Analysis of SAR and Current Density in Human Tissue Surrounding an Energy Transmitting Coil for a Wireless Capsule Endoscope

This paper reports on a prototype energy transmission system for a wireless capsule endoscope and the electromagnetic effects that influence its use in biological tissues. Specific absorption rate (SAR) and current density were analyzed by an electromagnetic simulator in a model consisting of a primary coil and a human trunk that included eighteen different organs. SAR and current density as a function of frequency were analyzed. The SAR was maximized at muscle and fat, and was below the basic restrictions of the International Commission on Non Ionizing Radiation Protection (ICNIRP). At the same time, the results for current density were maximized at muscle and intestine, and were below the ICNIRP basic restrictions, indicating that it was possible to safely transmit energy up to 30 mW at the frequency of 300-600 kHz.