Table 6.

Comparison of the QCM-based formaldehyde sensor parameters. Reprinted with permission from [27]. © 2011 Royal Society of Chemistry.

QCM platform	Sensing structures	Synthesis method of sensing structures	Detection limit (ppm)	Response time (s)	Reference
AT-cut, 6 MHz	Polyaniline-TiO2 nano-composite	Chemical polymerization and sol–gel method	150	–	[261]
AT-cut, 9 MHz	Molecularly imprinted polymers film	Self-assembly and UV light radiation	49	∼270	[268]
AT-cut, 5 MHz	PEI/PVA fibrous membranes	Electrospinning	10	∼800	[250]
AT-cut, 5 MHz	PEI/PS nanoporous fibers	Electrospinning and surface modification	3	∼1000	[244]
AT-cut, 5 MHz	PEI/PA-6 NFN	ESN and surface modification	0.05	<150	[27]