loT is the key to building a smart city, in which sensors act as eyes and ears of the system to collect and convert physical variables into electronic signals for analysis. A self-powered wireless sensing e-sticker, thin as two human hairs, developed by CUHK, converts the power of a finger touch into electromagnetic wave signals to advance the smart sensing technology. Another discovery is a TENG with high power output to better harvest mechanical and biomechanical motion.