Development of planar pressure sensors based on SWCNTs and Poly(aniline)

Abstract

Planar flexible pressure sensors were produced with single-walled carbon nanotubes (SWCNTs) and poly(aniline) (PANI) composite. Both materials have been processed as films from liquid suspension onto poly(ethylene) terephthalate (PET) substrate, using indium tin oxide electrodes as lateral electrodes. In this device geometry, the pressure can be applied uniformly to the sensing material, reducing its cross-sectional area, and thus increasing the electrical resistance. After pressure removal, the resistance recovers the initial value, a reversible process that can be used in cycles to monitor pressure variations in larger areas and ranges. This device presents a more linear response when compared with layered pressure sensors, where the sensitivity is commonly limited by the mechanical failure of the bottom/top electrodes. Therefore, this approach can be adapted to produce low-cost pressure sensors that allow the monitoring of larger pressure values (up to ∼ 2.2 MPa). The sensor also responds to lower pressure values being applied in punctual regions, in this case, the electrical resistance drops because the sensor responds as an equivalent parallel resistance.