A number of implantable biomedical devices have been developed, and wireless power transfer (WPT) systems are emerging as a way to provide power to these devices without requiring a hardwired connection. Most of the WPT has been based on conventional conductive materials, such as metals, which tend to be less biocompatible and stiff. Herein, we describe a development of an ionic wireless power transfer (IWPT) system using hydrogel receivers that are soft and biocompatible. Although the hydrogel receiver has a lower conductivity than metal (ρgel/ρmetal ∼ 10-7), a capacitive coupling between receiver and transmitter enables the IWPT to deliver 4 mA of current at its resonance frequency. The capacitive coupling through the dielectric and the electrolyte was analyzed including a parasitic effect, and the IWPT was applied to implantable devices to transfer power via the skin. The IWPT system was further developed to facilitate electrosynthesis. Generation of nicotinamide adenine dinucleotide phosphate, a reducing agent in metabolism, was demonstrated by IWPT to show its potential for electrosynthesis.
Keywords: capacitive power transfer; electrosynthesis; hydrogel; implantable device; ionic device; stretchable ionic conductor; wireless power transfer.