Stretchable Transparent Wireless Charging Coil Fabricated by Negative Transfer Printing

A wireless optoelectronic skin patch for light delivery and thermal monitoring

Wearable optoelectronic devices can interface with the skin for applications in continuous health monitoring and light-based therapy. Measurement of the thermal effect of light on skin is often critical to track physiological parameters and control light delivery. However, accurate measurement of light-induced thermal effects is challenging because conventional sensors cannot be placed on the skin without obstructing light delivery. Here, we report a wearable optoelectronic patch integrated with a transparent nanowire sensor that provides light delivery and thermal monitoring at the same location. We achieve fabrication of a transparent silver nanowire network with >92% optical transmission that provides thermoresistive sensing of skin temperature. By integrating the sensor in a wireless optoelectronic patch, we demonstrate closed-loop regulation of light delivery as well as thermal characterization of blood flow. This light delivery and thermal monitoring approach may open opportunities for wearable devices in light-based diagnostics and therapies.

An Implantable Ionic Wireless Power Transfer System Facilitating Electrosynthesis

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 (ρ_gel/ρ_metal ∼ 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.