Flexible and stretchable photodetectors and gas sensors for wearable healthcare based on solution-processable metal chalcogenides

Wearable smart sensors are considered to be the new generation of personal portable devices for health monitoring. By attaching to the skin surface, these sensors are closely related to body signals (such as heart rate, blood oxygen saturation, breath markers, etc.) and ambient signals (such as ultraviolet radiation, inflammable and explosive, toxic and harmful gases), thus providing new opportunities for human activity monitoring and personal telemedicine care. Here we focus on photodetectors and gas sensors built from metal chalcogenide, which have made great progress in recent years. Firstly, we present an overview of healthcare applications based on photodetectors and gas sensors, and discuss the requirement associated with these applications in detail. We then discuss advantages and properties of solution-processable metal chalcogenides, followed by some recent achievements in health monitoring with photodetectors and gas sensors based on metal chalcogenides. Last we present further research directions and challenges to develop an integrated wearable platform for monitoring human activity and personal healthcare.