Carbon Nanotube/PEDOT: PSS Composite-based Flexible Temperature Sensor with Enhanced Response and Recovery Time

Abstract

Temperature sensors with good mechanical flexibility, high sensitivity, fast response and recovery time are essential features for real time measurements by electronic Skin (eSkin). This paper presents the fabrication and characterization of a flexible temperature sensor using PEDOT: PSS and carbon nanotube (CNT) at 1:1 mixing ratio. In order to establish the performance enhancement capability of this composition, a comparative study was carried out. This was done by fabricating two flexible temperature sensors each on $\sim 175 \mu \mathrm{m} -$ thick PVC substrate using only CNT and then with CNT/PEDOT: PSS polymer composite following simple drop casting technique. Both sensors show good sensitivity $\sim 0.27$ (%)$^{\circ}\mathrm{C}^{-1}$)) for CNT and $\sim 0.64$ (%)$^{\circ}\mathrm{C}^{-1}$)) for CNT/PEDOT: PSS for temperatures varying from $20^{\circ}\mathrm{C}$ to $80^{\circ}\mathrm{C}$. Although both the sensors, CNT and CNT/PEDOT: PSS composite revealed fast response and recovery time, the latter shows a higher sensitivity $(\sim 0.64$(%)$^{\circ}\mathrm{C}^{-1}$)). Further, a comparison of the sensor made with CNT/PEDOT: PSS with similar works in literature reveals that the presented sensor exhibits relatively faster response $(\sim 4.8\mathrm{s})$ and recovery $(\sim 2.5\mathrm{s})$ time. This response enhancement can provide a biomimetic eSkin with unique feature.