Threshold detection of carcinogenic odor of formaldehyde with wireless electronic nose

Exposure to volatile organic compounds in the indoor environment is considered as a serious health threat to occupants of buildings. Formaldehyde is one of the major concerns because it is classified as a human carcinogen. It is a ubiquitous compound that is emitted from many household products. The United States Occupational Safety and Health Administration agency has set the short term exposure limit to formaldehyde at 2 ppm. In traditional monitoring methods, air samples are collected from the indoor environment and then specialized staff analyze these samples in the laboratory to identify formaldehyde in the sampled space. These methods cannot be adopted for long-term monitoring due to the long operational cycle and high cost. In this paper, we present a compact wireless electronic nose for formaldehyde recognition. The wireless electronic nose is implemented by integrating an array of 6 metal-oxide gas sensors for acquiring the gas signature and a radio frequency module for wireless communication. Bio-inspired coding is used to differentiate the signature of formaldehyde from other commonly found indoor gases. After identification of formaldehyde, statistical pattern recognition algorithms are used to determine that its concentration level is above or below the short term exposure limit.