Chemiresistive sensor based on polythiophene-modified single-walled carbon nanotubes for detection of NO2

In the present investigation, a chemiresistive sensor based on conducting polythiophene-modified single-walled carbon nanotubes (SWNTs) for NO₂ detection has been reported. The SWNTs were aligned across 3 μm gap between two gold microelectrodes on Si/SiO₂ substrate. Alignment of SWNTs was carried out by using AC dielectrophoretic technique and it was confirmed by current-voltage (I-V) measurement. Aligned SWNTs were modified by conducting polythiophene using charge controlled potentiostatic deposition and it was confirmed by field-effect transistor (FET) and electrochemical measurements. Polythiophene-modified SWNT devices were used for the NO₂ detection in chemiresistive modality. This sensor exhibited very good linear response range from 10 ppb to 10 ppm.