. 2021 May 14;21(10):3423. doi: 10.3390/s21103423

Table 2.

Material deposition methods, sensing technologies, sensor performance parameters and operating temperatures with various sensing materials and target analytes in gas phase.

Sensing Material	Target Analyte	Sensing Technology	Deposition Method	Material Thickness	Dynamic Range & Limit of Detection	Recovery Time	Operating Temperature	Long-Term Stability	Sensitivity (Output/Input)	Refs.
BMIM-NTf $_{2}$	Ethylene	Amperometric	Drop-coating	63 µm	760 ppb–10 ppm	-	22 °C	-	51 pA/ppm	[35]
Porous ZnO NS	Ethylene	Chemiresistive	Dip-coating	10 nm	5–2000 ppm	20 s	350–500 °C	30 days	0.6 µA/ppm	[43]
LaFeO $_{3}$	Ethylene	Chemiresistive	Screen printing	37–38.3 µm	25–5000 ppm	~1 s	20–200 °C	-	$0.4$ $Ω$ /ppm	[80,81]
SWCNTs	Ethylene	Chemiresistive	-	1 µL	0.5–50 ppm	-	4 °C	16 days	1.2%R/ppm	[45]
SnO $_{2}$ nanoparticles	Ethylene	Chemicapacitive	Dip-coating/Sputtering	1300 nm	20–100 ppm	~10 s	22 °C	-	0.0531 pF/ppm	[27]
PtTiO $_{2}$	Ethylene	Magnetoelastic	Dip-Coating	31–155 nm	0.5–50 ppm	-	19 °C	-	8.5 Hz/ppm	[44]
ZnO	CO $_{2}$	Chemiresistive	Spray pyrolysis	8.3 nm	50–1000 ppm	100 s	300 °C	-	800 $Ω$ /ppm	[48]
PEDOT PSS/graphene	CO $_{2}$	Chemiresistive	Calibrated spreader	10 µm	4.7–4500 ppm	-	35–65 °C	-	0.004–0.0047%R/%RH	[51]
TiO $_{2}$ coated g-C $_{3}$ N $_{4}$ NS	CO $_{2}$	Chemiresistive	Drop-coating	30 nm	100–2500 ppm	35 s	22 °C	60 days	406 $μ$ $Ω$ /ppm	[50]
CeO $_{2}$	CO $_{2}$	Chemiresistive	Drop-coating	170–210 nm diam.	150–2400 ppm	~1 s	100–250 °C	-	$4.88$ $k$ $Ω$ /ppm	[49]
EMIM[NTF $_{2}$ ]	CO $_{2}$	Chemicapacitive	Dip-coating	<1 µm	50,000–1,000,000 ppm	38.5 s	Room temperature	-	29 pF/ppm	[52]
HPTS	CO $_{2}$	Fibre-Optic	Dip-coating	>1 µm	300–300,000 ppm	50–100 s	22 °C	-	0.00055 a.u./ppm	[54]
mPEI	CO $_{2}$	Resonator	Spin coating	-	0.011%	-	-	-	8 Hz/ppm	[29]
CuO,Fe $_{2}$ O $_{3}$	H $_{2}$ S	Amperometric	-	-	10ppm	-	−15 °C–65 °C	-	700 µA/ppm	[57]
CNTs/SnO $_{2}$ /CuO	H $_{2}$ S	Chemiresistive	Spin-coating	>6 nm	10–80 ppm	10 min	25 °C	-	$4.41$ $Ω$ /ppm	[32]
SnO $_{2}$ nanofibres	H $_{2}$ S	Chemiresistive	Electro-spinning	150 nm diam.	0.1–1 ppm	230 s	200–350 °C	-	970 $k$ $Ω$ /ppm	[56]
Zn $_{2}$ SnO $_{4}$ NS	H $_{2}$ S	Chemiresistive	Dip-coating	100 nm	5–1000 ppb	1300 s	133–170 °C	60 days	$1.08$ $M$ $Ω$ /ppb	[59]
In $_{2}$ O $_{3}$	H $_{2}$ S	Chemiresistive	Dip-coating	100 um	5 ppb	5 min	25–100 °C	30 days	$13.02$ $k$ $Ω$ /ppm	[55]
WO $_{3}$ , PPy	H $_{2}$ S	Chemiresistive	-	50–100 nm	200 ppm	>1 day	90 °C	-	490 µV/ppm	[58]
SWCNTs	H $_{2}$ S	Chemiresistive	Spin-coating	1–2 nm diam.	5 ppm–150 ppm	10–15 s	20 °C	-	0.47%R/ppm	[61]
ZnO Nanowires	Ethanol	Chemiresistive	Spin-coating	25 nm diam.	1–200 ppm	120 s	300 °C	-	644 $Ω$ /ppm	[82]
SnS	Ethanol	Chemiresistive	-	-	10 ppm	9 s	200 °C	6 weeks	0.27–13.5%R/ppm	[63]
Pd/TiO $_{2}$	Ethanol	Chemicapacitive	Nanorod growth	710–750 nm	1–100 ppm	2.4–3.8 s	100 °C	-	7.5%C/ppm	[62]
SiO $_{2}$ /Si NW	Ethanol	MGFET	vapor-liquid-sold growth	16 nm diam.	26–2000 ppm	4 min	60 °C	-	16–40 pA/ppm	[64,83]
PSAA	Ethanol	Resonator	Drop-coating	19.9 nm	13.3 ppm	20 min	24 °C	-	1.5 Hz/ppm	[84]
CuO particles	Water Vapor	Chemiresistive	Drop-coating	140 µm	33–90%RH	-	22 °C	-	0.5– 30 $k$ $Ω$ /%RH	[67]
WS $_{2}$ NS	Water Vapor	Chemiresistive	Drop-coating	6 nm	8–85%RH	30–140 s	-	several weeks	580 $M$ $Ω$ /%RH	[75]
MWCNTs-CS	Water Vapor	Chemiresistive	-	-	11–95%RH	-	Room temperature	-	$2.4$ $m$ $Ω$ /%RH	[68]
MWCNTs-PLL	Water Vapor	Chemiresistive	Drop-coating	-	0–91.5%RH	-	Room temperature	-	$3.78$ $k$ $Ω$ /%RH	[68]
MoS $_{2}$ /ND	Water Vapor	Chemicapacitive	-	-	11–97%RH	-	Room temperature	-	6.5 nF/%RH	[74]
SPEEK	Water Vapor	Impedance-based	Drop-coating	20 µm	11–95%RH	130 s	22 °C	30 days	12– 120 $M$ $Ω$ /%RH	[85]
TiO $_{2}$ Nanowires	Water Vapor	Impedance-based	Dip-coating	40–50 nm	12–97%RH	<2 min	17–35 °C	250 days	144 $k$ $Ω$ /%RH	[86]
Silica/di-ureasil FBG	Water Vapor	Fibre-Optic	Dip-coating	450–591 µm	5–95%RH	-	5–40 °C	1 year	1.25–7.14 pm/%RH	[87]
PI	Water Vapor	Fibre-Optic	Dip-coating	450–591 µm	5-95%RH	-	−15–20 °C	-	1.85–2.25 pm/%RH	[88]
Al $_{2}$ O $_{3}$ $^{+}$ /PSS $^{-}$ nano-film	Water Vapor	Fibre-Optic	ESA	84nm	22–39%RH	-	24.5 °C	-	1.43 nm/%RH	[89]
SiO $_{2}$	Water Vapor	Fibre-Optic	ESA	300 nm	20–80%RH	150ms	10–40 °C	-	67.33–451.78 pm/%RH	[90]
CaCl $_{2}$	Water Vapor	Fibre-Optic	-	3 µm	55–95%RH	-	30 °C	-	1.36 nm/%RH	[91]
CoCl $_{2}$	Water Vapor	Fibre-Optic	Drop-coating	10 µm	50–95%RH	~40 s	25 °C	-	67–200 pm/%RH	[92]
HEC/PVDF	Water Vapor	Fibre-Optic	Dip-impregnation	-	40–90%RH	-	28 °C	-	0.196 dB/%RH	[93]
PAA Nanowires	Water Vapor	Fibre-Optic	Electrospinning	-	30–95%RH	210 ms	25 °C	-	0.01 dB/%RH	[94]
ZnO Nanorods	Water Vapor	Fibre-Optic	Dip-coating	2.5 µm	10–95%RH	-	25 °C	-	0.0007–0.0057%P/%RH	[95]
PVA	Water Vapor	Fibre-Optic	Dip-coating	8 µm	20–95%RH	500 ms	20–100 °C	7 days	25–980 pm/%RH	[72,96,97,98]
PEO	Water Vapor	Fibre-Optic	Dip-coating	-	85–90%RH	~1 s	22 °C	-	1.17 dB/%RH	[99]
Silica/methylene blue	Water Vapor	Fibre-Optic	Dip-coating	-	1.1-4.1%RH	<30 s	18 °C	-	0.0087 a.u./%RH	[100]
Ag-Polyaniline	Water Vapor	Fibre-Optic	Dip-coating	15–30 nm diam.	5-95%RH	90s	25–30 °C	-	10–29 mV/%RH	[101]
PGA/poly-lysine	Water Vapor	Fibre-Optic	Soaked in polymer	1 µm	50–92.9%RH	5.8 s	-	-	0.01 dBm/%RH	[102]
ZnO	Water Vapor	Fibre-Optic	Dip/Spin-coating	70–80 nm diam.	5–50%RH	35 s	22 °C	-	0.45%dB/%RH	[103]
Co/Polyaniline	Water Vapor	Fibre-Optic	Dip-coating	10.4 µm	20–92%RH	1 min	30 °C	-	0.024–3.406 mV/%RH	[104]
Gelatin	Water Vapor	Fibre-Optic	Dip-coating	80 nm	9–94%RH	~50 s	22 °C	-	0.167 dBm/%RH	[105]
Chitosan	Water Vapor	Fibre-Optic	Dip-coating	-	20–80%RH	-	25 °C	-	81 pm/%RH	[106]