Design of a RF-to-DC Link for In-Body IR-WPT with a Capsule-Shaped Rotation-Insensitive Receiver

This paper proposes the design and experimental validations of a 6.78 MHz IR-WPT with one conformal transmitter (Tx) and a couple of receiver (Rx) coils, suitable for powering implantable devices. The Rx coils are arranged in such a way that quasi-constant dc-output voltage and conversion efficiency are obtained, regardless of the receiver rotation, with respect to the transmitter. A 3-D miniaturized receiver, consisting of two elliptical coils wrapped around a capsule and orthogonal to each other, is faced to a conformal transmitter designed to maximize the magnetic flux in the receiver region. In order to avoid dark areas for energy transfer, due to unknown capsule rotations, each Rx coil is connected to one rectifier and the dc output ports are series-connected.