Effect of single wall carbon nanotube networks on gas sensor response and detection limit

•Effect of SWNT networks on response, signal-to-noise ratio and detection limit has been investigated.•CNT-μR is more sensitive as compared to CNT-TFR.•Regeneration of gas sensor surface and reduction of network density are found to have an adverse effect on the detection limit. In this work Single wall carbon nanotube (SWNT) based gas sensor is fabricated with mainly two type of surface-networks, (i) SWNT random network (CNT-TFR) and (ii) SWNT aligned network (CNT-μR). Investigations of sensor response and its signal-to-noise ratio have been carried out for both the networks. Sensing measurement is performed by exposing sensor to NO2 concentration from 0.5ppm to 20ppm over CNT-TFR and CNT-μR. It has been found that the response of CNT-μR is higher than CNT-TFR. The variation of response with concentration for both sensors is investigated and it is observed that type of surface network affects the surface heterogeneity and hence adsorption capacity of sensor. The detection limit of these gas sensors is 125ppt and 165ppt for CNT-TFR and CNT-μR respectively. CNT-TFR has a better detection limit (DL) and signal-to-noise ratio as compared to CNT-μR due to better surface homogeneity of CNT-TFR. The detection limit for the aligned gas sensors decreases as network density decreases.