Stretchable chipless RFID multi-strain sensors using direct printing of aerosolised nanocomposite

Wireless communicated sensors currently play a major role in due to the importance of data for internet-of-things (IoT) devices. Specifically, chipless radio frequency identification (RFID) technology is a widely used technique for communication of data due to its printability, simplicity, and low cost. Here, stretchable and chipless RFID strain sensors were fabricated by direct printing of aerosolized nanocomposites using an aerodynamically focused nanomaterial printing system, which is a direct printing process for conductive and stretchable pattern printing onto flexible substrate. In particular, microscale porous conductive patterns composed of silver nanoparticle and multi-walled carbon nanotube composites were printed onto polydimethylsiloxane. The fabricated sensor exhibited motion with a high degree of freedom, including the ability to be stretched, twisted, or folded. Moreover, it demonstrate a gauge factor >0.5 and maximum strain limit >20 %, with resonance frequency controllability due to regulation of the geometrical properties of LC resonance circuits. Because the original sensor characteristics allowed independent sensing in a single direction, we fabricated an RFID strain sensor that could measure normal strain, as well as shear strain in all directions. Finally, we directly printed the sensor onto air tubes and verified its performance.