Modeling and experimental analysis of piezoresistive behavior in conductive porous elastomer under significantly large deformation

Piezoresistive porous elastomers (PPEs) are gaining attention in the field of flexible electronics due to their unique properties including ultra softness, ultra lightness, and high sensitivity. These properties can be precisely adjusted through advanced material synthesis and micro/nanofabrication technologies that control the size, shape, and composition of the functional nanoparticles. Despite various theoretical models of porous materials developed to advance the design of these materials, issues such as reverse piezoresistive response and resistance overshooting remains to be unsolved. Using principles of elastic mechanics and electrical tunnel effects, the present study introduces an analytical model that considers the effects of multimodal buckling of the pore wall, pore closure, microcracks, and mismatch within the pore wall under large deformation. The proposed model achieves a 99.5 % accuracy rate in describing the piezoresistive response (stress and resistance) under 75 % compression deformation by incorporating electrical tunnel theory into the mechanical model. The study also uncovers the mechanism behind high resistance overshooting and its relevant influences, including factors such as loading speed and application temperature. These findings are expected to drive the development of better porous composites and pave the way for practical applications of PPEs in various fields of smart sensors.