Optical Wireless Communications for In-Body and Transdermal Biomedical Applications

This article discusses the fundamental architectures for optical-wireless-systems for biomedical-ap-plications. After summarizing the main applications and reporting their requirements, we describe the characteristics of the transdermal and in-body optical channels (OCs) as well as the challenges that they impose in the design of communication systems. Specifically, we provide three possible architectures for transdermal communications, namely electro-optical monitoring, opto-electrical, and all-optical (AO), for neural stimulation, which are currently under investigation, whereas for in-body communications, we provide a nano-scale AO concept. For each architecture, we discuss the main operation principles, the technology enablers, and research directions for their development. Finally, we highlight the necessity of designing an infor-mation-theoretic framework for the analysis and design of the physical and medium access control layers, which takes into account the channels' characteristics.