A wide-band power-efficient inductive wireless link for implantable microelectronic devices using multiple-carriers

This paper presents a novel inductive link for wireless transmission of power and data to biomedical implantable microelectronic devices using multiple carrier signals. Achieving higher data bandwidth without compromising the power efficiency is the driving force behind using multiple separate carriers. Two separate pairs of coils have been utilized for inductive power and forward data transmission, plus a pair of miniature antennas for back telemetry. One major challenge, however, is to minimize the interference among these carriers especially on the implantable side, where size and power are highly limited. Planar power coils with spiral shape are optimized in geometry to provide maximum coupling coefficient k. The data coils are designed rectangular in shape and wound across the power coils diameter to be oriented perpendicular to the power coil planes. The goal is to maximize data coils direct coupling, while minimize their cross-coupling with the power coils. The effects of coils geometry, orientation, relative distance, and misalignments on the coupling coefficients have been modeled and experimentally evaluated.