Table 3. The response speed comparison of humidity sensors.

Sensor type	Sensing material	Fabrication method	Hum. & Temp. range (RH, oC)	Recovery & response time	Ref.
SAW	GO	Spin and drop-casting	0.5%–85%, 20–50	<1s, 19 s	This work
Capacitance	GO	Drop-casting	15%–95%, 25	41 s, 10.5 s	4
QCM-type	GO	Spin-coating	6.4%–93.5%, 25	12 s, 18 s	33
Resistance	PDDA/RGO	LbL self-assembly	11%–97%, 25	94 s, 108 s	53
SAW	GO	Droplet by SAW atomizer	5%–100%, 25	n/a	31
Resistance	nanofibre	Drop-casting	5%–80%, 10–50	8 ms, 24 ms	54
Capacitance	polymer	n/a	0%–100%, -40–125	8 s, n/a	8
Impedance	rGO	Spin and drop coating	35%–80%, 20–40	30 ms, 30 ms	23