PDMS based capacitive flexible sensors sensitivity to ambient conditions

Abstract

Flexible resistive or capacitive PDMS based sensors have attracted much interest in the last years. Their conformability allows them to be put in contact with unflat and/or deformable structures such as live bodies and monitor contact pressures for several applications, such as wearable sensors, healthcare and human-machine interactions. The sensitivity and pressure range are the most studied features of these sensors. However, sensors output is also influenced by their environment: temperature is especially difficult to assess in the case of wearable sensor, as they are often placed in between a live body and the surrounding air which temperature can vary in a wide range. In this paper, the effect of humidity and temperature on capacitive, PDMS dielectric pressure sensors is presented. In order to mimick operation conditions in contact with live bodies, a dedicated setup has been built and the no-load capacitance of the sensors has been studied for temperatures ranging from 25°C to 50°C and humidity rates from 30 % to 80 %. The results show a relatively low dependence of the measured capacitance on temperature and humidity, compared to that of a commercially available piezoresisitve flexible sensor.