Objective Robotic capsule has gained immense attention of medical scientists and researchers in recent years, and the technology about robotic capsule has gained great improvements. However, affected by the limitation of size and biosecurity issues, power supply by Li battery or wire is deficient and effectively providing power has become a bottleneck which severely affects its development. Wireless power transmission based on inductive coupling is considered as a practical way to make a breakthrough in this field. Methods In this paper, a wireless power supply system for robotic capsule is presented, which could provide sufficient power at any orientation of the receiving coil. First, a transmitting coil consisted of two solenoid coils is presented, the structure of which is in accordance with the Helmholtz coil. Also, a three-dimensional orthogonal receiving coil with novel wire-wrapping and magnetic core is proposed. To check the effectiveness of the receiving coil, transmission efficiency of the wireless power transmission system from 0 to 360°is analyzed. Results Actual experiments are conducted on the platform consisted of the transmitting coil and in vitro transmitting circuit to find that the minimum transmission efficiency is 4.95% at any orientation between receiving coil and magnetic field, thus solve the problem of the inadequate power supply caused by the orientation change of the robotic capsule. Conclusions The system could provide more than 544mW power with 10.88W power input, which confirms the feasibility of the wireless power transmission system.
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