Multi-node coordinated regulation passive micro-magnetic stimulation system with distributed structure

Abstract

The invention discloses a multi-node coordinated regulation passive micro-magnetic stimulation system of a distributed structure, and belongs to the field of biomedical engineering. Firstly, a multi-node coordinated control passive micro magnetic stimulator of a distributed structure is designed, and the passive micro magnetic stimulator is composed of a transmitting coil, an identification coil, a micro coil (a stimulating coil and addressing coil assembly unit), a rectifying circuit and a crystal oscillator; secondly, based on the structure and characteristics of the micro-coil, designing a rectifying circuit for supplying power to a crystal oscillator so as to excite the addressing coil; then, a signal acquisition and frequency analysis module is established and is used for performing acquisition and frequency analysis on a frequency response signal of the micro-coil; and finally, each node micro-coil is identified, so that the positioning of the micro-coils and the monitoring of the cooperative working state are realized, multi-node cooperative magnetic stimulation is carried out, the long-term enhancement effect of the brain hippocampus CA1 region is enhanced, and the system has the potential ability of improving learning and memory.

Description

Technical Field

[0001] The present invention belongs to the field of biomedical engineering technology, and specifically relates to a passive micro-magnetic stimulation system with distributed structure and multi-node coordinated control. Background Art

[0002] A passive micromagnetic stimulator based on a distributed structure consists of a transmitting coil and a collection of multiple independent microcoils. It uses the magnetoelectric effect to precisely control multiple micro-implanted magnetic field sources, providing safe and effective energy to implants in different locations, thereby achieving synchronous neural regulation. Some studies have found that multi-site synchronous spinal cord stimulation can restore patients' motor function by stimulating different segments of the spine, and multi-site synchronous cardiac pacing stimulation can regulate the contraction of different ventricles to treat heart failure. Therefore, as a new type of neuromagnetic regulation technology, multi-channel synchronous synergistic stimulation has gradually become a research hotspot in this field due to its high flexibility and precise spatial regulation characteristics.

[0003] Wireless stimulation deployment can have the ability to easily expand the number of stimulation channels. In 2020, Lyu et al. proposed an inductively powered leadless dual-site cardiac pacing system that can flexibly deploy stimulation locations without wires. However, the implant is powered by two separate transmitters through frequency division multiplexing technology. Therefore, the external excitation end faces a more complex circuit structure, which limits the number of implants that can be used. In 2023, Tian et al. proposed a three-coil passive micromagnetic stimulation system for the hippocampus, using a multi-frequency resonant compensation network and frequency division multiplexing technology to wirelessly synchronize implants without physical contact. However, driving the multi-frequency circuit system has higher requirements for the output power and frequency of the power device, posing a challenge to the performance of the device. In 2024, Saha et al. used a multi-resonator WPT link to provide a reliable, uniform, distance-insensitive and transcutaneous wireless power delivery solution for various implantable and wearable medical devices. The above research shows that a key advantage of wireless stimulation is the ability to achieve multi-channel synchronous stimulation more flexibly. However, existing multi-channel implantable stimulators do not have a communication backhaul function, and are unable to monitor the working status of each stimulation node and accurately address it, thus affecting the reliability and accuracy of the stimulation effect.

[0004] To address the above issues, in 2021, Yu et al. introduced a wireless link stimulation system using the magnetoelectric effect, including wireless power supply via a shared transmitter and addressable controllable stimulation implants. The implants integrate chips, magnetoelectric films, capacitors, and electrodes to achieve individual addressing of the physical identification number of each implant, providing good scalability. In 2019, Khalifa et al. designed an implantable neurostimulator with a single transmitting coil and multiple stimulation coils. They proposed a method of assigning a specific resonant capacitor to each wireless stimulation coil for individual addressing of the stimulation site. The transmitting coil can individually control up to 10 different stimulators within the transmission frequency range of 0.5 GHz to 3 GHz, but the GHz signal selected by this method increases dielectric loss in the tissue. In 2024, Karimi et al. proposed a multi-site power supply and control system for implant networks. The system uses inductive links with resonant frequencies of 13.56 MHz and 6.78 MHz to address each implant. In the aforementioned research, individual addressing of stimulators was achieved by adjusting the oscillation frequency of the stimulator's oscillator circuit. However, the stimulator's impedance matching circuit is highly complex, and deviations in resonant capacitance matching can affect the number of implants and system performance. Therefore, achieving individual identification of multi-node signals and monitoring the operating status of each node through frequency division multiplexing, without changing the stimulator's resonant frequency, is crucial for improving the accuracy and effectiveness of multi-channel synchronous stimulation.

[0005] Therefore, this paper develops a distributed multi-node collaboratively controlled passive micro-magnetic stimulation system, which can monitor and locate the collaborative working status of each stimulator and perform collaborative magnetic stimulation on the hippocampus, with the potential to improve learning and memory. Summary of the Invention

[0006] The purpose of this invention is to realize high-frequency collaborative magnetic stimulation, and at the same time accurately locate the positions of multiple points and monitor the working status of multiple points. A passive micro-magnetic stimulation system with distributed structure and multi-node collaborative control is designed.

[0007] The technical solution of the invention is:

[0008] A distributed multi-node coordinated passive micro-magnetic stimulation system, characterized by the design of the distributed multi-node coordinated passive micro-magnetic stimulation system, the identification of micro-coils, and the coordinated control of the passive micro-magnetic stimulation system. The specific contents are as follows:

[0009] (1) Design of a distributed multi-node coordinated passive micro-magnetic stimulation system

[0010] The passive micro-magnetic stimulation system with multi-node coordinated control of the distributed structure is designed. The specific structure is as follows: Figure 1As shown in the figure, it mainly consists of a transmission and recognition module, a micro coil, and a signal acquisition and frequency analysis module.

[0011] A. Transmission and identification module

[0012] The transmission and identification module consists of two parts: a transmitting coil and an identification coil. Both the transmitting and identification coils are constructed from Litz wire with excellent high-frequency characteristics. The transmitting coil is a circular coil with a radius of 1.25 cm, 21 turns, and a wire diameter of 0.5 mm. Its inductance is 11.1 μH, and its resonant capacitance is 92.9 pF at a resonant frequency of 4.9 MHz. The identification coil is a circular coil with a radius of 1.25 cm, 9 turns, and a wire diameter of 0.2 mm. Its inductance is 300 nH. To prevent cross-coupling of signals, the transmitting and identification coils are placed in a cross pattern.

[0013] B. Microcoil

[0014] The microcoil consists of four parts: a stimulation coil, a rectifier circuit, a crystal oscillator, and an addressing coil. The stimulation coil is a planar square spiral coil with 4 turns, a line thickness of 35 μm, a line width of 110 μm, a line spacing of 70 μm, a length × width of 2.5 mm × 2.5 mm, an inductance of 300 nH, and a resonant capacitance of 3.5 nF at a resonant frequency of 4.9 MHz. The rectifier circuit consists of two capacitors and two Schottky diodes. The capacitor type is RF0 402. The Schottky diode used is BAT63-02V, with an output voltage of up to 2.2V. The crystal oscillator uses the SX2MX.000E20F30TJN, with a power supply threshold of 0.8V, which the rectifier's output voltage meets. The addressing coil is a planar square spiral coil with 8 turns, a wire thickness of 35μm, a wire width of 110μm, a wire spacing of 70μm, a length × width of 3.6mm × 3.6mm, and an inductance of 1.7uH. This microcoil converts energy into a magnetic field for neural magnetic stimulation and converts the collected energy into direct current to power the crystal oscillator and excite the addressing coil.

[0015] C. Signal acquisition and frequency analysis module

[0016] The signal acquisition and frequency analysis module includes an AD9226 analog-to-digital converter and an FPGA. The ADC receives the frequency response signal from the identification coil, while the FPGA, using the EP4CE10F17I7N, analyzes the frequency response signal, enabling precise identification and positioning of the microcoil system's operating status and spatial position.

[0017] (2) Identification of microcoils

[0018] An excitation signal with a frequency of 4.9MHz and a current of 0.9A is passed into the transmitting coil, and then the micro coils are placed in sequence. The crystal oscillator frequencies corresponding to the three micro coils are 8MHz, 10MHz, and 12MHz, respectively, and the output voltages of the three crystal oscillators are 2.72V, 2.6V, and 2.56V, respectively. Figure 2 A microcoil system is placed in the CA3 region of the hippocampus of the brain, and Fourier analysis is performed on the output signal of the recognition coil. The results are as follows Figure 3 A, can identify the 12MHz signal, so it can be determined that the addressing frequency of the stimulation coil is 12MHz, so '12' is used as the identification number of the microcoil. Then select a microcoil and place it in the CA1 area of ​​the hippocampus and perform frequency identification. The results are as follows Figure 3 .B, the identification number of this microcoil is '8'. Finally, the third microcoil is placed in the DG region of the hippocampus. The results are as follows Figure 3 .C, the identification number is '10'. The identification number can be used to determine the operating status of each target microcoil and the number of valid working points. If one of the identification numbers cannot be detected, it indicates that the microcoil has a link failure and is not working properly, and needs to be replaced.

[0019] (3) Coordinated regulation of passive micromagnetic stimulation system

[0020] The main function of the distributed structure is the multi-point synergistic effect in space. Therefore, a single microcoil was selected for single-point magnetic stimulation of the CA1 area; two microcoils were selected for multi-point synergistic magnetic stimulation, acting on the CA1 and CA3 areas at the same time; compared with single-point magnetic stimulation, the two-point synergistic stimulation effect was better than single-point stimulation, and the long-term potentiation effect of synaptic plasticity in the CA1 area increased by 47%.

[0021] The advantages and positive effects of the present invention are:

[0022] This paper designs a distributed multi-node coordinated passive micromagnetic stimulation system. The microcoil's unique frequency response enables precise multi-point positioning and multi-point operating status monitoring, while also delivering 4.9MHz high-frequency magnetic stimulation. Measurements demonstrate that this system not only enables individual addressing, status monitoring, and multi-channel synchronous stimulation, but also demonstrates superior multi-point coordinated magnetic stimulation in enhancing long-term potentiation compared to single-point magnetic stimulation, potentially improving learning and memory. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural diagram of a distributed multi-node coordinated control passive micro-magnetic stimulation system.

[0024] Figure 2 This is the output signal diagram of 8MHz, 10MHz and 12MHz crystal oscillators.

[0025] Figure 3 This is the identification result diagram of the micro coil. DETAILED DESCRIPTION

[0026] The present invention is further described below with reference to the accompanying drawings and examples.

[0027] Implementation method one:

[0028] Step 1: Determine the structure, material and geometric parameters of the transmitting coil, stimulation coil and addressing coil;

[0029] Step 2: Design the rectifier circuit and select the crystal threshold voltage, size and frequency;

[0030] Step 3: Determine the structure, material and geometric parameters of the identification coil;

[0031] Step 4: Build the passive micromagnetic stimulation device according to steps 1, 2, and 3, and determine the number of bits of the analog-to-digital converter and the sampling frequency of the FPGA;

[0032] Step 5: Based on the fourth step, determine the feasibility of the multi-node coordinated passive micro-magnetic stimulation system, and realize the positioning of the micro-coils at each node and the monitoring of the coordinated working status;

[0033] Step 6: Carry out multi-node coordinated magnetic stimulation according to step 5 to enhance the long-term potentiation effect of the CA1 area of ​​the hippocampus of the brain.

Claims

1. A distributed multi-node coordinated passive micro-magnetic stimulation system, characterized by: No. Step 1: Design of a distributed multi-node coordinated passive micro-magnetic stimulation system It mainly consists of a transmission and recognition module, a microcoil, and a signal acquisition and frequency analysis module. The details are as follows: A. The transmission and identification module consists of two parts: a transmitting coil and an identification coil. The transmitting coil is a circular coil with a radius of 1.25 cm, 21 turns, a wire diameter of 0.5 mm, an inductance of 11.1 μH, and a resonant capacitance of 92.9 pF at a resonant frequency of 4.9 MHz. The identification coil is a circular coil with a radius of 1.25 cm, 9 turns, a wire diameter of 0.2 mm, and an inductance of 300 nH. To avoid cross-coupling of signals, the transmitting coil and the identification coil are placed in a cross shape. B. The microcoil consists of four parts: a stimulation coil, a rectifier circuit, a crystal oscillator, and an addressing coil. The stimulation coil is a planar square spiral coil with 4 turns, a line thickness of 35 μm, a line width of 110 μm, a line spacing of 70 μm, a length × width of 2.5 mm × 2.5 mm, an inductance of 300 nH, and a resonant capacitance of 3.5 nF at a resonant frequency of 4.9 MHz. The rectifier circuit consists of two capacitors and two Schottky diodes. The capacitor type is RF. 0402, the Schottky diode is BAT63-02V, and the output voltage can reach 2.2V; the crystal oscillator is SX2MX.000E20F30TJN, and the power supply threshold is 0.8V. The output voltage of the rectifier meets this power supply threshold condition. The addressing coil is a planar square spiral coil with 8 turns, a line thickness of 35μm, a line width of 110μm, a line spacing of 70μm, a length × width of 3.6mm × 3.6mm, and an inductance of 1.7uH. C. The signal acquisition and frequency analysis module includes an AD9226 analog-to-digital converter and an FPGA. The analog-to-digital converter is used to receive the frequency response signal of the identification coil; the FPGA uses the EP4CE10F17I7N to perform frequency analysis on the frequency response signal, thereby achieving accurate identification and positioning of the micro-coil system's working status and spatial position; Step 2: Identification of the Microcoil An excitation signal with a frequency of 4.9MHz and a current of 0.9A is passed through the transmitting coil, and the microcoils are placed in sequence. The crystal oscillator frequencies corresponding to the three microcoils are 8MHz, 10MHz, and 12MHz, respectively, and the output voltages of the three crystal oscillators are 2.72V, 2.6V, and 2.56V, respectively. First, a microcoil system is placed in the CA3 region of the hippocampus of the brain. Fourier analysis is performed on the output signal of the identification coil. A 12MHz signal can be identified, so it can be determined that the addressing frequency of the stimulation coil is 12MHz. Therefore, '12' is used as the identification number of the microcoil. Another microcoil is selected and placed in the CA1 region of the hippocampus of the brain and frequency identification is performed. The identification number of this microcoil is '8'. Finally, a third microcoil is selected and placed in the DG region of the hippocampus of the brain, with the identification number '10'. The identification number can be used to determine the working status of the microcoil at each target point and the number of valid working points. If one of the identification numbers cannot be detected, it means that the microcoil has a link failure problem and cannot work normally and needs to be replaced. Step 3: Coordinated Control of the Passive Micromagnetic Stimulation System A single microcoil was selected for single-point magnetic stimulation of the CA1 area; two microcoils were selected for multi-point coordinated magnetic stimulation, acting on the CA1 and CA3 areas at the same time. Compared with single-point magnetic stimulation, the effect of two-point coordinated stimulation was better than single-point stimulation, and the long-term potentiation effect of synaptic plasticity in the CA1 area increased by 47%.

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