Transcranial magnetic stimulation system based on time interference

Abstract

A transcranial magnetic stimulation system based on time interference is characterized by comprising a constant voltage source module, a single-chip microcomputer control module, a drive circuit module, a power supply module, a double-capacitor power supply system and a current measurement module. The stimulation effect of the TI-TMS system is better than that of a traditional rTMS; in order to enhance the heat dissipation capability of the PCB and enable the PCB to pass through a larger current, a double-layer PCB structure is designed, compared with a traditional over-large-current copper bar welding mode, the impedance of the double-layer PCB structure is greatly reduced, if the performance of the PCB needs to be further improved, the PCBs can be continuously connected in parallel on the basis of the double-layer PCB, and the more the PCBs connected in parallel are, the better the performance is; on the premise of reaching the same stimulation intensity, the energy required by the coil used in the invention is lower than that required by the traditional TMS; the amplitude and the frequency are adjustable, and the amplitude and the frequency can be changed by modifying a constant voltage source and a control signal.

Description

[Technical field]

[0001] The present invention relates to the field of transcranial magnetic stimulation in neural regulation technology, and in particular to a transcranial magnetic stimulation system based on time interference. [Background technology]

[0002] Transcranial Magnetic Stimulation (TMS) is a non-invasive neuromodulation method that has been widely used in the treatment of depression, Parkinson's disease, Alzheimer's disease, schizophrenia and other diseases. During the implementation of TMS, the stimulation coil is placed close to the target area of ​​the head, and the energy storage capacitor is used to discharge the stimulation coil, generating a time-varying pulse current in the stimulation coil and forming a primary induced magnetic field in the space around the coil. Since the electrical conductivity and magnetic permeability of intracranial biological tissue are not zero, the primary induced magnetic field induces a secondary induced electric field in the intracranial target area. The induced electric field acts on neurons, changes the neuronal membrane potential, and plays a role in neuromodulation.

[0003] In recent years, animal TMS experimental research has received more and more attention, and animal models play an important role in understanding the mechanism of TMS. Animal TMS experiments have many advantages. First, due to safety and ethical considerations, many experimental studies related to the mechanism of TMS cannot be conducted directly on humans, and are generally conducted through animal experiments; secondly, animals are small in size, grow fast, and have high reproduction rates. It is relatively easy to prepare animal models such as dementia, simulate the pathogenesis of human diseases and the response to drugs, thereby greatly saving time, reducing research costs, and accelerating the treatment and development of TMS in brain diseases.

[0004] Although there are more and more animal TMS experimental studies in recent years, there are still many limitations when conducting animal experiments due to the small size of animals. For example, when using a traditional magnetic stimulation system, the system's focusing ability is not strong, and it cannot meet the needs of magnetic stimulation of specific areas in the brain. For animals, it is whole-brain stimulation, and it is impossible to achieve individual stimulation of deep brain structures or a specific area. Temporal interference magnetic stimulation can solve this problem. It has a large stimulation intensity and stimulation depth, while maintaining good focusing.

[0005] Although temporal interference magnetic stimulation technology has achieved some encouraging results in laboratory research, it is still in its preliminary stage in clinical application and more research is needed to verify its efficacy and safety. Due to the insufficient focusing ability of the traditional TMS system and the trade-off between the stimulation depth and the focusing line, the stimulation of animals is whole-brain stimulation, and it is impossible to stimulate specific areas or deep brain areas. Therefore, the present invention intends to explore the technical problem of the effect of TMS on a certain area in an animal model. [Summary of the invention]

[0006] The purpose of the present invention is to provide a transcranial magnetic stimulation system based on time interference, which can overcome the problems of insufficient focusing and stimulation depth of TMS in the prior art. It is a transcranial magnetic stimulation system with a simple structure and easy implementation. The system adopts time interference magnetic stimulation technology (TI-TMS, Temporal Interference Magnetic Stimulation) and utilizes a dual-capacitor power supply circuit to enable the system to implement TI-TMS, thereby improving the stimulation effect of the system, and the system structure is simple and easy to implement.

[0007] The technical solution of the present invention is: a transcranial magnetic stimulation system based on time interference, characterized in that it includes a constant voltage source module, a single-chip control module, a driving circuit module, a power supply module, a dual-capacitor power supply system and a current measurement module; wherein the constant voltage source module is connected to the driving circuit module; the power supply module provides working power for the single-chip control module and the driving circuit module; the output end of the single-chip control module is connected to the input end of the driving circuit module; the input end of the dual-capacitor power supply system is connected to the driving circuit module, and its output end is connected to the current testing module.

[0008] The constant voltage source module is composed of a constant voltage source MS1520DS, which is used to provide the required voltage for the TI-TMS system. Since it can achieve continuously adjustable voltage of 0-30V and current of 0-60A with a resolution of 10mV and 10mA respectively, the stimulation intensity of TI-TMS can be changed by only changing the voltage of the constant voltage source.

[0009] The driving circuit module is used to correctly switch the circuit mode according to the requirements of the control signal, so that the capacitor is continuously charged and discharged to generate a continuous sinusoidal current, and is composed of a logic output optocoupler G1, a MOS tube Q11 and a peripheral circuit; the logic output optocoupler G1 is used to isolate the large current signal at both ends of the MOS tube Q11 to prevent the large current signal from interfering with the control signal and causing inaccurate action, and at the same time amplify the control signal sent by the single-chip control module to make the MOS tube Q11 act more quickly; the MOS tube Q11 is used to correctly switch the circuit mode according to the control signal of the single-chip control module to correctly generate a continuous sinusoidal current.

[0010] The driving circuit module is specifically composed of a pin header H1, a pin header H2, a pin header H3, a current limiting resistor R1, a logic output optocoupler G1, a current limiting resistor R2, a diode D1, an anti-breakdown resistor R3, a MOS tube Q11, a wiring terminal U1, and a wiring terminal U2; the 1 terminal of the pin header H1 is connected to the AN terminal of the logic output optocoupler G1 through the current limiting resistor R1, wherein the purpose of the current limiting resistor R1 is to limit the current flowing into the logic output optocoupler G1 to prevent the logic output optocoupler G1 from being damaged by excessive current; the 2 terminal of the pin header H1 is connected to the CAT terminal of the logic output optocoupler G1, and its purpose is to form a loop with the pin header H1, the current limiting resistor R1, and the logic output optocoupler G1 so that the control signal passes through the pin header H1 flows into the logic output optocoupler G1; the pin H2 is connected to the VCC end of the logic output optocoupler G1, in order to pass the power supply to the logic output optocoupler G1 through H2; the GND end of the logic output optocoupler G1 is grounded through the pin H3; the VO end of the logic output optocoupler G1 is connected in series to the gate G pole of the MOS tube Q11 through the current limiting resistor R2; the diode D1 is reversely connected in parallel to the current limiting resistor R2, so that the control signal amplified by the logic output optocoupler G1 is transmitted to the G pole of the MOS tube Q11; the current limiting resistor R2 is used to limit the current flowing into the MOS tube Q11 to prevent the MOS tube Q11 from being damaged by excessive current; the diode D1 is used to make the source-gate capacitor C on the MOS tube Q11 gs Rapid charging and discharging makes the MOS tube Q11 turn off more quickly; the two ends of the anti-breakdown resistor R3 are connected to the gate G pole and the source S pole of the MOS tube Q11, and its purpose is to prevent the MOS tube from being broken down when it is turned on without driving; one end of the wiring terminal U1 and the wiring terminal U2 are respectively connected to the drain D pole and the source S pole of the MOS tube Q11, and the other ends of the wiring terminal U1 and the wiring terminal U2 are respectively connected to the dual-capacitor power supply system, so that the MOS tube Q11 can correctly switch the circuit mode of the dual-capacitor power supply system.

[0011] The core components of the driving circuit module are the logic output optocoupler G1 and the MOS tube Q11; wherein the logic output optocoupler adopts the TLP250 (F) chip structure; the MOS tube Q11 adopts the HYG015N10NS1TA chip structure; the logic output optocoupler chip TLP250 (F) is used to convert the 3.3V PWM wave output by the control module into a 12V PWM wave, isolating the interference of large current on the waveform; the MOS tube chip HYG015N10NS1TA is used to control whether the line from the terminal U2 to the terminal U1 is turned on; the current limiting resistor R2, the anti-breakdown resistor R3 and the diode D1 between the logic output optocoupler G1 and the MOS tube Q11 work together to make the gate G electrode capacitor on the MOS tube Q11 charge and discharge more quickly, so that the MOS tube Q11 is turned off more quickly.

[0012] The single-chip control module is composed of an STM32F103C8T6 core circuit and peripheral circuits, and provides 8-channel PWM waveform control for the TI-TMS drive circuit module.

[0013] The STM32F103C8T6 core circuit is composed of an STM32F103C8T6 chip, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a crystal oscillator Y1, and a crystal oscillator Y2; one end of the capacitor C3 is grounded, and the other end is connected to the PC14 pin of the STM32F103C8T6 chip; one end of the capacitor C4 is grounded, and the other end is connected to the PC15 pin of the STM32F103C8T6 chip; the crystal oscillator Y1 is connected in parallel between the PC14 pin and the PC15 pin of the STM32F103C8T6 chip, and is used to read external sensors. analog signal; one end of the capacitor C6 is grounded, and the other end is connected to the PD0 pin of the STM32F103C8T6 chip; one end of the capacitor C7 is grounded, and the other end is connected to the PD1 pin of the STM32F103C8T6 chip; the crystal oscillator Y2 is connected in parallel between pin PD9 and pin PD1, wherein the PD0 pin can be used as channel 0 of timer 3, i.e. TIM3_CH0, or as PWM output, and the PD1 pin is similar to PD0 and can be used as channel 1 timer of timer 3, i.e. TIM3_CH0, or as PWM output; the capacitor C5 and The reset pin NRST in the STM32F103C8T6 chip is connected in parallel to form a reset circuit. When the pin is pulled low, the microcontroller will reset. It can also be reset manually. The STM32F103C8T6 chip is a microcontroller, which is the core of the single-chip control module and is responsible for processing the logic and control tasks in the circuit, including pins (PA0-PA15, PB0-PB15), reset pin (NRST), GND (ground pin); wherein the pins (PA0-PA15, PB0-PB15) are the input and output pins of the microcontroller. The output pins used in the present invention are PA0, PA1, PA2, PA3, PA6, PA7, PB0, and PB1; the reset pin (NRST) is used to reset the state of the microcontroller; the GND (ground pin) is used to provide a common reference voltage for the circuit; the purpose of the capacitors (C3, C4, C5, C6, and C7) is filtering and decoupling, helping to stabilize the power supply voltage and reduce noise; the purpose of the crystal oscillator (Y1, Y2) is to provide a clock signal to ensure that the microcontroller can run at a stable frequency. Y1 is usually used for a real-time clock (RTC), while Y2 is used for the main clock of the microcontroller.

[0014] The peripheral circuit of the single-chip control module circuit is composed of an ST-LINK connection circuit and a BOOT startup circuit; the ST-LINK connection circuit is composed of a debug interface SWD, a pin PA13 (SWDIO), a pin PA14 (SWCLK), a ground terminal GND, and a pin VSWD; the debug interface SWD's pin 2 is connected to the pin PA14, the pin 4 is connected to the pin PA13, the pins 5 and 6 are connected to the ground terminal GND, and the pins 9 and 10 are connected to the pin VSWD. The purpose of this circuit is to enable the ST-LINK debugger to communicate effectively with the STM32 microcontroller to download, debug and monitor programs; the debug interface SWD is an interface for debugging and programming the STM32 microcontroller, allowing developers to debug and program through a small number of pins; the pin PA13 (SWDIO) is used for data input / output, allowing the debugger to communicate with the microcontroller; the pin PA14 (SWCLK) is used for the clock signal; the ground pin GND acts to provide a common reference voltage for the circuit to ensure the normal operation of the circuit; the pin VSWD is usually used to provide power for the debugger.

[0015] The BOOT startup circuit is composed of pin BOOT0, pin BOOT1, pin PB2, connector Header 3, resistor R5, ground terminal GND, and power supply 3.3V. Figure 5-c As shown; pins 1, 2, and 3 of pin BOOT1 are connected to the ground terminal GND, pin PB2, and power supply 3.3V respectively, pins 1, 2, and 3 of pin BOOT0 are connected to the ground terminal GND, pin BOOT0, and power supply 3.3V respectively, and resistor R5 is connected in parallel to pins 1 and 2. In this circuit, the function of pins BOOT0 and BOOT1 is to select the microcontroller to boot from different memories (such as flash memory or system memory) by setting the levels of these two pins; PB2 is a pin of the microcontroller, usually used to connect to the BOOT1 pin, which can be configured as input or output; Header 3 is a connector, usually used to connect external devices or jumpers to select the status of BOOT0 and BOOT1. By inserting a jumper, the connection status of the pin can be easily changed; resistor R5 is used to pull up or pull down pin BOOT0 to ensure that the pin remains in a stable level state when not connected, which can prevent the pin from floating and causing an uncertain startup mode; GND is a ground pin, which provides a common reference voltage for the circuit to ensure the normal operation of the circuit; 3.3V is a power pin, which provides a 3.3 volt power supply voltage to supply other components in the circuit.

[0016] The STM32F103C8T6 control chip is the core of the entire control module. The chip adopts the Cortex-M3 core, has the characteristics of high performance and low power consumption, and is suitable for real-time processing. Compared with other similar products, the chip has a higher cost performance in terms of price and performance, and supports 64KB of flash memory and 20KB of RAM, which can meet the needs of different projects. The present invention generates 8 PWM waves of different frequencies through this chip; Figure 5-b The core component is the SWD interface, which is mainly used to enable the interaction between the computer and the chip, so that the computer commands are transmitted to the control chip; Figure 5-c The core components in the chip are pins BOOT0 and BOOT1. BOOT0 and BOOT1 are pins used to control the boot mode. By setting the levels of these two pins, the boot mode of the chip can be selected, including booting from Flash, SRAM or system boot program.

[0017] The power supply module is composed of an AMS1 117 chip and peripheral circuits, and is used to provide 3.3V power supply for the single-chip control module and 12V power supply for the logic output optocoupler G1. The AMS1117 has a low voltage difference, built-in overcurrent protection and thermal shutdown functions, and the maximum output current of the chip can reach 1A; the external circuit design is simple and easy to integrate and use.

[0018] The power supply module is composed of a linear regulator U11, a linear regulator U22, a DC power supply, a switch K, a diode D11, a capacitor C11, a capacitor C22, a capacitor C33, a capacitor C44, a light-emitting diode D22, a resistor R11 and a ground GND, and is used to convert the 12V voltage of the DC power supply into the 3.3V voltage required by the single-chip control module and the 12V voltage required by the drive module; Pin 1 of the DC power supply is connected to the switch K, and Pin 3 is grounded, so that the 12V voltage flows into the linear regulator; the diode D11 is connected in series between the switch K and the Vin port of the linear regulator U11, so as to prevent the current from flowing in reverse; the capacitor C11 is connected in parallel between the Vin port and the GND port of the linear regulator U11, so as to filter; the LED The positive terminal of D22 is connected in parallel between the Vout port of the linear regulator U11 and the GND port of the linear regulator U22, in order to observe whether current flows through the circuit, and its negative terminal is connected to one end of the resistor R11; the capacitor C22 is connected in parallel between the Vout port of the linear regulator U11 and the GND port of the linear regulator U22, in order to stabilize the voltage; the capacitor C33 is connected in parallel between the Vin port and the GND port of the linear regulator U22, for filtering and stabilizing the power supply; the capacitor C44 is connected in parallel between the Vout port and the GND port of the linear regulator U22, and its purpose is also to filter and stabilize the power supply. The DC power supply is used to provide the DC voltage required by the circuit; the switch (K) is used to control the on and off of the circuit, the circuit works when it is turned on, and stops working when it is turned off; the diode (D11) is used to prevent the current from flowing in the reverse direction and protect other components in the circuit; the capacitors (C11, C22) are used to smooth the power supply voltage and reduce voltage fluctuations, wherein C11 is used for filtering and C22 is used for stabilizing the voltage; the linear regulators (U1, U2) stabilize the input voltage to +5V and +3.3V respectively, and provide a stable power supply to the subsequent circuit; the LED (D22) is an indicator light, which shows whether the circuit is working normally. When the circuit is powered on, the LED light emitting diode D22 will light up; the resistor (R11) is used to limit the current flowing through the LED light emitting diode D22, protecting the LED light emitting diode D22 from being damaged by excessive current; the capacitors (C33, C44) are used to filter and stabilize the power supply, and reduce power supply noise; the ground (GND) is a common reference point of the circuit, and all voltages are measured relative to the ground. Its driving module, single-chip control module, and power supply module share a ground point.

[0019] The core components of the power supply module are the A1117-3.3 and A1117-5 linear regulators, which convert the 12V voltage into 3.3V and 5V voltages to provide voltage for the drive circuit module and the microcontroller control module.

[0020] The dual-capacitor power supply system is composed of capacitors C1, C2, inductor L1, drive module Q1, drive module Q2, drive module Q3, drive module Q4, control module E1, control module E2, control module E3, control module E4, power supply V1, power supply V2, resistor R4, and resistor R5; the current measurement module is composed of a current transformer XCP1 and an oscilloscope XSC3; the power supply V1 is connected to the drive module Q2 through a current limiting resistor R4, and then connected in parallel with the capacitor C1. The drive module Q2 is connected to the control module E1, and its purpose is to control the charging state of the capacitor C1. The purpose of the resistor R4 is to prevent the charging current from being too large. The power supply V 1 is used to provide voltage to capacitor C1; the inductor L1 is connected to the drive module Q1, and then connected in parallel with the capacitor C1. The drive module Q1 is connected to the control module E2, and its purpose is to control the discharge state of the capacitor C1. The purpose of the inductor L1 is to make the capacitor C1 and the inductor L1 form an underdamped oscillation circuit to generate a sinusoidal current in the inductor; the current transformer XCP1 and the oscilloscope XSC3 are connected in parallel to the inductor L1, and their purpose is to test whether the current waveform and size in the actual coil are consistent with the simulation; the capacitor C1 and the inductor L1 are respectively connected to the drive circuit module terminal U1 and the terminal U2;

[0021] The power supply V2 is connected to the driving module Q4 through the current limiting resistor R5, and then connected in parallel with the capacitor C2. The driving module Q4 is connected to the control module E4 for the purpose of controlling the charging state of the capacitor C2. The purpose of the resistor R5 is to prevent the charging current from being too large. The purpose of the power supply V2 is to provide voltage to the capacitor C2; the inductor L1 is connected to the driving module Q3, and then connected in parallel with the capacitor C2. The driving module Q3 is connected to the control module E3 for the purpose of controlling the discharge state of the capacitor C2 through the control module E3.

[0022] The order of control modules E1, E2, E3 and E4 of the dual-capacitor power supply system must be coordinated with each other to enable continuous sinusoidal current to pass through the inductor L1; the PWM control waveforms of the control modules E1 and E3 are the same, the PWM control waveforms of the control modules E2 and E4 are the same, and the waveforms of the control modules E1, E3 and the control modules E2 and E4 are opposite.

[0023] In order to avoid excessive distortion of the generated sinusoidal current waveform, the order of magnitude of the total impedance between the terminals U1 and U2 in the driving circuit module should be in the milliohm level, and the total impedance includes the welding impedance, the impedance of the PCB board, the impedance of the MOS tube Q11, and the impedance of the terminals U1 and U2 themselves. The driving circuit module uses a double-layer PCB board structure, and the circuit structure of the driving circuit module on each PCB board is the same, and the terminals U1 and U2 are used together. The drain D pole of the MOS tube of the driving circuit module on the PCB board is connected to the terminal U1, and the source S pole is connected to the terminal U2, so that the PCB boards are connected in parallel, that is, the PCB board with the driving module can be connected in parallel through the terminals U1 and U2 to form a new structure, which increases the overcurrent capacity of the PCB board and reduces the total impedance of the PCB board to the milliohm level. If you want to further reduce the impedance, you can achieve it by connecting multiple PCB boards in parallel. The more PCB boards are connected in parallel, the smaller the impedance is, and the heat dissipation and overcurrent capacity of the chip are stronger.

[0024] The working principle of the present invention is as follows: the constant voltage source module converts 220V alternating current into the required direct current, the single-chip control module controls the charging and discharging state of the capacitor and the coil, the drive module makes the control module move more quickly and reduces the interference of large current on the chip, the power supply module provides power for the control module and the drive module, the capacitor and the inductor coil in the dual-capacitor power supply system cooperate with each other to generate a sinusoidal current, and the measurement module uses a current transformer and an oscilloscope to check the waveform and amplitude of the coil current.

[0025] In order to solve the problem that the traditional TMS system has insufficient focusing ability and cannot stimulate specific areas or deep brain areas, the present invention designs and builds a TI-TMS system, which has better stimulation depth and focusing than traditional TMS. Since the current emitted by the traditional TMS system is intermittent, and the TI-TMS system requires the introduction of a continuous sinusoidal current with a certain frequency difference, TI-TMS stimulation cannot be achieved through the discharge circuit of the traditional TMS system. In order to achieve the continuous introduction of high-frequency sinusoidal current, the present invention successfully enables the system to emit high-frequency current through a dual-capacitor power supply circuit.

[0026] In order to enable the control system to quickly and accurately control the frequency of the current, the present invention connects a diode D1 in parallel with R2 of the driving circuit, such as Figure 4 As shown, in this way, the G-pole capacitor of the MOS tube can be quickly charged and discharged, thereby quickly controlling the opening and closing of the MOS tube.

[0027] In order to prevent the large current passing through the D and S poles of the MOS tube from affecting the PWM wave of the control circuit, the present invention connects a logic output optocoupler TLP250 (F) in series with the drive circuit. Figure 4 This can not only isolate the interference of large current on PWM wave, but also further improve the breaking speed of MOS tube.

[0028] In order to realize dual-capacitor power supply, the control signal needs 8-way PWM wave output to control the conduction of the MOS tube, which is 6 more than the traditional TMS, which greatly increases the difficulty of coordination. The present invention realizes 8-way PWM wave output of PA0, PA1, PA2, PA3, PA6, PA7, PB0, PB1 by configuring TIM2 and TIM3 in the program.

[0029] In order to improve the PCB board's ability to handle large currents, this paper proposes a double-layer PCB board structure, such as Figure 8 This can not only increase the current flowing through, but also reduce the internal resistance of the PCB board, reduce the current decay rate, and make the current waveform closer to the ideal sine wave.

[0030] The driving circuit module is used to quickly drive the MOS tube and reduce the impact of high current on the MOS tube control signal. The driving chip selected for this circuit is TLP250 (F), which has the following functions: isolating signals, transmitting signals, amplifying signals, and controlling current. The actual circuit diagram is shown in the figure. Figure 4 As shown. TLP250(F) can electrically isolate the input signal from the output signal to prevent the transmission of electrical noise and electrical interference, thereby improving the stability and reliability of the system. Since the output amplitude of the PWM wave of the control chip is very small, it is not enough to drive the MOS tube to open and close, and TLP250(F) can amplify the output signal by controlling the voltage of the power supply end. Connect the PWM wave to the input end of TLP250(F) and pass a 12V voltage to the power supply end to amplify the output signal of the PWM wave to 12V. In addition, TLP250(F) can also convert the input signal into an optical signal, and convert the optical signal into an output signal through the photodiode in the optical coupling device. When the current at the input end exceeds a certain threshold, it will also limit the current at the output end to protect the circuit from damage by overcurrent.

[0031] In order to realize dual capacitor power supply, the control signal needs 8-way PWM wave output to control the conduction of the MOS tube. Therefore, the control circuit chip used in the control module is STM32F103C8T6, which has a 32-bit ARM Cortex-M3 core, an operating frequency of up to 72MHz, and has high performance and low power consumption. 64KB Flash memory and 20KB SRAM memory can be used to store program code and data, which can achieve a maximum of 30-way PWM output, far meeting the conditions of 8-way output.

[0032] Construction of TI-TMS system: Connect the components in the driving circuit module together through the PCB board. Since the current flowing through the two ends of the MOS tube is a large current, the ordinary PCB board cannot withstand excessive current. This paper proposes a double-layer PCB board structure, which can not only increase the current flowing through, but also reduce the internal resistance of the PCB board, reduce the current attenuation rate, and make the current waveform closer to the ideal sine wave.

[0033] Connect the input end of the terminal block to the constant voltage source through a resistor, and the other end to the capacitor. Connect the input end of the other terminal block to the capacitor, and the other end directly to the inductor. The same is true for the other two. Connect the control circuit to the drive circuit, and you can form a complete TI-TMS system.

[0034] The innovative features of the present invention are as follows:

[0035] Since the current emitted by the traditional TMS system is intermittent and the current attenuation on the inductor coil is large. The current waveform generated by the traditional TMS method cannot generate a modulated wave, and thus TI-TMS cannot be realized. The present invention proposes a dual-capacitor power supply circuit, which solves the problem of being unable to generate continuous sinusoidal current and greatly reduces the current attenuation. In addition, this article turns this method into reality. Through a dual-capacitor power supply circuit, a physical TI-TMS system is successfully produced, and a temperature field simulation is performed. The simulation results show that under the condition of a current of 100A, the temperature rise in 6 minutes is 34.2 degrees Celsius, which is within the safe range of use. Fig. 9 shown.

[0036] Repetitive transcranial magnetic stimulation (rTMS) does not require a continuous sinusoidal current. In fact, the current it generates is a pulsed current, that is, it appears in the form of a series of short pulses rather than a continuous waveform. Taking 10Hz as an example, the current waveform it generates is as follows: Figure 1 As shown. TI-TMS requires continuous high-frequency current, and the waveform it requires is a modulated wave generated by the superposition of two high-frequency currents with a frequency difference. The waveform generated is as follows Figure 2 shown.

[0037] Technical difficulties of the present invention:

[0038] Traditional TMS and TI-TMS have different sensitivities to current decay. Current decay has little effect on traditional TMS, but TI-TMS is very sensitive to current decay. Since the actual generated current will inevitably decay, and an excessively large decay index will cause the modulation waveform of TI-TMS to be distorted, such as Figure 3As shown. In this way, it is necessary to reduce the attenuation index as much as possible, and the factors that affect the attenuation index are r and L, as shown in formula (1). Since L is a fixed value after the coil is determined, it is necessary to reduce the value of r as much as possible.

[0039]

[0040] in is the attenuation index, r is the line impedance, and L is the coil inductance.

[0041] Since the inductance of the coil is at the microhenry level, in order to prevent the attenuation index from causing excessive distortion to the modulated wave, the line impedance needs to be controlled at the milliohm level. This places very strict requirements on the selection and welding of the chip. The present invention successfully reduces the total impedance of the circuit and chip to the milliampere level by selecting the chip and proposing a double-layer PCB board structure. The present invention uses a double-layer PCB board structure. If you want to further reduce the impedance, you can continue to connect PCB boards in parallel. The more PCB boards are connected in parallel, the smaller the impedance is, and the heat dissipation and overcurrent capabilities of the chip are stronger.

[0042] The traditional TMS control circuit only needs to control the opening and closing of 2 switches, while TI-TMS needs to control the opening and closing of 8 switches. This brings great difficulties to the writing of the control chip program. The present invention uses the STM32F103C8T6 chip, and controls the STM32 through the chip program to generate 8-channel PWM wave outputs, which are PA0, PA1, PA2, PA3, PA6, PA7, PB0, and PB1.

[0043] Advantages of the present invention: The stimulation effect of the TI-TMS system of the present invention is better than that of the traditional rTMS; in order to enhance the heat dissipation capacity of the PCB board so that it can pass a larger current, the present invention designs a double-layer PCB structure, and compared with the traditional copper busbar welding method with excessive current, its impedance is greatly reduced. If the performance of the PCB board is to be further improved, the PCB boards can be connected in parallel on the basis of the double-layer PCB board. The more PCB boards are connected in parallel, the better the performance; under the premise of achieving the same stimulation intensity, the energy required by the coil used in the present invention is lower than that of the traditional TMS; the amplitude and frequency are adjustable, and its amplitude and frequency can be changed by modifying the constant voltage source and the control signal.

Brief Description of the Drawings

[0044] Figure 1 Schematic diagram of the current waveform generated by 10 Hz repetitive transcranial magnetic stimulation (rTMS) in the prior art.

[0045] Figure 2 The figure is a schematic diagram of the modulation wave current waveform required for TI-TMS in a transcranial magnetic stimulation system based on time interference involved in the present invention.

[0046] Figure 3 The figure is a schematic diagram of a modulation wave waveform of TI-TMS that is distorted when the current decays (the decay index is set to 5000) in a transcranial magnetic stimulation system based on time interference according to the present invention.

[0047] Figure 4 The present invention is a schematic diagram of the circuit structure of a driving circuit module in a transcranial magnetic stimulation system based on time interference.

[0048] FIG5 is a schematic diagram of the circuit structure of a single-chip control module in a transcranial magnetic stimulation system based on time interference according to the present invention (wherein, Figure 5-a For the STM32F103C8T6 core circuit, Figure 5-b Connect the circuit to ST-LINK. Figure 5-c For the BOOT startup circuit).

[0049] Figure 6 The present invention is a schematic diagram of the circuit structure of a power supply module in a transcranial magnetic stimulation system based on time interference.

[0050] Figure 7 A schematic diagram of the circuit structure of a dual-capacitor power supply system and a current measurement module in a transcranial magnetic stimulation system based on time interference according to the present invention

[0051] Figure 8 Schematic diagram of the double-layer PCB structure of a transcranial magnetic stimulation system based on time interference according to the present invention (wherein, Figure 8 -a is the PCB pattern of a double-layer PCB board, Figure 8 -b is the structural diagram of a double-layer PCB board)

[0052] Fig. 9 It is a schematic diagram of temperature simulation of a coil in a transcranial magnetic stimulation system based on time interference according to the present invention.

[0053] Fig.10 This is a simulation comparison diagram of the stimulation performance of a transcranial magnetic stimulation system based on time interference involved in the present invention and traditional transcranial magnetic stimulation.

[0054] Fig.11 This is an overall structural block diagram of a transcranial magnetic stimulation system based on time interference involved in the present invention.

[0055] Fig.12 Schematic diagram of waveforms of coil current in simulation and practice in a transcranial magnetic stimulation system based on time interference according to the present invention (wherein, Fig.12 -a is a schematic diagram of the simulation results of the coil current, Fig.12 -b is a schematic diagram of the experimental results of coil current). [Specific implementation method]

[0056] Embodiment: A transcranial magnetic stimulation system based on time interference, such as Fig.11 As shown, it is characterized in that it includes a constant voltage source module, a single-chip control module, a driving circuit module, a power supply module, a dual-capacitor power supply system and a current measurement module; wherein the constant voltage source module is connected to the driving circuit module; the power supply module provides working power for the single-chip control module and the driving circuit module; the output end of the single-chip control module is connected to the input end of the driving circuit module; the input end of the dual-capacitor power supply system is connected to the driving circuit module, and its output end is connected to the current testing module.

[0057] The constant voltage source module is composed of the Maisheng MS1520DS constant voltage source, which is used to provide the required voltage for the TI-TMS system. Since it can achieve continuously adjustable voltage of 0-30V and current of 0-60A with resolutions of 10mV and 10mA respectively, the stimulation intensity of TI-TMS can be changed by only changing the voltage of the constant voltage source.

[0058] like Figure 4 As shown, the driving circuit module is used to correctly switch the circuit mode according to the requirements of the control signal, so that the capacitor is continuously charged and discharged to generate a continuous sinusoidal current, and is composed of a logic output optocoupler G1, a MOS tube Q11 and a peripheral circuit; the logic output optocoupler G1 is used to isolate the large current signal at both ends of the MOS tube Q11 to prevent the large current signal from interfering with the control signal and causing inaccurate action, and at the same time amplify the control signal sent by the single-chip control module (STM32F103C8T6) to make the MOS tube Q11 act more quickly; the MOS tube Q11 is used to correctly switch the circuit mode according to the control signal of the single-chip control module to correctly generate a continuous sinusoidal current.

[0059] like Figure 4As shown, the driving circuit module is specifically composed of a pin header H1, a pin header H2, a pin header H3, a current limiting resistor R1, a logic output optocoupler G1, a current limiting resistor R2, a diode D1, an anti-breakdown resistor R3, a MOS tube Q11, a wiring terminal U1, and a wiring terminal U2; the 1 terminal of the pin header H1 is connected to the AN terminal of the logic output optocoupler G1 through the current limiting resistor R1, wherein the purpose of the current limiting resistor R1 is to limit the current flowing into the logic output optocoupler G1 to prevent the logic output optocoupler G1 from being damaged by excessive current; the 2 terminal of the pin header H1 is connected to the CAT terminal of the logic output optocoupler G1, and its purpose is to form a loop with the pin header H1, the current limiting resistor R1, and the logic output optocoupler G1 so that the control signal passes through the pin header H1. The current flows into the logic output optocoupler G1 through the pin H1; the pin H2 is connected to the VCC end of the logic output optocoupler G1, in order to pass the power to the logic output optocoupler G1 through H2; the GND end of the logic output optocoupler G1 is grounded through the pin H3; the VO end of the logic output optocoupler G1 is connected in series to the gate G pole of the MOS tube Q11 through the current limiting resistor R2; the diode D1 is reversely connected in parallel to the current limiting resistor R2, so that the control signal amplified by the logic output optocoupler G1 is transmitted to the G pole of the MOS tube Q11; the current limiting resistor R2 is used to limit the current flowing into the MOS tube Q11 to prevent the MOS tube Q11 from being damaged by excessive current; the diode D1 is used to make the source-gate capacitor C on the MOS tube Q11 gs Rapid charging and discharging makes the MOS tube Q11 turn off more quickly; the two ends of the anti-breakdown resistor R3 are connected to the gate G pole and the source S pole of the MOS tube Q11, and its purpose is to prevent the MOS tube from being broken down when it is turned on without driving; one end of the wiring terminal U1 and the wiring terminal U2 are respectively connected to the drain D pole and the source S pole of the MOS tube Q11, and the other ends of the wiring terminal U1 and the wiring terminal U2 are respectively connected to the dual-capacitor power supply system, so that the MOS tube Q11 can correctly switch the circuit mode of the dual-capacitor power supply system.

[0060] like Figure 4 As shown, the core components of the driving circuit module are the logic output optocoupler G1 and the MOS tube Q11; wherein the logic output optocoupler adopts the TLP250 (F) chip structure; the MOS tube Q11 adopts the HYG015N10NS1TA chip structure; the logic output optocoupler chip TLP250 (F) is used to convert the 3.3V PWM wave output by the control module into a 12V PWM wave, isolating the interference of the large current on the waveform; the MOS tube chip HYG015N10NS1TA is used to control whether the line from the terminal U2 to the terminal U1 is turned on; the current limiting resistor R2, the anti-breakdown resistor R3 and the diode D1 between the logic output optocoupler G1 and the MOS tube Q11 work together to make the gate G electrode capacitor on the MOS tube Q11 charge and discharge more quickly, so that the MOS tube Q11 is turned off more quickly.

[0061] like Figure 5-a As shown, the single-chip control module is composed of the STM32F103C8T6 core circuit and peripheral circuits, providing 8-channel PWM waveform control for the TI-TMS drive circuit module.

[0062] like Figure 5-a As shown in the figure, the STM32F103C8T6 core circuit is composed of an STM32F103C8T6 chip, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, a crystal oscillator Y1, and a crystal oscillator Y2; one end of the capacitor C3 is grounded, and the other end is connected to the PC14 pin of the STM32F103C8T6 chip; one end of the capacitor C4 is grounded, and the other end is connected to the PC15 pin of the STM32F103C8T6 chip; the crystal oscillator Y1 is connected in parallel between the PC14 pin and the PC15 pin of the STM32F103C8T6 chip, and is used to read the analog of the external sensor. The analog signal; one end of the capacitor C6 is grounded, and the other end is connected to the PD0 pin of the STM32F103C8T6 chip; one end of the capacitor C7 is grounded, and the other end is connected to the PD1 pin of the STM32F103C8T6 chip; the crystal oscillator Y2 is connected in parallel between the pin PD9 and the pin PD1, wherein the PD0 pin can be used as the channel 0 of the timer 3, that is, TIM3_CH0, and can also be used as a PWM output, and the PD1 pin is similar to PD0 and can be used as the channel 1 timer of the timer 3, that is, TIM3_CH0, and can also be used as a PWM output; the capacitor C5 is connected to the STM32F1 The reset pin NRST in the 03C8T6 chip is connected in parallel to form a reset circuit, which functions to reset the microcontroller when the pin is pulled low, and can also be reset by manual triggering; the STM32F103C8T6 chip is a microcontroller, which is the core of the single-chip control module and is responsible for processing the logic and control tasks in the circuit, including pins (PA0-PA15, PB0-PB15), a reset pin (NRST), and GND (ground pin); wherein the pins (PA0-PA15, PB0-PB15) are the input and output pins of the microcontroller, and the output pins used in the present invention are PA0, PA1, PA2, PA3, PA6, PA7, PB0, PB1; the reset pin (NRST) is used to reset the state of the microcontroller; the GND (ground pin) is used to provide a common reference voltage for the circuit; the purpose of the capacitors (C3, C4, C5, C6, C7,) is filtering and decoupling, helping to stabilize the power supply voltage and reduce noise; the purpose of the crystal oscillator (Y1, Y2) is to provide a clock signal to ensure that the microcontroller can run at a stable frequency, Y1 (32.768kHz) is usually used for the real-time clock (RTC), and Y2 (8MHz) is used for the main clock of the microcontroller.

[0063] The peripheral circuit of the single-chip control module circuit is composed of an ST-LINK connection circuit and a BOOT startup circuit. Figure 5-b , 5-c As shown; the ST-LINK connection circuit consists of a debug interface SWD, pin PA13 (SWDIO), pin PA14 (SWCLK), ground terminal GND, and pin VSWD; pin 2 of the debug interface SWD is connected to pin PA14, pin 4 is connected to pin PA13, pins 5 and 6 are connected to the ground terminal GND, and pins 9 and 10 are connected to pin VSWD. The purpose of this circuit is to enable the ST-LINK debugger to communicate effectively with the STM32 microcontroller to download, debug and monitor programs; the debug interface SWD is an interface for debugging and programming the STM32 microcontroller, allowing developers to debug and program through a small number of pins; pin PA13 (SWDIO) is used for data input / output, allowing the debugger to communicate with the microcontroller; pin PA14 (SWCLK) is used for clock signals; the ground pin GND is used to provide a common reference voltage for the circuit to ensure the normal operation of the circuit; pin VSWD is usually used to provide power for the debugger.

[0064] The BOOT startup circuit is composed of pin BOOT0, pin BOOT1, pin PB2, connector Header 3, resistor R5 (10KΩ in the embodiment), ground terminal GND, and power supply 3.3V. Figure 5-c As shown; pins 1, 2, and 3 of pin BOOT1 are connected to the ground terminal GND, pin PB2, and power supply 3.3V respectively, pins 1, 2, and 3 of pin BOOT0 are connected to the ground terminal GND, pin BOOT0, and power supply 3.3V respectively, and resistor R5 is connected in parallel to pins 1 and 2. In this circuit, the function of pins BOOT0 and BOOT1 is to select the microcontroller to boot from different memories (such as flash memory or system memory) by setting the levels of these two pins; PB2 is a pin of the microcontroller, usually used to connect to the BOOT1 pin, which can be configured as input or output; Header 3 is a connector, usually used to connect external devices or jumpers to select the status of BOOT0 and BOOT1. By inserting a jumper, the connection status of the pin can be easily changed; resistor R5 is used to pull up or pull down pin BOOT0 to ensure that the pin remains in a stable level state when not connected, which can prevent the pin from floating and causing an uncertain startup mode; GND is a ground pin, which provides a common reference voltage for the circuit to ensure the normal operation of the circuit; 3.3V is a power pin, which provides a 3.3 volt power supply voltage to supply other components in the circuit.

[0065] Figure 5-aThe core component STM32F103C8T6 control chip is also the core of the entire control module. The chip adopts the Cortex-M3 core, has the characteristics of high performance and low power consumption, and is suitable for real-time processing. Compared with other similar products, the chip has a higher cost performance in terms of price and performance, and supports 64KB of flash memory and 20KB of RAM, which can meet the needs of different projects. The present invention generates 8 PWM waves of different frequencies through this chip; Figure 5-b The core component is the SWD interface, which is mainly used to enable the interaction between the computer and the chip, so that the computer commands are transmitted to the control chip; Figure 5-c The core components in the chip are pins BOOT0 and BOOT1. BOOT0 and BOOT1 are pins used to control the boot mode. By setting the levels of these two pins, the boot mode of the chip can be selected, including booting from Flash, SRAM or system boot program.

[0066] The power supply module is composed of an AMS1 117 chip and peripheral circuits, and is used to provide 3.3V power supply for the single-chip control module and 12V power supply for the logic output optocoupler G1. The AMS1117 has a low voltage difference, built-in overcurrent protection and thermal shutdown functions, and the maximum output current of the chip can reach 1A; the external circuit design is simple and easy to integrate and use.

[0067] like Figure 6As shown, the power supply module is composed of a linear regulator U11, a linear regulator U22, a DC power supply, a switch K, a diode D11, a capacitor C11, a capacitor C22, a capacitor C33, a capacitor C44, a light-emitting diode D22, a resistor R11 and a ground GND, and is used to convert the 12V voltage of the DC power supply into the 3.3V voltage required by the single-chip control module and the 12V voltage required by the drive module; the pin 1 of the DC power supply is connected to the switch K, and the pin 3 is grounded, so that the 12V voltage flows into the linear regulator; the diode D11 is connected in series between the switch K and the Vin port of the linear regulator U11, so as to prevent the current from flowing in reverse; the capacitor C11 is connected in parallel to the V in port and GND port for filtering; the positive terminal of the LED D22 is connected in parallel between the Vout port of the linear regulator U11 and the GND port of the linear regulator U22 for observing whether current flows through the circuit, and its negative terminal is connected to one end of the resistor R11; the capacitor C22 is connected in parallel between the Vout port of the linear regulator U11 and the GND port of the linear regulator U22 for stabilizing the voltage; the capacitor C33 is connected in parallel between the Vin port and the GND port of the linear regulator U22 for filtering and stabilizing the power supply; the capacitor C44 is connected in parallel between the Vout port and the GND port of the linear regulator U22 for filtering and stabilizing the power supply. The DC power supply is used to provide the DC voltage required by the circuit; the switch (K) is used to control the on and off of the circuit, the circuit works when it is turned on, and stops working when it is turned off; the diode (D11) is used to prevent the current from flowing in the reverse direction and protect other components in the circuit; the capacitors (C11, C22) are used to smooth the power supply voltage and reduce voltage fluctuations, wherein C11 is used for filtering and C22 is used for stabilizing the voltage; the linear regulators (U1, U2) stabilize the input voltage to +5V and +3.3V respectively, and provide a stable power supply to the subsequent circuit; the LED (D22) is an indicator light, which shows whether the circuit is working normally. When the circuit is powered on, the LED light emitting diode D22 will light up; the resistor (R11) is used to limit the current flowing through the LED light emitting diode D22, protecting the LED light emitting diode D22 from being damaged by excessive current; the capacitors (C33, C44) are used to filter and stabilize the power supply, and reduce power supply noise; the ground (GND) is a common reference point of the circuit, and all voltages are measured relative to the ground. Its driving module, single-chip control module, and power supply module share a ground point.

[0068] Figure 6 The core components of the power supply module are the A1117-3.3 and A1117-5 linear regulators, which convert the 12V voltage into 3.3V and 5V voltages to provide voltage for the drive circuit module and the microcontroller control module.

[0069] like Figure 7 As shown, the dual-capacitor power supply system consists of capacitors C1, C2, inductor L1, drive module Q1, drive module Q2, drive module Q3, drive module Q4, control module E1, control module E2, control module E3, control module E4, power supply V1, power supply V2, resistor R4, and resistor R5; the current measurement module consists of a current transformer XCP1 and an oscilloscope XSC3; the power supply V1 is connected to the drive module Q2 through a current limiting resistor R4, and then connected in parallel with the capacitor C1. The drive module Q2 is connected to the control module E1, and its purpose is to control the charging state of the capacitor C1. The purpose of the resistor R4 is to prevent the charging current from being too large. The purpose of the source V1 is to provide voltage to the capacitor C1; the inductor L1 is connected to the drive module Q1, and then connected in parallel with the capacitor C1. The drive module Q1 is connected to the control module E2, and its purpose is to control the discharge state of the capacitor C1. The purpose of the inductor L1 is to make the capacitor C1 and the inductor L1 form an underdamped oscillation circuit to generate a sinusoidal current in the inductor; the current transformer XCP1 and the oscilloscope XSC3 are connected in parallel to the inductor L1, and their purpose is to test whether the current waveform and size in the actual coil are consistent with the simulation; the capacitor C1 and the inductor L1 are respectively connected to the drive circuit module terminal U1 and the terminal U2;

[0070] The power supply V2 is connected to the driving module Q4 through the current limiting resistor R5, and then connected in parallel with the capacitor C2. The driving module Q4 is connected to the control module E4, and its purpose is to control the charging state of the capacitor C2. The purpose of the resistor R5 is to prevent the charging current from being too large. The purpose of the power supply V2 is to provide voltage to the capacitor C2; the inductor L1 is connected to the driving module Q3, and then connected in parallel with the capacitor C2. The driving module Q3 is connected to the control module E3, and its purpose is to control the discharge state of the capacitor C2 through the control module E3.

[0071] The order of control modules E1, E2, E3 and E4 of the dual-capacitor power supply system must be coordinated with each other to enable continuous sinusoidal current to pass through the inductor L1; the PWM control waveforms of the control modules E1 and E3 are the same, the PWM control waveforms of the control modules E2 and E4 are the same, and the waveforms of the control modules E1, E3 and the control modules E2 and E4 are opposite. Taking the generation of 1000 Hz sinusoidal current as an example, the frequencies of E1, E2, E3, and E4 are all half the frequency of the sinusoidal current (500 Hz). When the waveforms of E1 and E3 are positive and the waveforms of E2 and E4 are negative, capacitor C1 is connected to power supply V1 and disconnected from inductor L1, capacitor C1 is in a charging state, capacitor C2 is disconnected from power supply V2 and connected to inductor L1, capacitor C2 is in a discharging state, inductor L1 and capacitor C2 form an underdamped oscillation circuit, and a sinusoidal current is generated in inductor L1; when the waveforms of E1 and E3 are negative and the waveforms of E2 and E4 are positive, inductor L1 and capacitor C1 form an underdamped oscillation circuit, and a sinusoidal current is generated in inductor L1.

[0072] In order to avoid excessive distortion of the generated sinusoidal current waveform, the order of magnitude of the total impedance between the terminals U1 and U2 in the driving circuit module should be in the milliohm level, and the total impedance includes the welding impedance, the impedance of the PCB board, the impedance of the MOS tube Q11, and the impedance of the terminals U1 and U2 themselves. In this embodiment, the driving circuit module uses a double-layer PCB board structure, and the PCB board corresponding to the driving module is connected in parallel through the terminals U1 and U2, which increases the overcurrent capacity of the PCB board and reduces the total impedance of the PCB board to the milliohm level. If you want to further reduce the impedance, you can achieve it by connecting multiple PCB boards in parallel. The more PCB boards are connected in parallel, the smaller the impedance, and the stronger the chip heat dissipation and overcurrent capacity. Taking the driving circuit module structure composed of four layers of PCB boards as an example, its impedance will become smaller than that of the double-layer PCB board structure, and the chip heat dissipation and overcurrent capacity will be stronger. The four PCB boards are respectively PCB board I, PCB board II, PCB board III, and PCB board IV. The circuit structures of the driving circuit modules on the four PCB boards are the same, and the connection terminals U1 and U2 are used in common. The drain D pole of the MOS tube of the driving circuit module on PCB board I, PCB board II, PCB board III, and PCB board IV is connected to the connection terminal U1, and the source S pole is connected to the connection terminal U2, so that the four PCB boards are connected in parallel.

[0073] Since repetitive transcranial magnetic stimulation (rTMS) does not require a continuous sinusoidal current, it appears as a series of short pulses rather than a continuous waveform such as Figure 1As shown, TI-TMS requires continuous high-frequency current, and the waveform it requires is a modulated wave generated by the superposition of two high-frequency currents with a frequency difference. The waveform generated is as follows Figure 2 As shown in the figure, TI-TMS stimulation cannot be achieved through the TMS stimulation system currently available on the market. Since TI-TMS is very sensitive to current decay, a large decay index will cause the modulation waveform of TI-TMS to be distorted, such as Figure 3 As shown, it is necessary to reduce the attenuation exponent as much as possible when designing the system.

[0074] The invention of this paper requires two sets of dual-capacitor power supply circuits, one set emits a 1000Hz current waveform, and the other set emits a 1020Hz current waveform. The implementation schemes of the two sets are the same, except that the capacitance of the capacitor and the frequency of the PWM wave emitted by the control chip are different. This time, only one set is used as an example: the overall framework diagram is as follows Fig.11 As shown, the input end of the constant voltage source module is connected to 220V, and the output end is connected to one end of the double-layer PCB board in the driving circuit module. The other end of the double-layer PCB board is connected to the positive electrode of the capacitor in the dual-capacitor power supply system, and the driving circuit module H1 and the single-chip control module PA0 are connected. In this way, the MOS tube can be controlled by the control chip to control the opening and closing of the MOS tube, thereby controlling the charging and discharging of the capacitor. Figure 6 The 12V and 3.3V terminals in the power supply module shown are respectively Figure 4 The drive circuit module shown in Figure 1 shows H2 and Figure 5-c The 3.3V terminal of the microcontroller control module is shown. The negative electrode of the capacitor in the dual-capacitor power supply system is connected to one end of the coil, and the other end of the coil is connected to the negative electrode of the constant voltage source module, so that the entire system can generate a continuous high-frequency sinusoidal current. The amplitude of the coil current can be adjusted by adjusting the output voltage of the constant voltage source module, and the frequency of the coil current can be changed by adjusting the PWM waveform frequency emitted by the microcontroller control module.

[0075] The coil used in the present invention is applicable to rodents, which require much smaller magnetic field and electric field strengths than humans. Stimulation can be achieved when the magnetic field strength is 1V / m. When the coil is fed with a current of 100A, the maximum induced electric field value is 2.12V / m, which meets the stimulation threshold. Fig. 9 As shown in the simulation of the coil temperature, it can be seen that when a current of 100A flows through the coil, the temperature rises from 20°C to 54.2°C in 6 minutes, which is within the temperature range of safe use, further proving the feasibility of the present invention. Fig.10 As shown in the figure, the stimulation intensity and depth of TI-TMS are greater than those of traditional TMS, and the focal area is smaller than that of traditional TMS. The smaller the focal area, the better the focusing performance. Through simulation comparison, it can be concluded that the stimulation performance of TI-TMS is better than that of traditional TMS. Fig.12 Among them, Fig.12 -a is the schematic diagram of coil current obtained through simulation, Fig.12 -b is a schematic diagram of the coil current of the actual system. The present invention compares the current waveform of the coil simulation with the current waveform emitted by the actual coil. Through the comparison, it can be concluded that the current waveform results of the simulation and the actual object are consistent, which further proves the correctness of the TI-TMS stimulation system.

Claims

1. A transcranial magnetic stimulation system based on time interference, characterized in that It includes a constant voltage source module, a single-chip control module, a driving circuit module, a power supply module, a dual-capacitor power supply system and a current measurement module; wherein the constant voltage source module is connected to the driving circuit module; the power supply module provides working power for the single-chip control module and the driving circuit module; the output end of the single-chip control module is connected to the input end of the driving circuit module; the input end of the dual-capacitor power supply system is connected to the driving circuit module, and its output end is connected to the current test module.

2. A transcranial magnetic stimulation system based on time interference according to claim 1, characterized in that The constant voltage source module is composed of a constant voltage source MS1520DS, which provides the required voltage for the TI-TMS system. The stimulation intensity of the TI-TMS can be changed by changing the voltage of the constant voltage source.

3. A transcranial magnetic stimulation system based on time interference according to claim 1, characterized in that The driving circuit module includes a logic output optocoupler G1, a MOS tube Q11 and a peripheral circuit, specifically composed of a pin header H1, a pin header H2, a pin header H3, a current limiting resistor R1, a logic output optocoupler G1, a current limiting resistor R2, a diode D1, an anti-breakdown resistor R3, a MOS tube Q11, a wiring terminal U1, and a wiring terminal U2; the 1 terminal of the pin header H1 is connected to the AN terminal of the logic output optocoupler G1 through the current limiting resistor R1; the 2 terminal of the pin header H1 is connected to the CAT terminal of the logic output optocoupler G1, and the pin header H1, the current limiting resistor R1, and the logic output optocoupler G1 form a loop, so that the control signal flows into the logic output optocoupler G1 through the pin header H1; the pin header H2 is connected to the VCC terminal of the logic output optocoupler G1; The GND end of the logic output optocoupler G1 is grounded through the pin header H3; the VO end of the logic output optocoupler G1 is connected in series to the gate G of the MOS tube Q11 through the current limiting resistor R2; the diode D1 is connected in reverse parallel to the current limiting resistor R2, so that the control signal amplified by the logic output optocoupler G1 is transmitted to the G of the MOS tube Q11; the two ends of the anti-breakdown resistor R3 are connected to the gate G and the source S of the MOS tube Q11; one end of the wiring terminal U1 and the wiring terminal U2 are respectively connected to the drain D and the source S of the MOS tube Q11, and the other ends of the wiring terminal U1 and the wiring terminal U2 are respectively connected to the dual-capacitor power supply system, so that the MOS tube Q11 can correctly switch the circuit mode of the dual-capacitor power supply system.

4. A transcranial magnetic stimulation system based on time interference according to claim 3, characterized in that The logic output optocoupler of the drive circuit module adopts the TLP250 (F) chip structure; the MOS tube Q11 adopts the HYG015N10NS1TA chip structure; the logic output optocoupler chip TLP250 (F) is used to convert the 3.3V PWM wave output by the control module into a 12V PWM wave, isolating the interference of large current on the waveform; the MOS tube chip HYG015N10NS1TA is used to control whether the line from the terminal U2 to the terminal U1 is conductive; the current limiting resistor R2, the anti-breakdown resistor R3 and the diode D1 between the logic output optocoupler G1 and the MOS tube Q11 work together to make the gate G electrode capacitor on the MOS tube Q11 charge and discharge more quickly, so that the MOS tube Q11 is disconnected more quickly.

5. A transcranial magnetic stimulation system based on time interference according to claim 4, characterized in that The driving circuit module adopts a double-layer PCB board structure, which is composed of two PCB boards with the same structure, which are connected in parallel through connection terminals U1 and U2.

6. A transcranial magnetic stimulation system based on time interference according to claim 1, characterized in that The single-chip control module is composed of the STM32F103C8T6 core circuit and peripheral circuits, providing 8-way PWM waveform control for the TI-TMS drive circuit module; the STM32F103C8T6 core circuit is composed of the STM32F103C8T6 chip, capacitor C3, capacitor C4, capacitor C5, capacitor C6, capacitor C7, crystal oscillator Y1, and crystal oscillator Y2; one end of the capacitor C3 is grounded, and the other end is connected to the PC14 pin of the STM32F103C8T6 chip; one end of the capacitor C4 is grounded, and the other end is connected to the PC15 pin of the STM32F103C8T6 chip; the crystal oscillator Y1 is connected in parallel between the PC14 pin and the PC15 pin of the STM32F103C8T6 chip, and is used to read the analog Signal; one end of the capacitor C6 is grounded, and the other end is connected to the PD0 pin of the STM32F103C8T6 chip; one end of the capacitor C7 is grounded, and the other end is connected to the PD1 pin of the STM32F103C8T6 chip; the crystal oscillator Y2 is connected in parallel between the pin PD9 and the pin PD1, wherein the PD0 pin can be used as the channel 0 of the timer 3, i.e. TIM3_CH0, or as a PWM output, and the PD1 pin is similar to PD0 and can be used as the channel 1 timer of the timer 3, i.e. TIM3_CH0, or as a PWM output; the capacitor C5 is connected in parallel with the reset pin NRST in the STM32F103C8T6 chip to form a reset circuit, which functions to reset the microcontroller when the pin is pulled low, and can also be reset by manual triggering; The peripheral circuit of the single-chip control module circuit is composed of an ST-LINK connection circuit and a BOOT startup circuit; the ST-LINK connection circuit is composed of a debugging interface SWD, a pin PA13, a pin PA14, a ground terminal GND, and a pin VSWD; pin 2 of the debugging interface SWD is connected to pin PA14, pin 4 is connected to pin PA13, pins 5 and 6 are connected to the ground terminal GND, and pins 9 and 10 are connected to pin VSWD.

7. A transcranial magnetic stimulation system based on time interference according to claim 6, characterized in that The BOOT startup circuit is composed of pin BOOT0, pin BOOT1, pin PB2, connector Header 3, resistor R5, ground terminal GND, and power supply 3.3V; pin 1, pin 2, and pin 3 in pin BOOT1 are respectively connected to the ground terminal GND, pin PB2, and power supply 3.3V, pin 1, pin 2, and pin 3 in pin BOOT0 are respectively connected to the ground terminal GND, pin BOOT0, and power supply 3.3V, and resistor R5 is connected in parallel to pin 1 and pin 2.

8. A transcranial magnetic stimulation system based on time interference according to claim 6, characterized in that The power supply module includes an AMS1117 chip and peripheral circuits, specifically, a linear regulator U11, a linear regulator U22, a DC power supply, a switch K, a diode D11, a capacitor C11, a capacitor C22, a capacitor C33, a capacitor C44, a light-emitting diode D22, a resistor R11 and a ground GND, and is used to convert the 12V voltage of the DC power supply into the 3.3V voltage required by the single-chip control module and the 12V voltage required by the drive module; pin 1 of the DC power supply is connected to the switch K, and pin 3 is grounded; the diode D11 is connected in series between the switch K and the Vin port of the linear regulator U11; the capacitor C11 is connected in parallel between the Vin port and the GND port of the linear regulator U11; the LED The positive terminal of D22 is connected in parallel between the Vout port of the linear regulator U11 and the GND port of the linear regulator U22, and the negative terminal thereof is connected to one end of the resistor R11; the capacitor C22 is connected in parallel between the Vout port of the linear regulator U11 and the GND port of the linear regulator U22; the capacitor C33 is connected in parallel between the Vin port and the GND port of the linear regulator U22; the capacitor C44 is connected in parallel between the Vout port and the GND port of the linear regulator U22.

9. A transcranial magnetic stimulation system based on time interference according to claim 3, characterized in that The dual-capacitor power supply system is composed of capacitors C1, C2, inductor L1, drive module Q1, drive module Q2, drive module Q3, drive module Q4, control module E1, control module E2, control module E3, control module E4, power supply V1, power supply V2, resistor R4, and resistor R5; the current measurement module is composed of a current transformer XCP1 and an oscilloscope XSC3; the power supply V1 is connected to the drive module Q2 through a current limiting resistor R4, and then connected in parallel with the capacitor C1, and the drive module Q2 is connected to the control module E1; the inductor L1 is connected to the drive module The drive module Q1 is connected to the circuit block, and then connected to the capacitor C1 in parallel, and the drive module Q1 is connected to the control module E2; the current transformer XCP1 and the oscilloscope XSC3 are connected in parallel to the inductor L1; the capacitor C1 and the inductor L1 are respectively connected to the drive circuit module terminal U1 and the terminal U2; the power supply V2 is connected to the drive module Q4 through the current limiting resistor R5, and then connected to the capacitor C2 in parallel, and the drive module Q4 is connected to the control module E4; the inductor L1 is connected to the drive module Q3, and then connected to the capacitor C2 in parallel, and the drive module Q3 is connected to the control module E3.

10. A transcranial magnetic stimulation system based on time interference according to claim 9, characterized in that The order of the control modules E1, E2, E3 and E4 of the dual-capacitor power supply system must be coordinated with each other to achieve the continuous sinusoidal current passing through the inductor L1, that is, the PWM control waveforms of the control modules E1 and E3 are the same, the PWM control waveforms of the control modules E2 and E4 are the same, and the waveforms of the control modules E1, E3 and E2, E4 are opposite; in order to avoid excessive distortion of the generated sinusoidal current waveform, the connection terminals U1 and U2 in the drive circuit module are connected to the drive circuit module. The order of magnitude of the total impedance should be in the milliohm level, and the total impedance includes the welding impedance, the impedance of the PCB board, the impedance of the MOS tube Q11, and the impedance of the wiring terminal U1 and the wiring terminal U2 themselves; the driving circuit module uses a PCB board structure of at least two layers, the circuit structure of the driving circuit module on each PCB board is the same, and the wiring terminal U1 and the wiring terminal U2 are used together, and the drain D pole of the MOS tube of the driving circuit module on each PCB board is connected to the wiring terminal U1, and the source S pole is connected to the wiring terminal U2, so that the PCB boards are connected in parallel.

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