no 2 at room temperature were investigated with custom system described previously these sensors were challenged with concentrations of no 2 ranging from 100 ppb v to 10 ppm v with 15 minute expose and recovery rimes and the transient are shown in fig7 a the sensor response was determined by the resistance change and defined as r f u2212 r 0 r 0 100 and is shown in fig5 b as a function of analyte concentration r f is the final resistance at 95 of the peak height and r 0 is initial baseline resistance prior to analyte exposure the response time is defined as the time for the sensor to reach 75 of its steady state value the recovery time is identified as the time required for the sensor after the exposure to return to 50 of its maximum response in accordance with an exemplary embodiment the response and recover times are depicted as a histogram in fig5 c with response times ranging from 0 5 to 7 minutes and recovery times ranging 7 to 20 minutes for 100 ppb v no 2 for example in nearly all cases te functionalization improved response recovery time with respect to the swnt network in addition in terms of sensitivity the smaller te charge densities can display near negligible change.