Electronic Nose Technologies in Monitoring Black Tea Manufacturing Process

Table 2

Summary of different gas sensors used in the e-nose system.

Sensor Id	Main compound	References
MQ 7	CO, H2, LPG, CH4, alcohol	[18]
MQ 3	Alcohol, benzene, hexane, LPG, CO, CH4
MQ 4	LPG, CH4, H2, CO, alcohol, smoke
MQ 6	LPG, H2, CH4, CO, alcohol
MQ 9	LPG, CO, CH4
MQ 8	H2, alcohol, CO, CH4
TGS 832	R-12, R-22, R-134 a	[22, 25, 29, 31, 63]
TGS 823	Methane, CO, isobutane, n-hexane, benzene, ethanol, acetone	[22, 25, 29, 63, 64]
TGS 831	R-21, R-22	[25, 31, 63]
TGS 816	CO, CH4, ethanol, propane, iso-butane, H2	[25, 63, 64]
TGS 2600	Methane, CO, isobutane, ethanol, H2	[22, 25, 29, 31, 63]
TGS 2610	Ethanol, H2, isobutane, methane, propane	[22, 25, 29, 31, 63]
TGS 2611	Ethanol, H2, isobutane, methane	[22, 25, 29, 31, 63]
TGS 2620	CH4, CO, isobutane, H2, ethanol	[25, 28]