Helmet type multi-target magnetic stimulation system based on time interference theory

Abstract

The invention discloses a helmet type multi-target transcranial magnetic stimulation system based on a time interference theory. The helmet type multi-target transcranial magnetic stimulation system comprises a power supply module, an interaction module, a control circuit module, a stimulation main circuit module and a magnetic stimulation coil module, the interaction module is connected with the control circuit module, the control circuit module is connected with the stimulation main circuit module, the stimulation main circuit module is connected with the magnetic stimulation coil module, and the power supply module is connected with the interaction module, the control circuit module, the stimulation main circuit module and the magnetic stimulation coil module. The magnetic stimulation coil module is a coil array composed of 15 magnetic stimulation coils, the coil array is arranged in a partitioned mode according to the frontal-temporal-apical brain area, four coils are densely arranged in the outer side area of the back of the prefrontal lobe, three coils are distributed on the upper portion of the temporal lobe, and for an auditory sense and memory integration function area, eight coils are intensively arranged on the rear portion of the central groove of the apical lobe. And preset focusing and induced electric field intensity are realized in a target region, and accurate transcranial magnetic stimulation of an individual is finally realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biomedical magnetic stimulation, and particularly relates to a helmet type multi-target magnetic stimulation system based on a time interference theory. BACKGROUND

[0002] Transcranial Magnetic Stimulation (TMS) is a non-invasive neural modulation technology based on Faraday's law of electromagnetic induction. The magnetic field induced by the stimulation coil can pass through the scalp and skull without attenuation, directly reaching the cerebral cortex, and inducing an induced current in the cortex. TMS has high temporal and spatial resolution, can stimulate specific brain regions, and does not require craniotomy, so it is safe and has been widely used in the treatment of depression, Parkinson's disease, Alzheimer's disease, schizophrenia and other diseases. Different stimulation frequencies can produce excitatory or inhibitory effects, regulate neural activity in specific brain regions, improve local cerebral blood flow, regulate neurotransmitter release, indirectly regulate brain networks, promote neural plasticity, and regulate cognitive, motor, speech, emotional and other high-level brain functions.

[0003] Temporal Interference (TI) stimulation is a non-invasive deep brain stimulation technology that delivers two sinusoidal high-frequency induced magnetic fields to the brain, uses frequency difference interference modulation to generate a magnetic field envelope, targets deep brain regions such as the hippocampus and striatum without activating cortical neurons, and achieves effective neural regulation.

[0004] Existing transcranial magnetic stimulation systems mostly use high-frequency magnetic fields, which have the significant defects of high power requirements and difficulty in portability. These defects not only affect the accuracy of treatment, but also limit the application occasions. The existing technology lacks precise height and position adjustment mechanisms and relies on the experience and operation of device operators. When the patient is ready to receive treatment, it is often difficult to ensure the precise alignment of the patient's head and the treatment components, which may cause deviations during treatment and affect the treatment effect. Secondly, the existing technology has obvious deficiencies in treatment means integration, often only providing single or limited stimulation schemes, which cannot fully meet the individual differences of patients. This singularity not only limits the improvement of treatment effect, but also may prolong the treatment cycle of patients. SUMMARY

[0005] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a head-mounted multi-target magnetic stimulation system based on time interference, which can overcome the problems of insufficient focusing and stimulation depth of TMS in the prior art, provide a coil array composed of 15 magnetic stimulation coils, adopt time interference magnetic stimulation technology, combine individual magnetic resonance data to establish a magnetic stimulation simulation head model, optimize the distribution of induced electric field, improve the focusing of stimulation, achieve the preset focusing and induced electric field intensity in the target area, and finally realize individual precise transcranial magnetic stimulation.

[0006] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is:

[0007] A helmet-type multi-target transcranial magnetic stimulation system based on time interference theory, characterized in that it comprises a power module, an interaction module, a control circuit module, a stimulation main circuit module and a magnetic stimulation coil module; the interaction module is connected with the control circuit module, the control circuit module is connected with the stimulation main circuit module, the stimulation main circuit module is connected with the magnetic stimulation coil module, and the power module is connected with the interaction module, the control circuit module, the stimulation main circuit module and the magnetic stimulation coil module.

[0008] The control circuit module comprises an STM32 core circuit and a capacitor filter circuit; the STM32 core circuit is composed of an STM32 chip, capacitors C5, C6, C7, C8, C9, C10, resistors R1, R2, R4 and R6; the STM32 chip is connected with an external sensor, an actuator and a communication module to complete signal acquisition, control output and data interaction; one end of the capacitors C6, C7, C8 and C9 is grounded, and the other end is connected with the VCC_3V3 of the STM32 chip and cooperates with the chip power pin; the capacitors C5 and C10 and the resistor R4 constitute a reset-related circuit, one end of C5 and C10 is grounded, and the other end is connected through R4 and cooperates with the chip reset pin; R1 is a pull-up resistor, one end of which is connected with VCC_3V3, and the other end is connected with the MCU_SWCLK pin of the P1 interface U2; R2 is a pull-down resistor, one end of which is grounded, and the other end is connected with the MCU_Reset pin of the P1 interface U2; one end of R6 is grounded, and the other end is connected with VCC_3V3.

[0009] Furthermore, the stimulation main circuit module includes a power control circuit and a coil drive circuit; the power control circuit includes switching transistors Q1 and Q6, a Zener diode D1, a pull-up resistor R1, a gate resistor R6, a current-limiting resistor R12, and a pull-down resistor R17; the coil drive circuit includes a pin header H1, a core driver chip U3, a sampling resistor R11, filter capacitors C8 and C9, a decoupling capacitor C1, and a pin header H2; the CL_1_PWM1 and CL_1_PWM2 pins of the pin header H1 receive external PWM control signals, the core driver chip U3 controls the switching logic of the H-bridge through the PWM signal, the sampling resistor R11 is connected in series between the ISEN pin and ground, the filter capacitors C8 and C9 are connected in parallel between the VM power supply and ground, C8 is an electrolytic capacitor, and C9 is a ceramic capacitor; the decoupling capacitor C1 is connected across the CL_1_OUT1 and CL_1_OUT2 pins of the output pin header H2.

[0010] Furthermore, the magnetic stimulation coil module is a coil array consisting of 15 magnetic stimulation coils, which are arranged in sections according to the frontotemporal-parietal regions: 4 coils are densely arranged in the dorsolateral region of the prefrontal lobe, 3 coils are distributed in the upper part of the temporal lobe, and 8 coils are concentrated in the posterior part of the central sulcus of the parietal lobe, targeting the auditory and memory integration function area.

[0011] The main innovations of this invention compared to existing technologies are as follows:

[0012] To address the issues of fluctuating efficacy, insufficient target precision, and inadequate intelligence in existing helmet-mounted multi-target magnetic stimulation (MMR) techniques, personalized functional magnetic resonance imaging (fMRI) data analysis can be used to identify fMRI characteristic indicators that are sensitive to individual recovery. This will elucidate the mechanism by which multi-target stimulation improves lesions and provide precise spatial coordinates of the lesions, thus greatly resolving the problems of fluctuating efficacy, insufficient target precision, and inadequate intelligence.

[0013] Existing multi-target synergistic TMS methods mostly rely on a single drive circuit to control all stimulation coils, meaning all coils simultaneously generate magnetic fields of the same strength. However, due to individual differences, the number and location of lesions vary, necessitating adjustments to the number and location of stimulation targets based on the individual. By developing an intelligent algorithm that can precisely and rapidly adjust the multi-coil stimulation mode based on the spatial coordinates of lesions derived from personalized fMRI data, and by regulating the drive circuits controlled by multiple independent channels to control the number and location of stimulation targets, precise treatment plans can be provided for each individual, greatly expanding the application scenarios of TMS.

[0014] Mimics software was used to segment different tissues (scalp, skull, cerebrospinal fluid, gray matter, and white matter). These tissue models were then imported into Geomagic software for optimization, including feature removal, manual delineation, smoothing, and denoising. AK software was applied for radiomics feature extraction and dimensionality reduction to determine the location and area of ​​lesions. The optimized tissue models were then imported into Comsol software to create a realistic head model. Machine learning algorithms applicable to feature selection and classification were investigated to identify characteristic indicators for precise target identification in AD patients, enabling more accurate individualized lesion target localization.

[0015] A multi-coil simulation model was constructed using Comsol software. The relationship between the number, size, and distribution of magnetic stimulation coils, as well as stimulation parameters and the distribution of the induced electric field, was analyzed. The feasibility of multi-target stimulation and the movement of the focusing area under electromagnetic stimulation were investigated. The spatial arrangement of the multi-coil and multi-electrode system was optimized to achieve precise positioning and focusing of multi-target stimulation. The movement of the focusing area under multi-target magnetic stimulation was studied, realizing multi-target synergistic magnetic stimulation. An optimized design scheme for the magnetic stimulation coil array and stimulation parameters was proposed. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention;

[0017] Figure 2 This is a schematic diagram of the circuit structure of the power module of the present invention;

[0018] Figure 3 This is a schematic diagram of the circuit structure of the driving module of the present invention;

[0019] Figure 4 This is a side view of the coil array of the present invention;

[0020] Figure 5 This is a top view of the coil array of the present invention;

[0021] Figure 6 This is a parameter diagram of the magnetic stimulation coil of the present invention. Detailed Implementation

[0022] Specific embodiments are given below with reference to the accompanying drawings. These specific embodiments are only used to describe the technical solution of the present invention in detail, and are not intended to limit the scope of protection of this application.

[0023] This invention provides a helmet-mounted multi-target transcranial magnetic stimulation system based on time-interference theory, comprising a power supply module, an interaction module, a control circuit module, a stimulation main circuit module, and a magnetic stimulation coil module; wherein, the power supply module is connected to the drive circuit, control circuit, and main circuit module; the power supply module provides operating power to the interaction module and the drive circuit module; the output terminal of the microcontroller control module is connected to the input terminal of the drive circuit module; the input terminal of the dual-capacitor power supply system is connected to the drive circuit module, and its output terminal is connected to the current testing module.

[0024] The power module supplies power to the entire transcranial magnetic stimulation system. It employs an adjustable step-down output circuit, comprised of an LM2576 series step-down switching integrated voltage regulator chip U4 and peripheral circuitry. The LM2576 voltage regulator chip is reliable, operates at a high frequency, and has a strong output current (up to 3A) drive capability, providing a stable and reliable operating voltage for the magnetic stimulation system. Internally, the chip integrates a fixed-frequency 52kHz oscillator and a V... REFThis 1.23V reference regulator contains comprehensive protection circuitry, including current limiting and thermal shutdown protection. The required external circuitry is simple, requiring only a few components to achieve voltage regulation. Specifically, the external circuitry consists of input filter capacitors C11 and C12, freewheeling diode D6, energy storage inductor L1, output filter capacitors C13 and C14, voltage divider resistors R22 and R23, and bypass capacitor C10. Input filter capacitors C11 and C12 are connected to the VIN pin of U4 and the GND pin, respectively. C11 is an electrolytic capacitor used to filter low-frequency ripple, and C12 is a ceramic capacitor used to filter high-frequency noise. Together, they stabilize the voltage input to the LM2576 chip, reducing the impact of power line interference on chip operation. The freewheeling diode D6 is connected to the OUTPUT pin of U4 and the GND pin, providing a release path for the energy stored in the energy storage inductor L1, preventing back electromotive force from damaging the chip. The circuitry includes a capacitor C10 and a voltage divider resistor R22. The capacitor C10 is connected to the OUTPUT pin and the voltage divider resistor R22. It stores energy during the on-state of the internal switching transistor (SMT) and releases it during the off-state, maintaining the continuity and smoothness of the output current and ensuring stable output voltage. Output filter capacitors C13 and C14 are connected to the L1 pin and the GND pin, respectively. C13 is an electrolytic capacitor used to filter low-frequency ripple, and C14 is a ceramic capacitor used to filter high-frequency noise, further filtering the output voltage to make the DC output voltage more stable and meet the load's power quality requirements. A bypass capacitor C10 is connected in parallel with the voltage divider resistor R22 to further filter high-frequency noise in the output voltage, providing a more stable power supply to the load. A voltage divider network composed of resistors R22 and R23 is connected to the FB pin of the U4. By changing the ratio of these two resistors, the voltage fed back to the chip can be adjusted, thereby setting the output voltage V. OUT With feedback voltage V REF The relationship (LM2576 chip internal reference voltage, typically 1.23V) is as follows:

[0025]

[0026] The interactive module provides human-computer interaction functions to users through a host computer interface. The human-computer interaction functions include importing the user's individual fMRI image data to select stimulation targets for relevant diseases, and visually displaying the location of the stimulation targets and detailed stimulation parameters.

[0027] The control circuit module is connected to the power supply module, drive circuit module, and magnetic stimulation coil module. It consists of an STM32 core circuit and a capacitor filter circuit, providing PWM waveform control for the drive circuit module to achieve information processing and central control functions. The STM32 core circuit is composed of an STM32 chip U2, capacitors C5, C6, C7, C8, C9, C10, and resistors R1, R2, R4, and R6. The core microcontroller STM32 chip of the control system is used to process logic and control tasks, connecting to external sensors, actuators, and communication modules to complete signal acquisition, control output, and data interaction. One end of capacitors C6, C7, C8, and C9 is grounded, and the other end is connected to VCC_3V3 of U2, matching the chip's power supply pins (such as VDD, VSS, etc.). The circuit consists of a combination of capacitors C5 and C10 and resistor R4, which together achieve power supply filtering and decoupling, stabilize the power supply voltage, and reduce noise. C5 and C10, along with resistor R4, form a reset-related circuit. One end of C5 and C10 is grounded, and the other end is connected via R4, cooperating with the chip's reset pin (NRST). When the relevant pin is pulled low, it triggers a microcontroller reset. R1 is a pull-up resistor, with one end connected to VCC_3V3 and the other end connected to the MCU_SWCLK pin of interface U2 on P1, pulling the debug clock signal high by default to ensure stable debug communication. R2 is a pull-down resistor, with one end grounded and the other end connected to the MCU_Reset pin of interface U2 on P1, normally pulling the reset signal low and playing an auxiliary role when triggering a reset. R6 is grounded at one end and connected to VCC_3V3 at the other, used for specific pin level configuration to avoid floating interference.

[0028] The drive circuit module consists of two parts: a power control circuit and a coil drive circuit. The power control circuit specifically comprises switching transistors Q1 and Q6, a Zener diode D1, a pull-up resistor R1, a gate resistor R6, a current-limiting resistor R12, and a pull-down resistor R17, providing controllable power to the VM pin of the DRV8870 chip in the coil drive circuit. When the "CL_1_45V_control" input is high, switching transistor Q6 is turned on, pulling down the source voltage of Q1 (the turn-on condition for a P-channel MOS is: gate voltage < source voltage), thus turning on Q1. When the input is low, Q6 is turned off, and Q1 is turned off due to the disappearance of the gate-source voltage difference. When the main power switching transistor Q1 is on, VCC is output to VCC_CL_1 via Q1, supplying power to the VM pin of the DRV8870. The circuit consists of: a power supply; a voltage regulator diode D1; a pull-up resistor R1; a pull-up resistor R1; a gate resistor R6; a gate resistor R6; a gate resistor R1; a current-limiting resistor R12; a current-limiting resistor R12; a current-limiting resistor R17; a pull-down resistor R17; and an output diode D25. The output diode D25 is used to prevent the voltage at the VCC_CL_1 terminal from flowing back into Q1, protecting the preceding circuitry and accelerating discharge during power switching.

[0029] The coil drive circuit module specifically consists of pin header H1, core drive chip U3, sampling resistor R11, filter capacitors C8 and C9, decoupling capacitor C1, and pin header H2. External PWM control signals are received by the CL_1_PWM1 and CL_1_PWM2 pins of pin header H1. By adjusting the PWM duty cycle, the coil voltage is changed to achieve coil excitation. Simultaneously, in conjunction with IN1 / IN2, the direction of the excitation current is changed. The core drive chip U3 controls the switching logic of the H-bridge through the PWM signal. Internally, it includes power switching transistors, logic control circuits, overcurrent protection modules, etc., and externally, it works with power supplies, capacitors, resistors, and other components to achieve the excitation of the magnetic stimulation coil. A current sampling resistor R11 is connected in series between the ISEN pin and ground. When current flows through R11, a voltage difference is generated and fed back to the DRV8870 for overcurrent protection and current monitoring. Filter capacitors C8 and C9 are connected in parallel between the VM power supply and ground. C8 is an electrolytic capacitor used to filter out low-frequency ripple, stabilize the power supply, and avoid voltage fluctuations. C9 is a ceramic capacitor used to filter out high-frequency noise, suppress spike interference on the power line, and ensure the stability of the chip's logic circuits and power switches. Decoupling capacitor C1 is connected across the output header H2 between CL_1_OUT1 and CL_1_OUT2 to suppress voltage spikes, reduce electromagnetic interference (EMI) during motor operation, and minimize the impact on other circuits.

[0030] The magnetic stimulation coil module consists of an array of 15 magnetic stimulation coils. This coil array is suitable for transcranial magnetic stimulation (TMS) of deep brain targets in various neurological diseases. The stimulation parameters can be adjusted through a control module to dynamically change the area, intensity, and stimulation mode of the stimulation focal region. The array supports high spatial resolution TMS and can achieve real-time dynamic control of stimulation position and intensity.

[0031] The magnetic stimulation coil uses an I-shaped magnetic core, wound with 1810 turns of 0.08mm diameter enameled wire. Its nominal inductance is 200mH ± 10%, its DC resistance is 400Ω, and its maximum dimensions are 31.0mm (height) × 27.5mm (width) × 8.5mm (thickness). This design helps to improve the stimulation depth and focusing performance of the time-interference magnetic field.

[0032] The coil array is arranged in zones according to the frontotemporal-parietal brain regions: four coils are densely arranged in the dorsolateral region of the prefrontal lobe to cover brain regions related to higher cognitive functions; three coils are distributed in the upper temporal lobe, targeting the auditory and memory integration function area; and eight coils are concentrated in the posterior part of the central sulcus of the parietal lobe to target the primary sensorimotor cortex and the inferior parietal lobule association area. The entire coil array is spatially arranged spherically, with its curvature matching the anatomical surface of the human skull, forming a full-coverage helmet-like structure, with each coil fitting well to the head surface. The coil spacing is not uniform, but all maintain an attenuation distance of more than 2 cm to effectively avoid mutual magnetic field interference.

[0033] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A helmet-mounted multi-target transcranial magnetic stimulation system based on time-interference theory, characterized in that, It includes a power supply module, an interaction module, a control circuit module, a stimulation main circuit module, and a magnetic stimulation coil module; the interaction module is connected to the control circuit module, the control circuit module is connected to the stimulation main circuit module, the stimulation main circuit module is connected to the magnetic stimulation coil module, and the power supply module is connected to the interaction module, the control circuit module, the stimulation main circuit module, and the magnetic stimulation coil module. The control circuit module includes an STM32 core circuit and a capacitor filtering circuit. The STM32 core circuit consists of an STM32 chip U2, capacitors C5, C6, C7, C8, C9, C10, and resistors R1, R2, R4, and R6. The STM32 chip connects to external sensors, actuators, and communication modules to complete signal acquisition, control output, and data interaction. One end of capacitors C6, C7, C8, and C9 is grounded, and the other end is connected to the STM32 chip's VCC_3V3 pin, cooperating with the chip's power supply pin. Capacitors C5 and C10, along with resistor R4, form a reset-related circuit. One end of C5 and C10 is grounded, and the other end is connected via R4, cooperating with the chip's reset pin. R1 is a pull-up resistor, with one end connected to VCC_3V3 and the other end connected to the MCU_SWCLK pin of interface U2 (P1 interface). R2 is a pull-down resistor, with one end grounded and the other end connected to the MCU_Reset pin of interface U2 (P1 interface). R6 is grounded and connected to VCC_3V3.

2. The helmet-mounted multi-target transcranial magnetic stimulation system based on time interference theory according to claim 1, characterized in that, The stimulation main circuit module includes a power control circuit and a coil drive circuit. The power control circuit includes switching transistors Q1 and Q6, a Zener diode D1, a pull-up resistor R1, a gate resistor R6, a current-limiting resistor R12, and a pull-down resistor R17. The coil drive circuit includes a pin header H1, a core driver chip U3, a sampling resistor R11, filter capacitors C8 and C9, a decoupling capacitor C1, and a pin header H2. The CL_1_PWM1 and CL_1_PWM2 pins of the pin header H1 receive external PWM control signals. The core driver chip U3 controls the switching logic of the H-bridge through the PWM signal. The sampling resistor R11 is connected in series between the ISEN pin and ground. The filter capacitors C8 and C9 are connected in parallel between the VM power supply and ground. C8 is an electrolytic capacitor, and C9 is a ceramic capacitor. The decoupling capacitor C1 is connected across the CL_1_OUT1 and CL_1_OUT2 pins of the output pin header H2.

3. The helmet-mounted multi-target transcranial magnetic stimulation system based on time interference theory according to claim 1, characterized in that, The magnetic stimulation coil module is a coil array consisting of 15 magnetic stimulation coils, which are arranged in sections according to the frontotemporal-parietal regions: 4 coils are densely arranged in the dorsolateral region of the prefrontal lobe, 3 coils are distributed in the upper part of the temporal lobe for the auditory and memory integration function area, and 8 coils are concentrated in the posterior part of the central sulcus of the parietal lobe.

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