Development of selective and sensitive gas sensors for manhole gas detection

Loss of life of the workers inside manhole is a common problem for many parts of the world. To resolve this issue a portable, low cost, simple manhole gas detection unit has been designed and developed which is capable to detect the poisonous gases like carbon monoxide, hydrogen sulfide, and explosive gas like methane within a minute and raise alarm if the concentration of any gas is beyond the threshold limit. Commercially available sensors were found sensitive, but less selective towards its target gases. To improve the selectivity, the authors have developed ZnO based sensing materials for detecting selectively methane, carbon monoxide and hydrogen sulfide from a mixture of gases. The materials were found highly sensitive and selective towards its target gases at either room temperature or at low operating temperature around 100°C. Different surface activation processes like plasma treatment, composite materials were used to enhance the selectivity of the sensing materials.