Table 5.

Summary of related FBAR sensors for gas detection

Piezoelectric materials	Device frequency (MHz)	Sensing layer	Target	Limit of detection	Frequency shift	Temp	Year	Ref
AIN	4.8 GHz	CNT/polyethyleneimine	Formaldehyde	24–38 ppb	1.29–1.9 kHz/ppb	RT	2018	[298]
AIN	4.5 GHz	SWCNT/polyethyleneimine	Formaldehyde	82–143 ppb	0.412–0.301 kHz/ppb	RT	2018	[300]
AIN	4.44 GHz	Nine-SAM	VOCs	N/G	n/g	RT	2016	[296]
AIN	4.4 GHz	Polyethyleneimine nanofibers	Formaldehyde	37 ppb.	1.216 kHz/ppb	RT	2018	[297]
ZnO	3.1 GHz	MWCNT/polyethyleneimine	Formaldehyde	50–400 ppb	1.4–2.13 kHz/ppb	RT	2018	[301]
AIN	2.45 GHz	Hybrid thin film	VOCs	40–180 ppb	0.05 kHz/ppm	RT	2019	[302]
AIN	2.4 GHz	MOFs	VOCs	1 ppm	0.28–1.27 kHz/ppm	RT	2020	[303, 304]
ZnO	1.15 GHz	Polyimide	Humidity	15–85%	67.3 kHz/%RH	RT	2020	[280]
ZnO	800 MHz	Ethyl cellulose, poly-siloxanes	CO${}_2$.	50 ppm	N/G	RT	2017	[306]
ZnO	N/G GHz	ZnO	Humidity, ethanol	25–88%	733 kHz/%RH	RT	2017	[305]

N/G Not given