Improved chemical detection using single-walled carbon nanotube network capacitors

We explore capacitance- and conductance-based detection of trace chemical vapors using single-walled carbon nanotubes (SWNTs). We find that conductance detection is susceptible to such problems as large 1/f noise and incomplete sensor recovery, which are primarily artifacts of a charge-based transduction mechanism. Capacitance detection, dominated by dielectric effects, is less sensitive to charge effects and, thus, offers increased signal-to-noise ratio, improved sensor recovery, and larger dynamic range. Our data indicate capacitance-based sensing with SWNTs is well suited for trace-level detection of such low-vapor-pressure materials as certain chemical warfare agents and explosives.