Carbon nanotubes as piezoresistive microelectromechanical sensors: Theory and experiment

Abstract

Carbon-nanotube (CNT) -based strain sensors have the potential to overcome some of the limitations in small-scale force/displacement sensing technologies due to their small size and high sensitivity to strain. A better understanding of the dominant and limiting causes of high strain sensitivity is needed to enable the design and manufacture of high-performance sensor systems. This paper presents the theoretical framework that makes it possible to predict the strain sensitivity of a carbon nanotube based on it chiral indices $(n,m)$. This framework is extended to capture the behavior of sensors composed of multiple CNTs in a parallel resistor network. This framework has been used to predict that a parallel resistor network of more than 100 randomly selected CNTs should have a gauge factor of approximately $78.5\ifmmode\pm\else\textpm\fi{}0.4$. This is within the experimental error of the measured gauge factor of $75\ifmmode\pm\else\textpm\fi{}5$ for such CNT resistor networks.