Tunneling resistance model for piezoresistive carbon nanotube polymer composites

Carbon nanotube (CNT) polymer composites exhibit outstanding electrical conductivity that enables a myriad of sensing and actuation applications. Highly sensitive strain sensors can be realized through piezoresistivity in which a resistance change is induced by mechanical strains. Tunneling conduction between CNTs in close proximity is a major mechanism contributing to the overall piezoresistivity of the CNT network, and is sensitive to the separation distance, lattice registry and the orbital overlap of the interacting CNTs. In this paper, we propose a tunneling resistance model that relate these effects to the CNT chirality, geometry, and orientation. We construct the model based on the distance-dependent Landauer equation, and introduce two additional geometric variables, namely the lattice alignment angle and the axis alignment angle. The tunneling resistance model is incorporated into a CNT network representative volume element to determine the piezoresistivity of the CNT polymer composite. The model reproduces the periodic variation of tunneling resistance consistent with experimental observations and quantum simulations in the literature, and provides improved predictive accuracy of piezoresistivity in CNT polymer composites.