Table 3.

Overview of PPy used as active layers for detection of ammonia at room temperature.

Polymer Type	LOD	Response Time/Recovery Time	Transducing Mechanism	Ref.
PPy nanoparticles	5 ppm	Less than 1 s/2 s	Chemiresistive	[58]
Multidimensional PPy nanotubes	0.01 ppm	Less than 1 s/55–60 s	Chemiresistive	[113]
Single PPy nanowire	40 ppm	15–10 min (for 40–300 ppm)/15 min for 40 ppm	Chemiresistive	[36]
PPy nanowires	1.5 ppm	60 s for 73 ppm/prolonged with increasing of con. (1.5–73 ppm)	Chemiresistive	[18]
Single crystal PPy nanotube	0.00005 ppm	~16 s/~16 s for 1 ppm	Chemiresistive	[114]
PPy nanoribbons	0.5 ppm	~8 min/3 min	Chemiresistive	[62]
PPy nanotubes PPy/Ag–AgCl composite Nanotubes	–	>1000 s for 100 ppm/−150 s for 100 ppm/500 s	Chemiresistive	[115]
PPy/ZnO nanocomposite PPy/SnO2 nanocomposite	10 ppm	~100 s for 24 ppm/100 s ~50 s for 24 ppm/250 s for first 3 cycles	Chemiresistive	[13]
PPy/graphene nanocomposite decorated with TiO2 nanoparticles	1 ppm	~36 s/~16 s for 50 ppm	Chemiresistive	[116]
Au/PPy nanopeapods	0.007 ppmv	~15 min for 5 ppmv/did not reach Ro value	Chemiresistive	[117]