Polyaniline is an emerging ammonia sensor material

mainly due to its reversible protonic doping-base dedoping property.Though many factors influence the performance of ammonia sensor

this work focuses on the role of relative humidity (RH) on polyaniline ammonia sensor.For RH from 10% to 80%

the relative sensitivity of polyaniline film on ammonia was enhanced with increasing ammonia concentration when it changed from 10 L/L to 2500 L/L

however

when ammonia concentration was less than 400 L/L

no obvious change in relative sensitivity was observed with various RH.At fixed ammonia concentration

for RH above 40% and ammonia concentration over 500 L/L

fast response was observed while relative sensitivity decreased with the increasing RH

which was due to the increasing formation of NH4OH from the reaction of NH3 and H2O at higher humidity.The NH4OH formation reaction was accelerated and response time was shortened since polyaniline was more easier to be doped by NH4OH

while the protonation of water when RH was over 40% reduced the relative sensitivity.Therefore

RH must be considered as one of the important factors for polyaniline ammonia gas sensor.