Research Progress on Humidity-Sensing Properties of Cu-Based Humidity Sensors: A Review

Table 2

Humidity-sensing properties of dopants/CuO.

Dopant	Synthesis method	(°C)	Humidity range	Humidity-sensitive properties				Ref.
				Response time (s)	Recovery time (s)	Hysteresis	Sensitivity
PVP	Polymerization	26.85	25-95 RH	35	12	2.1%	NA	[15]
PEO	Electrospinning	25	30-90%RH	20	11	NA	53837.6%	[77]
PVA	Casting	25	30-70%RH	NA	NA	NA	NA	[78]
PANI	Chemical oxidative polymerization	25	10-95%RH	40	55	NA	70%	[79]
CA	Instrument-less novel technology	25	0-90%RH	13	17	NA	3.8 MΩ/%RH	[80]
Chitosan	Magnetic stirrer	25	20-95%RH	20	50	NA	−0.72to−2.1%RH	[81]
O-B-EG-B	Organic surfactant template	30	5–83.8%RH	180	160	NA	1.25%-7.9%	[82]
ZnO	Solid-state reaction	25	10-95%RH	NA	NA	±4%	29.95 MΩ/%RH	[83]
	Hydrothermal	25	30-90%RH	6	7	21%		[84]
TiO2	Microwave-assisted synthesis	25	10-98%RH	162	428	NA	3.4%	[85]
Cu2O	Heated oxidation	25	35-98%RH	NA	NA	NA	-10.0%	[55]
rGO	Microwave-assisted hydrothermal	25	11-98%RH	2	17	NA	NA	[86]
MWCNT	Electrospinning	25	30-90%RH	3	22	NA	3798.2%	[77]
KCl	WEE	25	11-95%RH	40	50	4%RH	NA	[87]

Note: : operating temperature; NA: not available.