and has an insulating, skin-friendly coating on its outer surface. Ring-shaped conductive electrodes are concentrically nested around the permanent magnet. Several miniature flexible dry electrode probes are embedded along the outer edge of the ring-shaped conductive component, used for real-time acquisition of EEG signals and driving the ring-shaped conductive component. The central control unit is used to calculate the cortical arousal index of the EEG signal in real time, set a dynamic trigger threshold, determine the physiological critical window based on the cortical arousal index and the dynamic trigger threshold, and then control the ring-shaped conductive component to generate alternating current. The process is as follows: Step 1: Perform passive magnetic pre-inhibition to reshape the basic electrophysiological state of the cortex; The permanent magnets in the coaxial and confocal magnetoelectric composite array generate a constant static magnetic field that acts on the designated target area; Step 2: Real-time quantification of cortical state and dynamic optimization of physiological critical window; The central control unit performs frequency domain power integration over a continuous sliding time window to calculate the cortical arousal index ArI in real time. It sets a dynamic trigger threshold using the cortical arousal index ArI within the initial set time period of passive magnetic pre-inhibition. The real-time cortical arousal index ArI is compared with the dynamic trigger threshold. If the real-time cortical arousal index ArI is less than the dynamic trigger threshold within several consecutive sliding time windows, it is determined that the physiological critical window has been reached. Step 3: Perform precise coordinated traction of the alternating electric field; When the physiological critical window is reached, the central control unit generates alternating current, which is then output to the set target area via a ring-shaped conductive component, forming an alternating electric field with a specific slow wave frequency.

2. The closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation according to claim 1, characterized in that, In a coaxial and confocal magnetoelectric composite array, the permanent magnet at the center generates an inverted conical hyperpolarization suppression magnetic field region, which converges with the radial alternating current density generated by the ring conductive component at the focal point, achieving three-dimensional spatial overlap in the designated target area.

3. The closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation according to claim 1, characterized in that, In step 1, the permanent magnets in the coaxial and confocal magnetoelectric composite array generate a constant static magnetic field of 0.1T-0.2T, which acts on the neural tissue of the DLPFC target area for 5 to 15 minutes.

4. The closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation according to claim 1, characterized in that, In step 2, the calculation process of the cortical arousal index (ArI) is as follows: The width and step size of the sliding time window are set, and Hamming windowing is applied to the EEG signal data sequence within each discrete sliding time window. The Welch method based on periodogram averaging is used to calculate the one-sided power spectral density distribution sequence of the EEG signal within the current sliding time window. The high-frequency band is set to 15 < f ≤ 30 Hz, the mid-frequency band to 4 < f ≤ 8 Hz, and the low-frequency band to 0.5 < f ≤ 4 Hz, where f is the frequency. The one-sided power spectral density distribution sequence within the three frequency bands is integrated to obtain the high-frequency arousal energy, transition energy, and low-frequency synchronization energy. The high-frequency arousal energy / (transition energy + low-frequency synchronization energy) is used as the cortical arousal index.

5. The closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation according to claim 1, characterized in that, In step 2, the central control unit monitors the cortical arousal index in real time, and the specific process of determining when the physiological critical window is reached is as follows: Step 2-1: Establishing the State Baseline and Removing Outliers The initial set time period Tbase=180 seconds for passive magnetic static pre-suppression is used as the state baseline calibration area; cortical arousal index samples are collected on the state baseline calibration area, and outlier removal based on interquartile range is performed to retain valid cortical arousal index samples; the arithmetic mean of M valid cortical arousal index samples is taken to generate the individualized absolute reference baseline for the current operating cycle. : Where 1≤m≤M, The m-th effective cortical arousal index; Step 2-2: Dynamic trigger threshold generation and real-time trajectory tracking The central control unit uses the set attenuation coefficient. Calculate and generate dynamic trigger threshold : During the passive magnetic pre-suppression process, the central control unit compares the real-time cortical arousal index with the dynamic trigger threshold at a set time step. Steps 2-3: Disturbance Resistance Time Window Criterion and State Machine Transition Triggering Initialize continuous counter C valid =0; when ArI(t) ≤ At that time, C valid Increment by 1, if at some moment ArI(t) > When this happens, blocking is triggered, C valid Reset immediately; the optimal physiological critical window is determined only when the continuous counter reaches the preset continuous threshold N.

6. The closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation according to claim 1, characterized in that, In step 3, the alternating current is a low-dose, small alternating current, ≤1.0mA.

7. The closed-loop sleep aid method based on the synergistic intervention of transcranial static magnetic field and alternating current stimulation according to claim 1, characterized in that, In step 3, the AC power generation employs a soft-start mechanism. The arbitrary waveform generator in the central control unit generates a standard digital sine sequence at the target frequency, which is then output as a constant current source through a digital-to-analog converter and a voltage-controlled constant current source circuit. A linearly increasing time envelope function is applied to the constant current source, and the soft-start time T is set. ramp =30 seconds, the current amplitude of the constant current source smoothly and strictly linearly increases from 0mA to the set target operating threshold during the soft start time. The target operating threshold is set to 0.5mA≤I target ≤1.0mA.

Images