Comprehensive evaluation of the piezoresistive behavior of carbon nanotube-based composite strain sensors

Abstract

Theoretical analysis of the piezoresistive behavior of carbon nanotube (CNT)-based composites is of great importance for understanding the electro-mechanical response of CNT-based composite strain sensors. In this paper, a comprehensive analytical model is developed to predict the electro-mechanical response of conductive CNT-based composite sensors by considering some critical factors, such as CNT dimensions, interphase, nanotube waviness, and dispersion state. To acheive this, stretching-induced changes in electrical resistance are characterized in the model by the variation of CNT content, CNT orientation, and percolated conductive networks. Then the effects of these key factors are systematically examined on the piezoresistive response of CNT-based composite strain sensors and found to play important roles in determining the sensitivity. Moreover, comparisons between modelling predictions and existing numerical and experimental data are made to demonstrate the validity of the developed model. The developed model highlights the physical mechanism and takes full consideration of the key parameters, which can help to gain a deeper understanding of the piezoresistive behavior of CNT-based composite sensors compared with existing modellings. Finally, a meaningful recommendation is made to optimize the design of highly sensitive CNT-based composite sensors.