Chemically sensitive field-effect transistor with polyaniline-ionic liquid composite gate

A sensing layer for a chemically sensitive field-effect transistor (CHEMFET) based on a composite of camphorsulfonic acid (CSA)-doped polyaniline (PANI) and the room-temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)-imide, BMI(Tf2N), has been developed and characterized for the sensing of ammonia gas. The work function responses of the cast films with and without IL were analyzed by stepwise changes of ammonia gas concentration from 0.5 to 694 ppm in air as a function of the mole fraction of IL to PANI. The PANI.CSA/BMI(Tf2N) layers showed enhanced sensitivities, lower detection limits, and shorter response times. There is experimental evidence that PANI forms a charge-transfer complex with imidazolium cation.