Novel capacitive sensor: Fabrication from carbon nanotube arrays and sensing property characterization

A sandwich-structured gas sensor based on vertically aligned carbon nanotube (CNT) arrays was fabricated and investigated for ammonia and formic acid sensing. Vertically aligned CNT arrays were synthesized by acetone pyrolysis in anodized aluminum oxide (AAO) templates without the use of catalysts. The capacitance change of the sensor with target gas exposure was used as the sensing parameter. The sensor had relatively short response and recovery time. It was completely recovered within 6 min, without requiring any external stimuli. The possible mechanism of the responses was also discussed.