Electromechanical behavior and microstructure of highly sensitive polyaniline/ethylene vinyl acetate composite piezo-resistive materials

The unique micro/nano-structure of an intrinsically conducting polymer can be tuned to get higher gauge factors (GF) and reliability, which make them better materials for piezo-resistive applications than conducting carbon based composites and metallic composites. This work reports a highly sensitive conducting polyaniline (PANI)-based composite film that showed a GF ∼66. This high GF was achieved by forming a particular microstructure of conducting PANI particles in a free standing film of PANI-DBSA/EVA. The paper also attempts to explain the mechanism for the observed high sensitivity using the electronic percolation theory, shape and size of the conducting particles and the changes in the microstructure, due to strain. The high sensitivity, high stability during cyclic loading and low electrical hysteresis together with high mechanical strength make PANI-DBSA/EVA conducting composite film a promising material for piezo-resistive strain sensing applications.