Transmitter Adaptation and Wireless Power Control for Capsule Endoscopy

Inductive coupling, a form of wireless power transfer (WPT) offers a promising solution for enabling wireless capsule endoscopes (WCEs) when direct wire connections are impractical. In this approach, a 1-D receiving coil is integrated into a WCE, which is positioned within the stomach. Simultaneously, a 3-D transmitting coil (3DTC) is constructed outside the human body to provide the necessary power for the operation of the WCE. The WPT system described in this article is the first complete prototype wherein the receiving coil is integrated within a fully functional WCE and capable of accommodating an adult human body with the 3DTC. Mathematical analysis and computer simulations have verified the magnetic field direction at the center of the 3DTC can be precisely controlled to any orientation by manipulating the 3DTC currents. The static measurements of the WCE-received power at various angles from 0 to 180° range between 1210 mW and 1822.5 mW, which are all above the power requirement of typical WCEs. In the subsequent adaptive test, the inertial measurement unit in the WCE collects the orientation information of the capsule and, then, wirelessly transmits it to the microcontroller unit of the 3DTC controlling the coils' excitation. It is confirmed that the proposed system is able to control the coil excitation following the capsule rotation as it would within the human stomach.