| As the development of the bioengineering and micro electromechanical technology, as well as the demand of improvement in medical treatment, the mini-invasive and non-invasive medical microsystem inside human has been the key research of the bioengineering area and the electromechanical area. At the same time, as the key problem of the mini-invasive and non-invasive medical microsystem inside human, the energy problem has always been the restriction for its further development.Under the support of The National High Technology Research and Development Program of China (863 Program) (Program Number:2006AA04Z368 ) and National Natural Science Foundation of China(Program Number:30570485),this paper carried out the research of the wireless energy transmission system for these mini-invasive and non-invasive medical microsystem, developed a double closed-loop wireless energy transmission system based on electromagnetic induction principle. The system could provide energy for the microsystems from outside, and adjust the transmit efficiency according to the variation of the microsystem’s movement in order to keep the stability of the receive energy. The research contained following aspects:(1) The energy transmission efficiency and the max-efficiency condition of the Serial Resonant Structure and the Parallel Resonant Structure were analyzed. For the Serial Resonant Structure used in this paper, through the deeper analysis on the factors that affect the energy transmission efficiency, the conclusion that the efficiency would increase with the working frequency, mutual inductance and load resistance’s increase, and would decrease with the increase of the inner resistance of the transmit coil and receive coil was gained.(2) The mutual inductance model was set and experiment was done to analyze the relationship between the mutual inductance and the radius, distance displacement, angle displacement of the two coils, as the mutual inductance of the two coils was the main factor that affecting the energy transmission efficiency. (3) Through the comparison of the two kinds of transmit circuit: Class E Amplifier and Full Bridge Inverter, the paper chose the full bridge inverter as the transmit circuit, with the Phase Lock Loop applied in, an auto frequency tracking transmit circuit was designed, which could make the transmit coil always work in the resonant condition. The transmit power adjust method was discussed and the transmit power adjust circuit was designed with the adjustable switch power supply, providing the possibility of the feedback control.(4) The energy receive circuit in the microsystem was designed, the feedback control circuit was implemented through the wireless communication circuit. The PID control arithmetic was applied into the feedback control system, the parameters of PID control arithmetic were also selected through experiments.(5) Experiment showed that when receiving coil was placed at the center of the transmitting coil with the axial parallelism, the efficiency of the designed double closed-loop wireless energy transmission system could reach 1.31%, the application of the wireless energy transmission system in the microrobot for gastrointestinal detection and the micro capsule endoscope were also given and experimented.As the key problem of the mini-invasive and non-invasive medical microsystem, wireless energy transmission technology has attracted much attention, but the research can not be completed in few days, there are still many works to do for the real practicality. In the coming future, the research on this area will focus on the improvement of energy transmission efficiency, the three dimensions transmit or receive coil for solving the uncertainty of the receive coil problem. It can be believed that the mini-invasive and non-invasive medical microrobot and micro capsule with efficient wireless energy transmission power will be helpful for the clinic research in future. |
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