A transcranial electrical stimulation system capable of being used synchronously in a magnetic resonance environment

Abstract

The present application relates to a kind of transcranial electrical stimulation system capable of being used in magnetic resonance environment synchronously.The present application includes electrical stimulation instrument, fluorescent thermometer and nuclear magnetic compatible kit, the electrical stimulation instrument is connected nuclear magnetic compatible kit by first coaxial cable, the nuclear magnetic compatible kit is connected stimulation electrode in nuclear magnetic resonance instrument by second coaxial cable and third coaxial cable, the fluorescent thermometer is connected stimulation electrode in the nuclear magnetic resonance instrument by optical fiber.The present application can be in the process of tDCS stimulation and after stimulation stops to the subject for magnetic resonance scanning, analysis stimulation to brain, functional magnetic resonance imaging (fMRI) technology has higher spatial resolution, can observe the influence of transcranial electrical stimulation to brain in the process and after electrical stimulation, can better study the mechanism of transcranial electrical stimulation;It has important influence to the basic mechanism research of tDCS, simple operation.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically a transcranial electrical stimulation system that can be used synchronously in a magnetic resonance environment. Background Technology

[0002] With the development of modern science and technology, people are paying increasing attention to their health, and clinical medicine is making rapid progress in the diagnosis, monitoring, and treatment of various diseases. From the perspective of biomedical engineering, various neurophysiological instruments are constantly being optimized. Transcranial electrical stimulation (tES) is a non-invasive brain stimulation method that uses low-intensity current (usually 0.5–2 mA) to stimulate target areas of the cerebral cortex, thereby regulating the excitability of neurons in the cerebral cortex, promoting neural remodeling and repair, and improving cerebral blood supply—a non-invasive neuromodulation technique.

[0003] Transcranial electrical stimulation (tDCS) includes transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial random noise stimulation (tRNS). Currently, the application of tDCS technology in the field of neurorehabilitation is gradually being promoted. Related studies have found that it has different therapeutic effects on post-stroke limb motor disorders, cognitive impairment, aphasia, and Parkinson's disease, showing great promise in the field of neurorehabilitation. To date, there are many clinical application experiments of tDCS both domestically and internationally, but relatively few instrument development projects. The main companies developing transcranial direct current stimulators abroad are Soterix Medical in the United States and NeuroConn in Germany. These two companies have relatively advanced stimulators, but they are expensive. There are very few companies in China developing transcranial direct current stimulators; most of them produce simple devices based on research needs.

[0004] Currently, there are numerous studies on the therapeutic effects of tDCS on neuropsychiatric disorders and on healthy individuals, with many publications reporting relevant research results. However, most studies focus on the effects on the brain some time after tDCS stimulation. The mechanism of action of tDCS is complex and not yet fully understood. Regarding the immediate effects of tDCS, i.e., its fundamental mechanism, collecting EEG signals or performing MRI scans after stimulating subjects in experiments cannot accurately reveal its basic mechanism of action. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the technical problem to be solved by the present invention is to provide a transcranial electrical stimulation system that can be used synchronously in a magnetic resonance environment.

[0006] The technical solution adopted by the present invention to achieve the above objectives is: a transcranial electrical stimulation system that can be used synchronously in a magnetic resonance environment, comprising an electrical stimulator, a fluorescence thermometer, and an MRI-compatible kit. The electrical stimulator is connected to the MRI-compatible kit via a first coaxial cable. The MRI-compatible kit is connected to the stimulation electrodes in the MRI machine via a second coaxial cable and a third coaxial cable. The fluorescence thermometer is connected to the stimulation electrodes in the MRI machine via an optical fiber.

[0007] The electrical stimulator includes a current source module, a microprocessor control module, an LCD control module, and a current source module; the current source module is connected to the microprocessor control module, the LCD control module, and the current source module, and is used to provide operating voltage; the microprocessor control module is connected to the LCD control module and the current source module, and is used to control the current output of the current source module and control the operation and display of the LCD control module; the LCD control module is used to connect to an LCD screen; the current source module is used to connect to an NMR-compatible kit via a first coaxial cable.

[0008] The current source module includes a lithium battery charging module and a voltage conversion module. The lithium battery charging module is connected to a rechargeable lithium battery, and the voltage conversion module is used to convert the voltage of the rechargeable lithium battery into the power supply voltage of the microprocessor control module, the LCD control module, and the current source module.

[0009] The current source module includes a voltage buffer module, a differential proportional calculation module, and a current output module; the input terminal of the voltage buffer module is connected to the microprocessor control module, and the output terminal is connected to the differential proportional calculation module; the output terminal of the differential proportional calculation module is connected to the current output module; the current output module is used to connect to the NMR compliant kit via a first coaxial cable.

[0010] The first coaxial cable comprises four layers, from the inside out: an inner conductor, an insulator, an outer conductor, and a sheath. The inner conductor at one end of the first coaxial cable is connected to the current source module of the electrical stimulator, and the outer conductor is connected to the ground of the electrical stimulator. The inner conductor at the other end of the first coaxial cable is connected to the signal line of the NMR-compatible kit, and the outer conductor is connected to the ground of the NMR-compatible kit.

[0011] The MRI-compatible kit includes a first filter and a second filter; the first filter is installed in the operating room, the second filter is installed in the MRI scanning room, and the first filter is connected to the second filter via a fourth coaxial cable.

[0012] The first filter is fixed inside the first shielding box; the second filter is fixed inside the second shielding box.

[0013] The shielding box is a non-magnetic aluminum shielding box.

[0014] Both the first filter and the second filter are second-order passive RC filters.

[0015] This invention relates to a transcranial electrical stimulation (tDCS) system based on a magnetic resonance imaging (MRI) environment. It allows for MRI scans of subjects during and after tDCS stimulation to analyze the effects of stimulation on the brain. Functional magnetic resonance imaging (fMRI) technology offers high spatial resolution, enabling observation of the effects of tDCS on the brain both during and after stimulation, thus allowing for more accurate study of the mechanisms of action of tDCS. This has significant implications for understanding the fundamental mechanisms of tDCS, is simple to operate, and also offers the following advantages:

[0016] (1) The transcranial electrical stimulation system of the present invention can be used in a magnetic resonance environment;

[0017] (2) The shielding box used in the nuclear magnetic compatibility kit of the present invention is made of aluminum. Aluminum is not a magnetic material (i.e., a magnetic material), and can be used in 3.0T nuclear magnetic resonance with good shielding effect;

[0018] (3) The electrical stimulator part of the present invention can be selected from two modes: transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS).

[0019] (4) This invention makes it more convenient and accurate to study the mechanism of tDCS during and after stimulation. Attached Figure Description

[0020] Figure 1 This is a system structure diagram of the present invention;

[0021] Figure 2 This is a schematic diagram of the lithium battery charging circuit of the present invention;

[0022] Figure 3 This is the schematic diagram of the 3.7V to 5V circuit of the present invention;

[0023] Figure 4 This is the schematic diagram of the 5V to 3V3 converter circuit of the present invention;

[0024] Figure 5 This is the schematic diagram of the 5V to 24V circuit of the present invention;

[0025] Figure 6 This is the schematic diagram of the 5V to LCD 3V3 circuit of the present invention;

[0026] Figure 7 This is a schematic diagram of the microprocessor control circuit of the present invention;

[0027] Figure 8 This is a schematic diagram of the LCD driving circuit of the present invention;

[0028] Figure 9This is a schematic diagram of the LCD configuration section of the present invention;

[0029] Figure 10 This is a schematic diagram of the voltage buffer circuit of the present invention;

[0030] Figure 11 This is a schematic diagram of the differential proportional operation circuit of the present invention;

[0031] Figure 12 This is the principle of the current output circuit of the present invention;

[0032] Figure 13 This is an internal block diagram of the NMR compatibility kit of the present invention. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0034] like Figure 1 As shown, this invention is a transcranial electrical stimulation system suitable for use in a magnetic resonance imaging (MRI) environment, comprising an electrical stimulator, an MRI-compatible kit, and a fluorescence thermometer module. The electrical stimulator is a current source output and is connected to the MRI-compatible kit via a first coaxial cable. The MRI-compatible kit is connected to the electrical stimulation electrodes via a second coaxial cable and a third coaxial cable.

[0035] The electrical stimulator module includes a current source module, a microprocessor control module, an LCD control module, and the current source module itself. The current source module includes a lithium battery charging module and a voltage conversion module, wherein the voltage conversion module includes a 3.7V to 5V module, a 5V to 3V3 module, a 5V to 24V module, and a 5V to LCD 3V3 module (for powering the LCD screen), such as... Figures 2-6 As shown. Considering the portability of the electrical stimulator and the battery life, the embodiments of the present invention use a rechargeable lithium battery with a large capacity of 2000mAh and 3.7V polymer lithium battery, which has a protection board to prevent overcharge / over-discharge / short circuit / overcurrent.

[0036] like Figure 2As shown, the lithium battery charging module consists of a lithium battery B1, a chip U8, a USB-mini interface, inductors L2 and L3, a tantalum capacitor C33, resistors R34 and R37, and an LED D4. The lithium battery B1 is a 3.7V polymer lithium battery. The chip U8 is a TP4054. The charging interface is Mini-USB. Inductors L2 and L3 are both 10uH, tantalum capacitor C33 is 10uF, resistors R34 and R37 are both 1KΩ, and LED D4 is a red LED. The TP4054 chip is a complete single-cell lithium-ion battery constant current / constant voltage linear charger with a charging current of up to 500mA. The chip U8 is connected to the positive terminal of the lithium battery B1 via pin BAT, and the chip U8 is connected to the positive terminal of the lithium battery B1 via pin PRO. Connect one end of resistor R34 to pin G. Chip U8 is connected to ground PGND via pin GND, the other end of resistor R34, and the negative terminal of lithium battery B1. Chip U8 is connected to the negative terminal of LED D4 via pin CHRG. The positive terminal of LED D4 is connected to one end of resistor R37, and the other end of resistor R37 is connected to pin VIN of chip U8. Chip U8 is connected to the positive terminal of tantalum capacitor C33 via pin VIN. The negative terminal of tantalum capacitor C33 is connected to PGND. The positive terminal of tantalum capacitor C33 is connected to one end of inductor L2, and the other end of inductor L2 is connected to the VBUS pin of USB-mini. The negative terminal of tantalum capacitor C33 is connected to one end of inductor L3, and the other end of inductor L3 is connected to the GND pin of USB-mini. During lithium battery charging, indicator light D4 is constantly red.

[0037] like Figure 3As shown, the 3.7V to 5V module consists of chip U7, resistors R33, R35-R36, capacitors C32, C35, and C37, inductor L4, and Schottky diode D3. Chip U7 is model SX1308. Resistors R33 have a resistance of 1KΩ, R35 has a resistance of 73.2KΩ, R36 has a resistance of 10KΩ, capacitors C32 and C37 each have a capacitance of 4.7uF, capacitor C35 has a capacitance of 15pF, and Schottky diode D3 is model IN5819. Chip U7 connects the positive terminal of Schottky diode D3 to one end of inductor L4 via pin SW. The negative terminal is connected to one end of resistor R35; the other end of resistor R35 is connected to one end of resistor R36 and the FB pin of chip U7; capacitor C35 is connected in parallel with both ends of resistor R35; one end of capacitor C35 is connected to one end of capacitor C37, i.e., the +5V output of the 3.7V to 5V module; the other end of inductor L4, together with the IN pin of chip U7, one end of capacitor C32, and one end of resistor R33, is connected to the positive terminal VBAT+ of the lithium battery; the other end of resistor R33 is connected to the EN pin of chip U7; the other ends of capacitor C32, resistor R36, capacitor C37, and the GND pin of chip U7 are connected together to ground PGND.

[0038] like Figure 4 As shown, the 5V to 3V3 converter module consists of chip U10, resistor R39, resistors R43-R44, resistor R48, capacitors C38-C39, and capacitors C43-C44. Chip U10 is an ADP151. Resistor R39 has a resistance of 1KΩ. Resistors R43, R44, and R48 all have a resistance of 0Ω. Capacitors C39 and C44 each have a capacitance of 0.1uF, and capacitors C38 and C43 each have a capacitance of 4.7uF. Chip U10 is connected to capacitors C43 and C44, and one end of resistor R43 via pin VOUT. The other end of resistor R43 is... The module outputs +3V3. Chip U10 is connected to capacitors C38 and C39 via pin VIN. One end of resistor R39 is connected in parallel to the +5V output from the 3.7V to 5V conversion section. The other end of resistor R39 is connected to the EN pin of chip U10. The other ends of capacitors C38, C39, C43, and C44 are connected to the GND pin of chip U10 and then to ground PGND. One end of resistor R44 is connected to ground PGND, and the other end is connected to ground DGND. One end of resistor R48 is connected to ground DGND, and the other end is connected to ground AGND. The +3V3 output from this module is used by the microprocessor.

[0039] like Figure 5As shown, the 5V to 24V module consists of chip U9, capacitors C34, C36, C40-C41, and inductors L5-L7. Chip U9 is model WRA0524S-3WR2. Capacitors C34, C40, and C41 are all 10uF, capacitor C36 is 1uF, and inductors L5-L7 are all 4.7uH. Chip U9 is connected to one end of capacitor C36 and inductor L5 via pin Vin. The other end of inductor L5 and one end of capacitor C34 are connected to the +5V output of the 3.7V to 5V conversion section. The GND pin of chip U9, along with the other ends of capacitors C36 and C34, is connected to ground PGND. The -Vo pin of chip U9 is connected to one end of inductor L6, the other end of which is the output voltage -24V, and is connected to the negative terminal of tantalum capacitor C40. The positive terminal of tantalum capacitor C40 and the 0V pin of chip U9 are connected to ground AGND. The +Vo pin of chip U9 is connected to one end of inductor L7, the other end of which is the output voltage +24V, and is connected to the positive terminal of tantalum capacitor C41. The negative terminal of tantalum capacitor C41 is connected to ground AGND.

[0040] like Figure 6 As shown, the 5V to LCD 3V3 (LCD power supply) module consists of chip U12, resistor R47, resistors R50-R51, and capacitors C45-C47. Chip U12 is an ADP151, resistor R47 has a resistance of 1KΩ, resistors R50 and R51 both have a resistance of 0Ω, capacitors C45 and C47 both have a capacitance of 0.1uF, and capacitor C46 has a capacitance of 4.7uF. Chip U12 connects to capacitors C46 and C47 via pin VOUT, and resistors R50 and R51... One end of resistor R50 is connected to the LCD3V3 output; the other end of resistor R50 is connected to the LCD3V3 output; the chip U12 is connected to capacitor C45 through the VIN pin, one end of resistor R47 is connected to the +5V output of the 3.7V to 5V section; the other end of resistor R47 is connected to the EN pin of chip U12; the other ends of capacitors C45, C46, ​​and C47 are connected to ground PGND together with the GND pin of chip U12; one end of resistor R51 is connected to ground PGND, and the other end is connected to ground DGND.

[0041] The above Figures 2-6 The current source module provides power to the microprocessor control module, LCD control module, and current source module of the electrical stimulator.

[0042] The microprocessor control circuit module is the core of the entire system. The microprocessor's main functions are controlling the current output of the current source module and controlling the operation and display of the LCD control module. The microprocessor control module includes a microprocessor configuration module and an LCD control configuration module.

[0043] like Figure 7 As shown, the microprocessor configuration module consists of a power supply circuit, a clock circuit, a reset circuit, and an SWD debugging circuit. The microprocessor chip U6 is an STM32F103ZET6, which is one of the STM32F1 series developed by STMicroelectronics. It has a 32-bit core size, a speed of 72MHz, a program memory capacity of 256KB, a program memory type of FLASH, and a RAM capacity of 48K.

[0044] The power supply circuit of the microprocessor U6 consists of capacitor C27, capacitor C29, and resistor R30. The capacitance of capacitor C27 is 0.1uF, the capacitance of capacitor C29 is 10uF, and the resistance of resistor R30 is 10Ω. The +3V3 voltage output from the 5V to 3V3 current source module of the electrical stimulator is connected to the VDDA pin of the microprocessor U6 through resistor R30. The VSSA pin of U6 is connected to ground DGND. One end of capacitors C27 and C29 is connected to +3V3, and the other end is connected to ground DGND.

[0045] The clock circuit of the microprocessor consists of crystal oscillator Y1, capacitors C30-C31, and resistor R32. Crystal oscillator Y1 has a frequency of 8MHz, capacitors C30 and C31 each have a capacitance of 22pF, and resistor R32 has a resistance of 1MΩ. One end of crystal oscillator Y1 is connected to the OSC_IN pin of chip U6, and the other end is connected to the OSC_OUT pin of chip U6. Resistor R32 is connected in parallel with crystal oscillator Y1. One end of capacitor C30 is connected to one end of resistor R32, and the other end is grounded (DGND). One end of capacitor C31 is connected to the other end of resistor R32, and the other end is grounded (DGND).

[0046] The microprocessor's reset circuit consists of capacitor C14, resistor R27, and reset switch S1. The capacitance of capacitor C14 is 0.1uF, the resistance of resistor R27 is 4.7KΩ, and the reset switch S1 is a push-button switch. The microprocessor U6 is connected to one end of capacitor C14 and resistor R27 via pin NRST. The other end of resistor R27 is connected to +3V3 voltage, and the other end of capacitor C14 is connected to ground DGND. The reset switch S1 is connected in parallel across capacitor C14.

[0047] The SWD debugging circuit of the microprocessor consists of resistors R25 to R26 and a 4-pin header P2. The SWD interface is header P2, and the resistance values ​​of resistors R25 and R26 are both 4.7KΩ. The PA13 pin of the microprocessor U6 is connected to SWDIO, which is the 3rd pin of header P2. The PA14 pin of the microprocessor U6 is connected to SWCLK, which is the 2nd pin of header P2. The 1st pin of header P2 is grounded to DGND. The 4th pin of header P2 is connected to +3V3. Resistor R25 is connected between pins 3 and 4 of header P2. Resistor R26 is connected between pins 1 and 2 of header P2.

[0048] PA10 and PA9 of the microprocessor U6 are for serial port 1 transmission and reception, namely USART1_RX and USART1_TX. Similarly, through the four-pin header P1, PA9 is connected to pin 2 of P1; PA10 is connected to pin 3 of P1; pin 1 of P1 is connected to +3V3, and pin 4 is connected to ground DGND.

[0049] The microprocessor's mode selection pins BOOT0 and BOOT1 are connected in series with resistors R23 and R24 to ground (DGND), respectively. The resistance of both resistors R23 and R24 is 10KΩ. The microprocessor U6 is connected to one end of resistor R31 via pin PE5. The other end of resistor R31 is connected to the positive terminal of LED D2. The resistance of resistor R31 is 1KΩ. The negative terminal of LED D2 is grounded (DGND). The microprocessor U6 is connected to the LCD_RST pin of the LCD via pin NRST. The microprocessor U6 is connected to the LCD_CS pin of the LCD via pin FSMC_NE4. The microprocessor U6 is connected to the LCD_RS pin of the LCD via pin FSMC_A10. Microprocessor U6 is connected to the LCD_WR pin of the LCD via the FSMC_NWE pin; microprocessor U6 is connected to the LCD_RD pin of the LCD via the FSMC_NOE pin; microprocessor U6 is connected to the LCD_D0 pin of the LCD via the FSMC_D0 pin; microprocessor U6 is connected to the LCD_D1 pin of the LCD via the FSMC_D1 pin; microprocessor U6 is connected to the LCD_D2 pin of the LCD via the FSMC_D2 pin; microprocessor U6 is connected to the LCD_D3 pin of the LCD via the FSMC_D3 pin; microprocessor U6 is connected to the LCD_D4 pin of the LCD via the FSMC_D4 pin; microprocessor U6... The microprocessor U6 is connected to the LCD_D5 pin of the LCD via pin FSMC_D5; the microprocessor U6 is connected to the LCD_D6 pin of the LCD via pin FSMC_D6; the microprocessor U6 is connected to the LCD_D7 pin of the LCD via pin FSMC_D7; the microprocessor U6 is connected to the LCD_D8 pin of the LCD via pin FSMC_D8; the microprocessor U6 is connected to the LCD_D9 pin of the LCD via pin FSMC_D9; the microprocessor U6 is connected to the LCD_D10 pin of the LCD via pin FSMC_D10; the microprocessor U6 is connected to the LCD_D11 pin of the LCD via pin FSMC_D11; the microprocessor U6 is connected to the LCD_D11 pin of the LCD via pin FSMC_D11; the microprocessor U6 is connected to the LCD_D5 pin of the LCD via pin FSMC_D5; the microprocessor U6 is connected to the LCD_D6 ...7 pin of the LCD via pin FSMC_D8; the microprocessor U6 is connected to the LCD_D The microprocessor U6 is connected to the LCD_D12 pin of the LCD via the FSMC_D12 pin; the microprocessor U6 is connected to the LCD_D13 pin of the LCD via the FSMC_D13 pin; the microprocessor U6 is connected to the LCD_D14 pin of the LCD via the FSMC_D14 pin; the microprocessor U6 is connected to the LCD_D15 pin of the LCD via the FSMC_D15 pin; the microprocessor U6 is connected to the BL_CTR pin of the LCD via the PB0 (LCD_BL) pin; the microprocessor U6 is connected to the T_CLK pin of the LCD via the PB1 (T_SCK) pin; and the microprocessor U6 is connected to the T_CS pin of the LCD via the PF11 (T_CS) pin.The microprocessor U6 is connected to the T_MOSI pin of the LCD via pin PF9 (T_MOSI); the microprocessor U6 is connected to the T_PEN pin of the LCD via pin PF10 (T_PEN).

[0050] The LCD control configuration module includes an LCD driving circuit and an LCD configuration circuit, such as... Figures 8-9 As shown.

[0051] like Figure 8 As shown, the LCD driving circuit consists of chip U4, resistors R19-R22, capacitors C11-C12, tantalum capacitor C9, inductor L1, and Schottky diode D1. Chip U4 is an MP3302DJ; resistors R19 and R22 are both 10Ω; resistor R20 is 10KΩ; resistor R21 is 100KΩ; capacitors C11 and C12 are both 0.1uF; tantalum capacitor C9 is 10uF; inductor L1 has an inductance of 4.7uH; and Schottky diode D1 is an MBR0520. The +5V voltage output from the 3.7V to 5V module in the current source module is connected in series with resistor R19 to the chip. Chip U4 has pin IN; chip U4 is connected in series with capacitor C11 to ground DGND via pin IN; the positive terminal of tantalum capacitor C9 is connected to +5V, and the negative terminal is connected to ground DGND; chip U4 is connected to resistors R20 and R21 to ground DGND via pin EN; chip U4 is connected to resistor R22 to ground DGND via pin FB; chip U4 is connected to ground DGND via pin GND; chip U4 is connected to one end of inductor L1 via pin SW, and the other end of inductor L1 is connected to +5V; chip U4 is connected to one end of Schottky diode D1 via pin SW, and the other end of D1 is connected to one end of capacitor C12, and the other end of capacitor C12 is connected to ground DGND.

[0052] like Figure 9As shown, the LCD configuration circuit consists of a thin-film transistor (TFT1), a thin-film flexible interface (J2), resistors R17-R18, tantalum capacitors C7, C8, and C10. Resistors R17 and R18 are both 4.7KΩ, tantalum capacitor C7 has a capacitance of 10uF, and capacitors C8 and C10 are both 0.1uF. The LCD section of the microprocessor control unit is actually connected to the TFT1, specifically LCD_RST, LCD_CS, LCD_RS, LCD_WR, LCD_RD, and LCD_D0-LCD_D15 are connected to the RST, CS, RS, WR, RD, and DB0-DB15 pins of TFT1, respectively. The TFT1 is connected to LCD3V3 via pins VDD and IOVCC. The TFT1 is connected to ground DGND via pin GND. Capacitor C10 is connected in parallel between power supply LCD3V3 and ground DGND. The LED_A pin of the TFT1 is connected to the LCD driver. One end of capacitor C12 in the circuit is connected to Schottky diode D1; the LED_K pin of thin-film transistor TFT1 is connected to the FB pin of chip U4 in the LCD driver circuit; the thin-film flexible interface J2 is connected to LCD3V3 via the VDD pin, i.e., the output of the 5V to LCD3V3 section; J2 is connected to ground DGND via the GND pin; J2 is connected to T_CS of the microprocessor control module via the RST pin; J2 is connected to T_PEN of the microprocessor control module via the INT pin; J2 is connected to T_CLK of the microprocessor control module via the SCL pin; J2 is connected to T_MOSI of the microprocessor control section via the SDA pin; J2 is connected to one end of resistor R18 via the SCL pin, the other end of resistor R18 is connected to one end of capacitor C8, and the other end of capacitor C8 is connected to ground DGND; J2 is connected to one end of resistor R17 via the SDA pin, the other end of resistor R17 is connected to the positive terminal of tantalum capacitor C7, and the negative terminal of tantalum capacitor C7 is connected to ground DGND.

[0053] The current source module includes a voltage buffer circuit, a differential proportional calculation circuit, and a current output circuit, such as... Figures 10-12 As shown.

[0054] like Figure 10As shown, the voltage buffer circuit consists of chip U5, resistors R28-R29, capacitors C13, and capacitors C15-C16. Chip U5 is model AD8656, a dual operational precision CMOS amplifier, which is divided into U5A and U5B in the schematic diagram. Resistors R28 and R29 have a resistance of 4.7KΩ, and capacitors C13, C15, and C16 each have a capacitance of 0.1uF. The microprocessor U6 in the microprocessor control circuit outputs two DACs: DAC1 is output from pin PA4 of chip U6, and DAC2 is output from pin PA5 of chip U6. DAC1 passes through resistor R... DAC2 is connected to input pin 3 of chip U5, and input pin 3 of chip U5 is connected to ground DGND via capacitor C15; input pin 2 of chip U5 is connected to output pin 1; pin 4 of chip U5 is grounded to DGND; pin 8 of chip U5 is connected to +3V3 of the 5V to 3V3 current source module; one end of capacitor C13 is connected to +3V3, and the other end is grounded to DGND; DAC2 is connected to input pin 5 of chip U5 via resistor R29, and input pin 5 of chip U5 is connected to ground DGND via capacitor C16; input pin 6 of chip U5 is connected to output pin 7.

[0055] like Figure 11 As shown, the differential proportional operational amplifier circuit consists of chip U1, resistors R1-R4, and resistors Rf1-Rf2. Chip U1 is an ADA4522-2 dual operational amplifier, which is divided into U1A and U1B in the schematic diagram. Resistors R1-R4 are all 5KΩ, and resistors Rf1-Rf2 are also 5KΩ. Pin 8 of chip U1 is connected to the +24V output of the 5V-to-24V converter, and pin 4 of chip U1 is connected to the -24V output of the 5V-to-24V converter. In the voltage buffer circuit, pin 1 of chip U5 outputs DAC1, which is connected to one end of resistor R3, and the other end of resistor R3 is connected to chip U1. The circuit consists of several pins: pin 5 (the input pin of the chip); pin 6 (the input pin of the chip U1) is connected to one end of resistor R4, and the other end of resistor R4 is connected to pin 1 (the output pin of the chip U1); pin 7 (the output pin of the chip U5) in the voltage buffer circuit (DAC2) is connected to one end of resistor R1, and the other end of resistor R1 is connected to pin 3 (the input pin of the chip U1); one end of resistor R2 is grounded (AGND), and the other end is connected to one end of resistor Rf1 and pin 2 (the input pin of the chip U1), and the other end of resistor Rf1 is connected to pin 1 (the output pin of the chip U1); one end of resistor Rf2 is connected to pin 6 (the input pin of the chip U1), and the other end is connected to pin 7 (the output pin of the chip U1). This part of the circuit is actually a subtraction circuit. Because the selection and adjustment of resistors in a single operational amplifier circuit are inconvenient, and the input resistance is too small for each signal source, a separate circuit was designed. Figure 11 The differential proportional operational circuit with high input resistance is shown.

[0056] like Figure 12 As shown, the current output circuit consists of chip U2, resistors R6-R9, and resistor R12. Chip U2 is model ADA4522-2, a dual operational amplifier, which is divided into U2A and U2B in the schematic. Resistors R6-R9 are all 5KΩ, and resistor R12 is 300Ω. Pin 8 of chip U2 is connected to the +24V output of the 5V-to-24V converter in the current source module, and pin 4 of chip U2 is connected to the -24V output of the 5V-to-24V converter in the current source module. In the differential proportional operational circuit, pin 7 of chip U1 is connected to one end of resistor R7, and the other end of resistor R7... The resistor R8 is connected to pin 3 of chip U2; one end of resistor R8 is connected to pin 3 of chip U2, and the other end of resistor R8 is connected to pin 7 of chip U2; one end of resistor R6 is grounded to AGND, and the other end of resistor R6 is connected to pin 2 of chip U2; one end of resistor R9 is connected to pin 2 of chip U2, and the other end is connected to pin 1 of chip U2; one end of resistor R12 is connected to pin 1 of chip U2, and the other end is connected to pin 5 of chip U2, which is the output of the entire current source; pin 7 of chip U2 is connected to pin 6 of input.

[0057] The key circuitry in this section utilizes the enhanced Howland current source principle.

[0058] like Figure 12 As shown, when resistor R9 is large enough, the output current will remain constant. A larger R9 will reduce circuit speed and accuracy, but this problem can be solved by inserting a buffer in the feedback circuit to form an enhanced Howland current source. Assume the current output is connected to the load R... L That is, load R L One end of the resistor R12 is connected to terminal B, and the other end is grounded (AGND). All current flowing through resistor R12 flows into the load, and the current flowing through the load is denoted as i. L The output current will be calculated using formula (1):

[0059]

[0060] If R6 / (R9)=(R7) / R8=k (k is any positive integer), then the above formula can be simplified to formula (2). It can be seen that the output current is independent of the load and is only controlled by the input voltage.

[0061]

[0062] like Figure 13 As shown, the first coaxial cable consists of four layers: an inner conductor 14, an insulator 13, an outer conductor 12, and a sheath 11. One end of the first coaxial cable 1 is connected to the electrostimulator, where the inner conductor 14 is connected to the anode of the electrostimulator, i.e., the current output (terminal B of resistor R12), and the outer conductor 12 is connected to the ground AGND of the electrostimulator. The other end of the first coaxial cable 1 is connected to the first filter in the first shielding box 5, where the inner conductor 14 is connected to the signal line of the first filter, and the outer conductor 12 is connected to the ground GND1 of the first filter. Both the first and second filters are second-order passive RC low-pass filters, and their cutoff frequencies are both 1 kHz. One end of the fourth coaxial cable 4 has its inner conductor connected to the signal line of the first filter and its outer conductor connected to the ground GND1 of the first filter; the other end of the fourth coaxial cable 4 has its inner conductor connected to the signal line of the second filter in the second shielding box 6 and its outer conductor connected to the ground GND2 of the second filter. One end of the second coaxial cable 2 has its inner conductor connected to the signal of the second filter, and its outer conductor connected to the ground GND2 of the second filter. The other end of the second coaxial cable 2 has its inner conductor connected to one end of the 5K current-limiting resistor 1, and the other end of the 5K current-limiting resistor 1 is connected to the anode stimulation electrode via a coaxial cable. One end of the third coaxial cable 3 has its inner conductor connected to the ground GND2 of the second filter, and its outer conductor connected to the ground GND2 of filter 2. The other end of the third coaxial cable 3 has its inner conductor connected to one end of the 5K current-limiting resistor 2, and the other end of the 5K current-limiting resistor 2 is connected to the cathode stimulation electrode via a coaxial cable. The first filter is placed in the first shielding box 5, which is made of aluminum cuboid. A circular hole is opened at the center of the diagonal on each of the left and right sides of the first shielding box 5. The outer conductors of the first coaxial cable 2 and the fourth coaxial cable 4 are in close contact with the circular holes of the shielding box. The second filter is placed in an aluminum cuboid second shielding box 6. A circular hole is located at the center of the left diagonal of the second shielding box 6, and two circular holes are located on either side of the center of the right diagonal of the second shielding box 6. The outer conductors of the fourth coaxial cable 4, the second coaxial cable 2, and the third coaxial cable 3 are all in close contact with the circular holes in the shielding box. The first filter, the first shielding box 5, and the first coaxial cable 1 are placed in the operating room, while the second filter, the second shielding box 6, the fourth coaxial cable 4, the second coaxial cable 2, the third coaxial cable 3, and the stimulation electrode are all located in the MRI scanning chamber. One end of the optical fiber of the fluorescence thermometer module is connected to a temperature probe located below the anode electrode of the electrical stimulation, and the other end of the optical fiber is connected to the fluorescence thermometer. The other end of the fluorescence thermometer is then connected to a PC via RS485 communication protocol, and the corresponding software on the PC displays the temperature parameters in real time. The MRI compatibility kit is particularly important for the simultaneous use of electrical stimulation and MRI. The shielding box used in this part is made of non-magnetic aluminum, which can be used in the MRI environment and has good shielding properties, ensuring the normal operation of the two low-pass filters, filter1 and filter2.

Claims

1. A transcranial electrical stimulation system capable of synchronous use in a magnetic resonance imaging environment, characterized in that, The device includes an electrical stimulator, a fluorescence thermometer, and an NMR-compatible kit. The electrical stimulator is connected to the NMR-compatible kit via a first coaxial cable. The NMR-compatible kit is connected to the stimulation electrodes in the NMR spectrometer via a second and a third coaxial cable. The fluorescence thermometer is connected to the stimulation electrodes in the NMR spectrometer via an optical fiber. The MRI-compatible kit includes a first filter and a second filter; the first filter is installed in the operating room, the second filter is installed in the MRI scanning room, and the first filter is connected to the second filter via a fourth coaxial cable. The electrical stimulator includes a current source module, a microprocessor control module, an LCD control module, and a current source module; the current source module is connected to the microprocessor control module, the LCD control module, and the current source module, and is used to provide operating voltage; the microprocessor control module is connected to the LCD control module and the current source module, and is used to control the current output of the current source module and control the operation and display of the LCD control module; the LCD control module is used to connect to an LCD screen; the current source module is used to connect to an NMR-compatible kit via a first coaxial cable. The current source module includes a voltage buffer module, a differential proportional calculation module, and a current output module; the input terminal of the voltage buffer module is connected to the microprocessor control module, and the output terminal is connected to the differential proportional calculation module; the output terminal of the differential proportional calculation module is connected to the current output module; the current output module is used to connect to the NMR-compatible kit via a first coaxial cable. The current output module is equipped with a buffer to form an enhanced Howland current source; The first filter is fixed inside the first shielding box; the second filter is fixed inside the second shielding box.

2. The transcranial electrical stimulation system capable of synchronous use in a magnetic resonance environment according to claim 1, characterized in that, The current source module includes a lithium battery charging module and a voltage conversion module. The lithium battery charging module is connected to a rechargeable lithium battery, and the voltage conversion module is used to convert the voltage of the rechargeable lithium battery into the power supply voltage of the microprocessor control module, the LCD control module, and the current source module.

3. A transcranial electrical stimulation system capable of synchronous use in a magnetic resonance environment according to claim 1, characterized in that, The first coaxial cable comprises four layers, from the inside out: an inner conductor, an insulator, an outer conductor, and a sheath. The inner conductor at one end of the first coaxial cable is connected to the current source module of the electrical stimulator, and the outer conductor is connected to the ground of the electrical stimulator; the inner conductor at the other end of the first coaxial cable is connected to the signal line of the NMR-compatible kit, and the outer conductor is connected to the ground of the NMR-compatible kit.

4. A transcranial electrical stimulation system capable of synchronous use in a magnetic resonance environment according to claim 1, characterized in that, Both the first filter and the second filter are second-order passive RC filters.

5. A transcranial electrical stimulation system capable of synchronous use in a magnetic resonance environment according to claim 1, characterized in that, The shielding box is a non-magnetic aluminum shielding box.

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