Table 2.
All discussed semiconductor metal oxide (SMOs) and organic based sensors.
| Technology | Operating Temp (°C) | Detection Limit (ppb) | Response/Recovery Time (s) | Maximum Response (Rair/Rgas) a | Reference | Selectivity (Max Response/2nd Best Response) | Relative Humidity Tested | Tested on Human Breath? (Y/N) |
|---|---|---|---|---|---|---|---|---|
| MgNi2O3 | 200 | 500 | 25/250 (40 ppm) | 2.3 (10 ppm) | Lavanya et al. [59] | ~1.87 | N/A | N |
| NiTa2O6 | 600 | 200 | 9/18 (2 ppm) | N/A | Liu et al. [61] | ~1.5 | 20–98% | Y |
| PtCu/WO3·H2O HS | 280 | 10 | 3.4/7.5 (50 ppm) | 204.9 (50 ppm) | Deng et al. [56] | ~5.4 | N/A | N |
| PdAu/SnO2 | 250 | 45 | 5/4 (2 ppm) | 6.5 (2 ppm) | Li at al. [48] | ~2.1 | 40–70% | N |
| Cr/WO3 | 250 | 298 | N/A | 71.52 (100 ppm) | Ding et al. [52] | ~4.3 | 25–90% | N |
| Apo-Pt@HP WO3NFs | 350 | N/A | N/A | 88.04 (5 ppm) | Kim et al. [42] | ~2.95 | 90% | Y |
| ZnO QDs | 430 | 100 | N/A | N/A | Jung et al. [43] | N/A | N/A | Y |
| 3DOM ZnO | 320 | 8.7 | 9/16 (1 ppm) | 15.2 (1 ppm) | Liu et al. [54] | ~3.75 | 25–90% | Y |
| Au (2%)/ZnO nanorod | 150 | 5 | 8/5 (100 ppm) | 102 (100 ppm) | Huang et al. [53] | ~3.4 | N/A | N |
| Pd (1.5%)/ZnO nanorod | 150 | 5 | 9/7 (100 ppm) | 69 (100 ppm) | Huang et al. [53] | ~2.6 | N/A | N |
| CdTe/PPY | 24 | 5 | 155/270–310 (5 ppm) | N/A | Šetka et al. [50] | N/A | 30% | N |
| Bi0.9La0.1FeO3 | 260 | 50 | 15/13 (50 ppb) | 40 (100 ppm) | Peng et al. [47] | 5.71 | 55–90% | N |
| ZnO nanoplates | 450 | 45 | 23/637 (50 ppm) | 20 (125 ppm) | Van Duy et al. [66] | 2.22 | 10–80% | N |
| Pt-PH-SO2 | 400 | 200 | 7/(N/A) | 44.83 (5 ppm) | Cho et al. [63] | ~3.57 | 90% | N |
| Si:WO3 | 350 | 20 | 14/36 (100 ppb) | N/A | Righettoni [49] | 18 | 0–90% | Y |
| Catalytic enhanced Si:WO3 | 400 | 50 | 55/100 (500 ppb) | 4.3 (1 ppm) | Weber et al. [81] | 250 | 90% | Y |
a Maximum response recorded without humidity or other interfering gases.