Piezoresistive pressure sensor using vertically aligned carbon-nanotube forests

A pressure sensor functionalised with vertically aligned carbon nanotubes is presented. The sensor is fabricated to have a multi-walled carbon-nanotube forest supported by a deflectable 8 m-thick Parylene-C membrane that is suspended by the silicon frame. The responses of the fabricated sensors are experimentally characterised. The sensitivities to positive and negative gauge pressures are found to be comparable in magnitude with the average values of -986 and +816 ppm/kPa, respectively. The measurement also reveals that the temperature coefficient of resistance for the forest suspended with the Parylene membrane is -515 ppm/°C and ~3× smaller than that for the forest fixed onto the silicon substrate.