The Research Of Magnetic Acupoint Stimulation System And Evoked EEG Feature

Magnetic acupoint stimulation combines magnetic stimulation technology with traditional acupuncture theory and stimulates acupoint using induced current, which produced by magnetic coil and conducted through the meridian line to activate the excitable tissue cells connected with acupoint, in order to treat some diseases. Compared with traditional acupuncture and electrical stimulation, magnetic acupoint stimulation has many unique advantages, such as noninvasive cure, no uncomfortable sensation, easily repeating and deep stimulation.Because magnetic acupoint stimulation is a new magnetic stimulation technology in recent years, of which relevant mechanism and stimulation method are still in the experimental research stage, there are many key problems to be solved, such as:magnetic focus and optimization of the acupoint stimulation coil, effective stimulation methods, evoked EMG and EEG characteristics by electromagnetic stimulation, etc. According to the problems in magnetic acupoint stimulation technology at present, this paper focuses on the design of magnetic stimulator and evoked EEG feature extraction, researching the brain bioelectrical effects evoked by magnetic acupoint stimulation. Concrete works done are shown as follows:(1) Handware system design of magnetic stimulator. In order to obtain a accurate adjustable stimulus signal, this paper, based on DDS technology, using C8051F021MCU and the built-in analog/digital peripherals, designed magnetic stimulator hardware circuit, which produces adjustable frequency, intensity and waveform’s electromagnetic stimulation signal. Meanwhile, the circuit can realize external button control and display the stimulation signal parameters, etc.(2) Optimization design of magnetic coil. On the basis of theoretical analyzing the magnetic field distribution of current-carrying coil, this paper designed different structures of figure-of-eight and bowl-shaped coils and simulated the magnetic field distribution using Ansys software of finite element analysis, studying the magnetic focus and stimulative depth of figure-of-eight and bowl shaped coils. The optimal coil shape and parameters suitable for magnetic acupoint stimulation system were obtained which provides a good foundation for magnetic acupoint stimulation technology applying to clinical care.(3) Software system design of magnetic stimulator. In order to make the software portability and versatility, the magnetic stimulator software system was designed with C language modular programming. Meanwhile using the C8051F021MCU built-in timer timing, the magnetic stimulator produced high precision stimulation signal. And the additional external storage could store the stimulation signal parameters, in order to prevent loss of parameters after power interruption.(4) The feature research of evoked EEG signal by electromagnetic acupoint stimulation. Because of different electromagnetic stimulation modes evoking different EEG signal, this paper, using40-lead EEG event-related potentiometer to collect evoked EEG signal and power spectral analysis method to extract EEG characteristics, researched the evoked EEG signal influence of magnetic acupoint stimulation’s time effect, frequency effect, stimulus intensity and stimulus waveform. The results showed that: the most obvious EEG characteristics was evoked by the frequency of200Hz, the intensity of2mT and acupoint stimulaion within5-10minutes; after removing the stimulus for5minutes, the EEG characteristics returned to normal.In this paper, the design of the magnetic acupoint stimulator and stimulation methods lays a good foundation for electromagnetic stimulation technology applying in the treatment of nervous system diseases and motion system rehabilitation training.