Wireless powering for miniature implantable systems

Abstract

The miniaturization of electronics has paved way for implantable devices at the scale of a millimeter or less. Progress in energy storage technologies, however, has been slower and the miniaturization of the power source remains unsolved. Wireless powering provides a potential solution in which electromagnetic energy is transferred from an external source. In this chapter, we analyze powering in the weakly coupled regime and discuss a specific example for a cardiac implant. For a weakly coupled device, we show that optimal powering occurs in the mid-field where power transfer occurs though a combination of inductive and radiative modes in tissue, in contrast to conventional inductive coupling.