Table 1.

Advantages and disadvantages of MOX and optical gas sensing technologies when used in WSNs and UAVs.

Category	MOX Sensors		Optical Sensing Techniques
	Advantages	Disadvantages	Advantages	Disadvantages
Aerial missions	Low energy consumption and light weight	Slow sensor response hinder aerial applications	Tested and proved	Energy consumption and weight may limit flight endurance
Ground missions	Tested and proven	Cross reference to different gases and sensitive to humidity	High sampling frequency, high specificity to target gas	No literature found, sensor are too expensive to be left unattended
Continuous release mission	Low energy and light weight, covers wide range of gases	No literature found	High sampling frequency, high specificity to target gas	Energy consumption and weight may limit flight endurance
Instantaneous release	Low energy and light weight, cover wide range of gases	Low sensor response time	High sampling frequency, high specificity to target gas	Energy consumption and weight may limit flight endurance
Computational resources	Few output variables, and same variables remain over large range of gases	No literature found -	No literature found	The number of output variables to measure depends on the optical technique used and target gas
Resolution	Regular resistive sensors achieve ppm resolution	Few sensors achieve ppb resolution	Several techniques achieve ppm and ppb resolution	No literature found
Cost position in Market cost	Low	None	NDIR modules have Low	Complex systems Medium to High