From flexible electronics technology in the era of IoT and artificial intelligence toward future implanted body sensor networks

TLDR

Flexible electronics enable sensors that can detect biological signals on the skin and inside the body, yet sustainable energy sources and biocompatible materials remain challenges for fully implanted sensor networks. This review summarizes current flexible and wearable sensors, energy harvesting strategies, and material advances, and outlines future directions toward fully implanted body sensor networks. The authors review recent developments in flexible and wearable sensor platforms, mechanical and thermal energy harvesters, and implantable sensor materials.

Abstract

Flexible electronics technology dramatically changes the capability of sensors, which allows us to detect human biological signals not only on the skin but also inside the human body. Wearable sensors that stick to the skin surface can detect various biomechanical movements, biological signals, and byproducts such as useful elements from sweat and body temperature. On the other hand, implantable sensors directly or indirectly contact with biological components inside the body, such as tissue, organs, or muscles, to support or treat bodily functions or problems. With the development of these advanced sensors, we can live together with a huge number of sensors in the future. Toward body sensor networks that can be fully implanted in the future, sustainable energy sources that support the operation of sensors as well as the development of materials that enable long-term use inside the body remain challenges. In this review, we first summarize various state-of-the-art sensors in terms of flexible and wearable platforms. Additionally, we review the recent research trends of energy harvesters in mechanical and thermal energy conversion into useful electricity for the operation of the sensors. Furthermore, we cover recent studies in the aspect of materials for implantable sensors. Finally, we discuss future direction of the sensors that may enable implanted body sensor networks in the body.