Polyaniline-NBR blends by in situ polymerization: application as stretchable strain sensors

Stretchable strain sensors in the form of thin films consisting of nitrile butadiene rubber (NBR)/polyaniline (PANI) blends were prepared via in situ polymerization of aniline in the NBR solution. The sensors were characterized for thermal, morphological and piezo-electric properties. Electrical conductivity increased with an increase in filler loading. Piezo resistive measurements showed a decrease in electrical conductivity upon stretching due to disconnection mechanism between filler particles. The piezo resistive properties were evaluated at a strain of 40%. The sensor sensibility was calculated through the gauge factor (GF), and a value of 1.74 was obtained. It was also shown that the GF was a function of the applied strain. The dispersion and distribution was uniform as visualized by SEM analysis. The application of the sensors in human motion detection was demonstrated. The proposed polyaniline-based strain sensors provide an economical alternative to the more expensive carbon nanotube based sensors and can be employed in numerous applications.