Enhanced electromechanical response of nonpercolating polymer-nanoparticle composite films

We have prepared semiconducting carbon nanoparticle polyimide composite thin film with spatially distributed localized energy states exhibiting three-dimensional variable range hopping electron transport. Applied strain (compression or extensional) introduces proportional variations in the spacing between these energy states, as demonstrated in the linear variation of measured electrical resistance. The electromechanical sensitivity is the same in both deformation modes due to this underlying operating mechanism, enabling quantitative measurement of torsional deformations also. Electrical responses across all deformation modes remained in phase with applied strain indicating negligible hysteresis and an ability to operate over a wide strain ranges up to 40 000 microstrains. (C) 2008 American Institute of Physics.