| This paper presents a magnetic resonance-powered implanted neurostimulator,which consists of two parts: magnetic resonance energy transmission system and implantable neurostimulator.Among them,the magnetic resonance energy transmission system wirelessly energizes implantable nerve stimulators,thereby avoiding the pain caused by frequent battery replacement to patients;the implantable neural stimulator adopts closed-loop feedback control to adjust the stimulation parameters in real time,thereby improving the nerve stimulation efficiency.This article focuses on the development of implantable neurostimulators from the following aspects:1.Analyze the current research status of implantable neural stimulators at home and abroad,summarize the technical problems that need to be solved urgently,and propose the design concept of magnetic resonance power supply implantable neural stimulator system.2.According to theoretical analysis,corresponding system solutions and technical indicators are given The principle and characteristics of magnetic resonance energy transmission system are analyzed in detail,and the system design scheme of coil structure,power amplification,resonance frequency and transmission efficiency is given;at the same time,according to the clinical design requirements of implantable nerve stimulators,system design schemes such as biphasic stimulation,low power consumption,miniaturization,and communication security are given.3.Based on the analysis of the system design scheme and circuit model,design the hardware module circuits in the magnetic resonance energy transmission system,and the simulation and optimization of each module circuit,including high-frequency oscillation circuit,emitter follower circuit,power amplifier circuit,resonant energy transmission and receiving circuit and rectifier filter network.Based on the above system circuit design,a magnetic resonance energy transmission module with adjustable frequency,power and energy conversion efficiency is proposed.4.The design of the key module circuit of the implantable neural stimulator system is emphatically introduced.The stimulation pulse generation circuit,the neural signal processing circuit,and the implementation of the energy storage and management circuit are mainly analyzed,a stimulus pulse generation circuit based on a mirror current source is proposed.Finally,the embedded software design idea of the implantable neural stimulator in closed-loop mode is expounded.5.According to the overall system design and the design of each module,the development of the system prototype was completed,and the wireless power supply test and animal experiment organized by the organism were performed on the system prototype.System test results show that the operating frequency of magnetic resonance energy transmission system is continuously adjustable from 1.62 MHz to 2.00 MHz,and its band coverage coefficient is 1.23.When the supply voltage is +12V,the operating frequency is 2MHz,the transmission distance is 20 mm,the biological tissue thickness is 10 mm,and the load resistance is 1.5K?,the transmission efficiency of the system can reach 8%.The stimulation pulse amplitude of the implantable neural stimulator can be adjusted in a wide range from 10 ?A to 30 mA.The pulse frequency can be adjusted from 1 to 300 Hz,and the pulse width can be adjusted from 100 ?s to 2500 ?s.The local field potential processing circuit has a gain of 40 dB in the range of 0-200 Hz,and the spike signal processing circuit has a gain of 80 dB in the range of 300 Hz-5 KHz.Finally,a surgical experiment of rat epilepsy was performed.Experiments showed that the implanted neural stimulator prototype has a remarkable curative effect on neurological diseases. |
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