From cotton to wearable pressure sensor

In this work, carbon cottons (CC) with moderate electrical conductive (11 S m^-1) were prepared from cotton via a simple pyrolysis process. Flexible and electrical conductive CC/polydimethylsiloxane (PDMS) composites were fabricated by vacuum assisted infusion of PDMS resin into a CC scaffold. Based on the CC/PDMS composites prepared, a simple yet highly sensitive pressure sensor was developed, which shows a maximum sensitivity of 6.04 kPa^-1, a wide working pressure up to 700 kPa, a wide response frequency from 0.01 to 5 Hz, and durability over 1000 cycles. Based on our knowledge, the pressure sensitivity of the CC/PDMS sensor is only next to the record value in a pressure sensor (8.4 kPa^-1). By integrating the pressure sensor with a sport shoe and waist belt, we demonstrate that the real time sport performance and health condition could be monitored. Notably, the device fabrication process is simple and scalable with low-cost cotton as raw material. The CC/PDMS composites are believed to have promising potential applications in wearable electronic devices such as, human-machine interfacing devices, prosthetic skins, sport performance, and health monitoring.