Fabrication of highly sensitive field emission based pressure sensor, using CNTs grown on micro-machined substrate

Carbon nanotubes have been used as cold cathode emitter in the fabrication of a sensitive field emission pressure sensor. Vertically aligned carbon nanotubes were grown using the plasma-enhanced chemical vapor deposition (PECVD) on a micro-machined silicon substrate. A silicon membrane was used as the flexible anode against the fabricated CNT-based cathode. A 2-μm thick SiO2 layer has been applied as the anode-cathode spacer and the output results have been compared with a similar sensor with 120 μm spacer. Results show that the sensitivity and the output emission current of the fabricated sensor have been highly improved by decreasing the anode-cathode spacing. Measurements show an ultra-high sensitivity of about 100-970 μA/kPa which is higher than the similar pressure sensors. Low working voltage and high thermal stability of the fabricated sensor are among the other advantages of the presented sensor.