Wireless power transmission in endoscopy capsules

The operating life of endoscopy capsules is limited by the batteries needed for use. The capacity of corresponding batteries, however, is too short to cover the total period of gastrointestinal transit. To overcome this limitation, a novel kind of wireless power transmission was used. It utilizes a permanent magnetic cylinder located outside the patient's body and is turned by an electric motor, thereby generating a rotating magnetic field. This field in turn causes the motor, by a permanent magnetic sphere, located in a liquid bearing inside the endoscopy capsule, to rotate synchronously. The sphere induces an alternating voltage in coils inside the capsule and thus provides the necessary power. This arrangement was able to transmit power of up to 170 mW. This value is clearly higher than the minimum power of 100 mW needed to operate the electronics of the endoscopy capsules that are actually in use. The volume of both the sphere and the induction coil is smaller than the batteries that are actually integrated in the capsules. By this means, the operating time may be prolonged, in principle up to arbitrary values.