Hollow Receiving Coil and Single Turn Element Analysis on Power for Wireless Capsule Endoscopy

Abstract

Wireless capsule endoscopy (WCE) is more and more popular in noninvasive detection on gastrointestinal (GI) disease. But the power supply is still a bottleneck. Insufficient power reduces image resolution and frame rate of data transfer, thus, unreliable medical diagnosis. Wireless power transmission (WPT) technology enables power supply for WCE. A hollow receiving coil (RC) with novel structure is proposed to minimize the capsule scale and solve the power issue. Single turn element analysis (STEA) is adopted to directly evaluate receiving power. Receiving power varies greatly when WCE is in different position and orientation of GI tract during the detection process. In some particular misalignment, power drops too low or jumps frequently. Then, optimization design of RC aimed at sufficient and stable power supply is implemented. The STEA is validated on test bench. The error of electromagnetic force is 0.2 V. The least receiving power with the optimal RC is 438.1 mW even in the worst misalignment. In the great majority of position and orientation misalignments, the optimal RC receives power over 650 mW. With the advantage of both computational time and accuracy, STEA is applicable for measurement and analysis on power for biomedical devices utilizing WPT technology, not merely WCE. In vivo experiment in pig's GI is accomplished with the optimal RC. The size of WCE with the novel RC gets smaller. And image stream is clear and fluent, when WCE is in any possible position and orientation of the tract. Four frames are stochastically sampled, in entropy of 7.1148, 7.3070, 7.2041, and 7.2570. Sufficient and stable power supply with the hollow RC enables advanced functions like drug release to come into being in WCE.