Fully Printed and Flexible Carbon Nanotube Transistors for Pressure Sensing in Automobile Tires

As the need for an increased supply and diversity of sensors expands, printed electronics have been identified as a promising approach for low-cost, ubiquitous sensor networks. In this paper, we demonstrate the use of a fully printed carbon nanotube thin-film transistor (CNT-TFT) for sensing environmental pressure over a pressure range extending from 0 to 42 PSIg. The transconductance of the CNT-TFT was found to be linearly correlated with environmental pressure at a sensitivity of 48.1 pS/PSI. We also demonstrate the capability of wirelessly transmitting the data measured by the pressure sensor using a simple Bluetooth module. Using the Bluetooth system, we observed the sensor's response over time as pressure was dynamically changed. Finally, we packaged the sensor along with a material thickness sensor (developed in previous work) into a fully printed smart tire sensor system capable of mapping tire pressure and tread depth differentials.