Development and improvement of carbon nanotube-based ammonia gas sensors using ink-jet printed interdigitated electrodes

Gas sensors have been widely used in many applications including environmental monitoring, industrial control, and detection in warfare or for averting security threats. High sensitivity, selectivity, and fast response time are required for application in real-time monitoring and detection of toxic gases. Single-walled carbon nanotubes (SWCNTs) provide large specific surface area beneficial for gas adsorption thereby increasing sensor sensitivity. In this paper, ammonia (NH₃) gas sensors based on SWCNTs were developed using interdigitated silver electrodes printed with nanoparticulate ink on alumina substrates. Simple and inexpensive methods including shaking and dispersion in appropriate solvents were used to debundle SWCNTs for improving sensor response. The fabricated sensors showed a maximum response of 27.3% for 500 ppm NH ₃ at room temperature. Detection limit of the sensor devices at room temperature were estimated to be ∼ 3 ppm.