Table 2.

Advantages and disadvantages of e-noses techniques of analysis

Analysis Techniques	Advantages	Disadvantages	Bibliography
colorimetric sensor assays	Fast and cheap	Reproducibility of printing and imaging	[55]
	Easy to use	Stability
	Small sample size	Difficult to determine the exact composition of
	Customization for specific analysis	a mixture
	Versatile-liquid or gas samples	Extensive data set analysis using chemometric
	can be integrated in smart phones	methods
conductive polymer gas sensors	Easy to adjust the sensitivity of the sensor	Long time storage in the air makes them	[56]
	Operated at room temperature	instable
	High sensitivity	Low selectivity
	Easy fabrication
quartz microbalance sensor array	Robust performance	Moderate reproducibility	[57]
	Simple construction	Complex manufacture
	Sensitive detection	Sensitive to humidity and temperature
	Versatile
metal oxide sensors	High sensitivity	High-temperature operation	[58]
	Rapid response	Sensitive to sulfur, low acids, and humidity
		Limit sensor coating
		Low precision