A Feasibility Study of Optical Wireless-based Data and Power Transfer for In-body Medical Devices

One constraint in developing in-body medical devices (IMDs), such as implantable devices, in-body sensors, and others, lies in the power supply, as most of them employ batteries with a limited lifespan. The need for frequent battery replacements increases the physical and psychological burden on patients and imposes additional financial costs. In addition to exploring energy harvesting (EH) for IMDs, it is imperative to further the development of wireless communication mechanisms for these purposes, such as biotelemetry. This paper demonstrates the feasibility of transmitting data and power simultaneously through a single near-infrared (NIR) beam across biological tissue. Our study relies on experimental work under the test-bed, constructed from off-the-shelf components. Our study considered an 810 nm 375 mW NIR LED, a commercial monocrystalline indoor photovoltaic (PV) cell, a 0.52F supercapacitor for energy storage, and utilized a 15 mm thick pure fat porcine tissue sample. The results indicate that a data speed of 95.7 kbps can be achieved using Gaussian minimum shift keying (GMSK) modulation. The PV cell is employed to harvest energy from the same NIR light source and placed close to a photodetector amplifier (PDA) module; the output of the PV cell is connected to a power management integrated circuit (PMIC) operating within a voltage range of 1 V – 4.5V. The supercapacitor can be fully charged under 500 rnA of LED current within approximately 41 minutes. The result of this study is promising, as the combination of wireless charging and communication links using an optical-based approach for various IMDs pave the way for future clinical application advancements.