Powering Smart Wireless Implantable Medical Devices: Toward an internet of self-powered intra-body things

A new generation of miniaturized, less invasive, and Smart Wireless Implantable Medical Devices (SW-IMDs), designed for real-time monitoring of biomarkers and with real-time system reconfiguration can now be realized thanks to advances in low-power electronics, sensing, wireless communications, and materials. However, the need for long-term and reliable power supply, together with the need to support innovative functions, impose new powering requirements that cannot be satisfied by traditional batteries. Batteries have in fact a major impact on the size and lifetime of the implant, and often need to be replaced every 5–10 years through a surgical procedure, causing discomfort and risks for the patient.

This article provides a broad overview of the two main approaches to powering for future medical implants, namely remote energy transfer and energy harvesting. We describe the underlying physical principles that regulate the energy transfer processes and the energy conversion mechanisms used to transform the energy produced by human or environmental sources into electrical energy. We also offer an extended overview of state-of-the-art technologies, leading remote powering methods, harvesters and scavengers. Some of the most recent prototypes and clinically available devices are briefly described as well. For each technology, we discuss advantages and drawbacks; as well as safety exposure limits to the radiating sources. Finally, we outline a number of open research challenges that need to be overcome to enable a new generation of self-powered implantable medical devices.