Study On Efficiency Of Wireless Energy Transmission In Site-specific Drug Delivery Micro-system In Alimentary Canal

The Site-special Drug Delivery Capsule Micro-system is one of the important branches of the diagnosis and treats system in alimentary canal. With the development of MEMS (Micro Electromechanical Systems) technology and the medicine, the diagnosis and treat system in alimentary canal is increasingly concerned by the public. However, energy supply becomes a bottleneck which holds back the development of capsule-style micro-system because of the high speed development of micro-electronic technology. Traditional battery-powered model which occupies large space and is harmful and has no real-time power replenishment limits its application. Wireless energy transmission which based on electromagnetic induction technology and modern electronic technology realizes safe, reliable and high efficiency contactless energy transfer from stationary source to micro-system via magnetic coupling.This paper intensively studied the transfer efficiency of wireless energy transmission in site-specific drug delivery micro-system in alimentary canal. The topologies structure of compensation circuits and various influence factors of wireless energy transmission were analyzed as well. Then, through the calculation of mutual inductance between emission coil and receive coil at random direction, the relationship between axial distance,lateral misalignment and pitch displacement of coil and the mutual inductance is found out, which can offer the theoretic evidence for the design of the coils.In this paper, the design of emission coil and receive coil for wireless energy transmission was presented. And the author elaborated the choice of transmission coils. The magnetic field in spiral plane circular coil,spiral plane square coil and Helmholtz coil were analyzed respectively and the figures of magnetic field distribution were simulated elaborately by using the computer-aided analysis. At the same time, the author elaborated impedance matching process and got the appropriate matching results and discussed the methods solving the energy coupling blind spot problems by using different coils. The reasons that the parameters of coils changed when human intervened were analyzed. Through comparative experiments of transmission coils, we used Helmholtz coil which had good, large magnetic field homogeneity and less influence by human intervention as emission coil .On the design of the receive coils, the author contrasted the merit and shortcoming of spiral plane coil on a chip and spiral coil, and chose the spiral coil as receive coil based on its simple structure and having better coupling efficiency ,and used double-layer winding way to improve the coupling energy capability.To verify the feasibility of wireless energy transmission system, we made many wireless energy transmission experiments taking advantages of the equipment we designed. A shielding box was used for suppressing electromagnetic interference and assuring that the experimental data was accurate. The result indicated that the equipment could effectively transmit milliwatt power to load wirelessly and had better energy transfer efficiency.