Nano electromechanical sensors based on carbon nanotubes

Sensors are key components in an overwhelming wealth of systems for industrial and consumer applications. Further system miniaturization will demand for continuous down-scaling of sensor functions in such systems most likely towards nanoscale. Then new sensor device concepts will emerge to improve performance, e.g. sensitivity, or to utilize unique functional properties of nanoscale structures. This paper presents concepts and demonstrators of nano electromechanical sensors based on carbon nanotubes (CNTs). First, different transducer concepts based on the unique electrical, mechanical and electromechanical properties of single-walled carbon nanotubes (SWNTs) are addressed and discussed. Second, fabrication techniques and methods for the integration of SWNTs in micro or nanosystems are presented. Finally, demonstrators of suspended SWNT-based cantilever structures and a membrane-based nanotube pressure sensor are introduced and evaluated. Electromechanical measurements on these test devices prove SWNTs as exceptional piezoresistive electromechanical transducers with gauge factors far above the values of state-of-the-art strain gauges. (C) 2007 Elsevier B.V. All rights reserved.