Wearable and Implantable Light-Emitting Diodes and Their Biomedical Applications

Light-mediated healthcare, including monitoring and therapy techniques, has evolved significantly over the past decades, owing to their advantages in minimal invasiveness and relatively low side effects. However, most of the clinically available light sources have suffered from their bulky size and rigidity, making them impractical for continuous on-body-type health monitoring and treatment applications. Recently, wearable and implantable healthcare systems using deformable light emitting diodes (LEDs) have been developed, which can be seamlessly integrated to any part of the body and exhibit the potential to improve efficacy of personalized and mobile photo-medicine. In this review, we discuss recent advances in wearable and implantable LED technologies for various biomedical applications. First, we present an overview of the state-of-the-art high-performance wearable and implantable LEDs, especially focusing on their light-emitting materials and unique device design approaches. We also discuss strategies for integrated light-based healthcare systems. Then, we discuss prominent examples of light-medicated sensing and therapeutic applications, whose accuracy and efficacy can be enhanced by wearable and implantable LEDs, ranging from non-invasive oxygen level sensing to various phototherapies. Finally, we conclude this review with a brief outlook on the future technologies.