Using magnetic resonance wireless power transfer to operate a scalpel on a prototype of a robotic therapeutic endoscope

摘要

Currently, capsule endoscopy (CE) is limited to diagnosis. However we have been trying to make a paradigm shift in capsule endoscopy (CE) by developing therapeutic capsule endoscopes. CE has always had the limitation of a short battery life. As conventional batteries do not have enough power (30W) to enable an electrical scalpel or a snare to resect lesions or coagulate bleeding vessels, we have been investigating the possibility of using wireless power transfer. Even though several studies have reported that it is possible to power a capsule endoscope wirelessly, the amounts of power transferred were very small (0.0008-0.05W) and are too low to operate a scalpel. In this study, we clarified that the magnetic resonance method of wireless power transfer could supply enough power to a bipolar scalpel for it to cut and coagulate a piece of porcine mucosa in a phantom filled with CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Bluetooth control signals from a smartphone were used to navigate a prototype of a robotic capsule endoscope and work the scalpel equipped on it. To get a high efficiency over 20 percent, the receiving coil was built into a foldable umbrella-shaped antenna, which kept the Q factor high, and the resonance frequency was monitored and adjusted automatically to keep it as close as possible to the optimum frequency (350 KHz). Transmitting at 350 kHz and operating the scalpel at the same frequency meant there was no DC conversion; which also improved total efficiency. At a distance of 10cm between the transmitter and receiver the circuit configuration could supply 20W of power to the tip of the scalpel, which was enough to work the scalpel in CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> .