Flexible Printed Carbon-based Sensors and Their Applications

Our research group at Yamagata University in Japan is actively developing flexible and printed organic electronics, covering all related technologies from materials and devices to fabrication processes and applications. Our focus is on wireless applications for healthcare, robotics, and logistics.
We have recently developed highly sensitive and reliable pressure, strain, and humidity sensors using composite materials of carbon and polymeric materials with simple printing methods. The pressure sensor exhibited a high resistivity change with a sensitivity of 0.014kPa-1 when pressure was applied. The stretchable strain sensors demonstrated high sensitivity with a gauge factor of approximately 14 and could stretch up to 100% with small hysteresis. The developed humidity sensors exhibited a high resistive response of 120% over the relative humidity (RH) range of 30% to 90% through an absorption and desorption mechanism, with fast response and recovery times.

We have used these sensors to demonstrate human pulse wave and respiration detection, as well as tactile sensing for robot grippers. In addition, we have established flexible hybrid electronics (FHE) with screen printing methods and combined these sensors with the FHE technology to realize more practical applications for the Internet of Things (IoT) society.