An inductive power link for a wireless endoscope

An inductive link is presented that can handle freedom of motion. The envisaged application is to power a wireless camera capsule used for non-invasive visual inspection of the small bowel. Up to 150 mW of usable dc power can be delivered to the capsule for the entire duration of its travel along the gastric track. The outer dimensions of the power receiver compartment inside the capsule are theta 10 mm. x 13 mm. The power efficiency of the link is measured to be 1% under worst-case geometrical conditions. The issue of patient's health and safety regarding exposure to the electromagnetic field is addressed. To this purpose, an experimental method is applied to predict specific absorption rates. Conversely, the effect of biological tissue on link performance and practical workability is evaluated as well. Electric shielding of the transmitter coil is applied to reduce biological tissue interaction. In this way, appliance on a living subject is made both safe and practically feasible. (c) 2006 Elsevier B.V. All rights reserved.