| Classical gas sensors |
| Chemiresistive metal oxide sensors |
Suitable to wide range of gases Good sensitivity (ppm and sub–ppm) Long lifetime Short response time Mature technology production Low cost, Small size, Easy to use |
Operates in high temperatures Vulnerable to poisoning Humidity sensitive Baseline drift |
| Chemiresistive conducting polymers sensing |
Suitable to wide range of gases Operates at room temperatures Resistant to sensor poisoning Good sensitivity (ppm) Short response time Low cost, Small size, Easy to use |
Temperature and humidity sensitive Limited sensor lifetime Poor selectivity, reversibility and stability Baseline drift |
| Chemiresistive carbon nanotubes and graphene sensors |
Ultra-high sensitivity (ppb) Usually operates at room temperature Fast response and recovery time |
Temperature and humidity sensitive Difficult to fabricate, expensive Poor reproducibility |
| Electrochemical |
Power efficient and robust High selectivity Ambient temperature operation Suitable for toxic gas detection |
Large size Not suitable to wide range of gases |
| Piezoelectric |
Very high sensitivity (ppb) Diverse sensing materials Fast response and recovery times |
Temperature and humidity sensitive Poor signal–to–noise ratio Complex fabrication process |
| Optical |
High sensitivity, selectivity and stability Fast response and recovery times Insensitive to environment change |
Difficulty in miniaturization High cost and high power consumption Low portability |
| MS and GC based e-noses |
| MS |
Insensitive to environment change High sensitivity, stability, reproducibility Resistant to sensor poisoning and baseline drift Well known technology |
Expensive Consume high amounts of power Difficulty in miniaturization Complicated construction |
| GC |
Insensitive to environment change Resistant to sensor poisoning and baseline drift High sensitivity, stability, reproducibility |
Large and heavy Complicated construction Very expensive Require carrier gas Not foreseen for on site applications |
