Wireless power and data transmission for robotic capsule endoscopes

Capsular endoscopy is a promising alternative to traditional gastro-intestinal (GI) examination techniques launched in the late ´90s. Although this approach has the potential to significantly change the examination procedure, the performance of currently available capsules is still too poor to take over traditional techniques. A major constraint that hinder the breakthrough of these devices is the limited power amount that can be stored into a tiny pill. Most commercial capsules use two watch batteries that can only provide an average power of 25 mW for about 6 hours, certainly not sufficient for a high resolution video stream or advanced robotic features. An inductive powering system has been developed which was proven to safely support the wireless transfer of over 300 mW. The system relies on a set of orthogonal ferrite (3D) coils, embedded in the capsule, and an external unit based on a Helmholtz coil driven by a class E amplifier. Control data can be sent through the inductive link by modulating the power carrier, whereas a dedicated high data rate RF link is used to transfer the images from the capsule to the base station. Besides evaluating the compatibility with radio transmission, several demonstrators were assembled combining the wireless powering system with various capsule dedicated modules.