Optical Wireless Data and Power Transfer for In-Body Electronic Devices: A Proof-of-Concept Study Using Ex Vivo Porcine Samples

Abstract

This study presents a proof-of-concept system for the joint wireless transfer of data and power to in-body electronic devices (IEDs) using near-infrared (NIR) light technology. The proposed system addresses two critical challenges in IEDs: the need for enhanced safety, privacy and security on wireless communication to IEDs and the limitations of battery-based power sources. The testbed, built primarily from commercial off-the-shelf (COTS) components, comprises an 810 nm NIR LED, a photovoltaic cell (PV) as an energy harvester, a power management integrated circuit (PMIC), a photodetector amplifier and a supercapacitor. Ex vivo experiments using porcine tissue samples demonstrated three key capabilities: (1) data transmission using Gaussian minimum shift keying (GMSK) modulation, (2) optical power transfer and (3) joint data and power transfer. In terms of data transfer, a data rate of approximately 95 kb/s has been established. Meanwhile, in the context of power transfer, the proposed system successfully charges a supercapacitor across a 3 cm-thick ex vivo porcine tissue within almost one day under 525 mW/cm² light exposure (in a continuous wave operation), harvesting approximately 4.2 J of energy at a rate of 45.64 μJ/s. Furthermore, we have demonstrated wireless charging during data transmission, and it is viable. These results validate the feasibility of using optical links for secure, private, and noninvasive communication to IEDs (i.e., forward biotelemetry), which practically prevents remote hacking activities, as the optical beam coverage is very narrow. Furthermore, with the additional feature of wireless charging capabilities, it potentially reduces the need for surgical battery replacements and is expected to lead to improvements in patient care.