Sensors and actuators based on carbon nanotubes and their composites: A review

With advances in nanotechnology enabling us to structure new materials at the nanoscale, the opportunity exists for developing novel material systems and devices capable of self-sensing and active response. Intrinsic coupling of electrical properties and mechanical deformation in carbon nanotubes makes them ideal candidates for future multi-functional material systems that combine adaptive and sensory capabilities. For development of these material systems with multi-functional constituents for sensing and actuation a fundamental knowledge of their structure/property relations is necessary. In this article, we review some of the recent advances in nanotube and nanotube-based composite sensors and actuators, with a particular emphasis on their electromechanical behavior. The fundamentals of carbon nanotube electromechanical behavior and its application towards the development of nanoscale sensor and actuator systems are first introduced. Then, research on the electrical percolation behavior of carbon nanotube-based composites is reviewed. Finally, the development of carbon nanotube-based composites and their potential use as macroscopic actuators and sensors is highlighted.