Optimization And Application Research On The Wireless Powering Techniques For Micro Devices In Gastrointestinal Tract Inspecting And Therapy

Power supply is the vital issue during the developing and perfecting ofthe micro devices in gastrointestinal tract inspecting and therapy. Thesolving of this power supply problem, would pave the way to the realizationof increasement of working hours, improvement of image frames and theresolution, active locomotion, biopsy and herbicide placement. Wirelesspower transmission is attracting more and more attentions as the practicablemeans to deal with this energy conservation problem. By this measure, ourresearch focuses on the optimization and application research on thewireless powering techniques for the WCE under the support of the NationalHigh Technology Development Program.Based on the detailed analysis of the physiological characteristics ofhuman gastrointestinal tract, the problem and the feasible solutions havebeen analyses during the realization of the wireless power transmissionmodule, which is based on the electromagnetic coupling. The power transmission efficiency and the corresponding constraint conditions werededuced under the loose coupling case, where was an optimization modelbuilt to describe the design of the whole wireless power transmissionmodule, and a feasible way had been proposed to solving this optimizationproblem.The demands from the micro devices in gastrointestinal tract to thewireless power transmission module mainly focused on two aspects: thestability of the power supply and the safety to the human body. The stabilitydemand contains the position stability, the orientation stability and thefrequency stability. While the safety contains the human tissue safety in themagnetic field and the temperature raise safety inner the human body. Therelationship between these system demands and the design of transmittingcoil and receiving set were analyzed, combining with the constraints leadingby the physiological characteristics of human gastrointestinal tract, theconstraint conditions of the optimization model were composed.Multilayer solenoids pair of transmitting coil was proposed and varioustransmitting coil were measured and estimated from the angles of thesolving of the problem of position stability, frequency stability and humantissue safety in magnetic field. Uniform magnetic field was adopted to dealwith the position problem. The distribution of the magnetic field was deduced and simulated, and they were verified by the magnetic fieldmeasurement bench, then the uniformity of magnetic field was proposed toestimate the solving of the problem of the position stability. A test benchwas built to measure the stability of the transmitting coil. The frequencystability was defined as an important index of the transmitting coil and afeasible way to evaluate was designed. Thus, the frequency stability wasmanifesting itself in the optimization of the transmitting coil. The humantissue safety in the magnetic field induced by the transmitting coil wasconsidered. Based on the based on a high resolution human electromagneticcalculation mode, the current density and Specific Absorption Rate (SAR) inthe human body were calculated by the electromagnetic simulation softwareCell Signaling Technology (CST). According to the results above, the safetyindexes of the magnetic field were turned to be the limitation of the drivencurrent on transmitting coil.Considering the constraints of the shape and size, the receiving set wasoptimized from the points of solving the problem of orientation stability andtemperature raise safety. The orientation stability of the receiving coil wasdefined and modeled. The validity of it was firstly deduced and simulated,and then it vas validated by the practical measurement. Based on this, theparallel connected type and the serial connected type were compared, andthe fit range of each type was achieved. The magnetic core was induced to improve the space utilization rate. The actual relative permeability ofmagnetic core with different shape was analyses and practical measured, andthe octagonal section cylinder was proved to be better than the square one.Moreover, the suitable size of receiving coil under the given space was gotby solving the equation, and the number of turns of each coil wasdetermined by the solving of equation of higher order, which was leading bythe space geometry relationship between the three coils. The temperatureraise problem was turned to a constraint of the strands of the receiving coil,and it provides a feasible way to solving this problem.To verify the validity of the optimization model above, intestine robotand video capsule endoscope were optimized applying this model. Optimaldesign which satisfied the safety demands and power demands was achieved.The wireless power transmission module were realized according to theresults, and integrated to the whole system. Finally, the validity wasvalidated by the experiments.