Development of carbon nanotubes contact-based linear displacement sensor with large sensing range

A novel displacement sensor based on contact area change of two sets of vertically aligned carbon nanotubes (VACNTs) is developed. The VACNTs synthesized on movable side of two facing microstructures are in contact with another set of VACNTs on fixed side. When the movable microstructure is displaced, the VACNTs on movable side slide on those of fixed side. The measured output current signal is linear to the displacement input to the sensor. Experimentally verified sensing range is over 2 mm, and it could be easily extended or reduced by varying the overlapped length of CNTs. By monitoring two signals from two sets of facing VACNTs, it is possible to simultaneously measure both the displacement and the direction of motion. It also enables the significant reduction of possible measurement errors from the temperature fluctuation.