Design and construction of a portable e-nose system for human exhaled breath VOC analysis

This paper describes the design and fabrication of a system that can analyze the human exhaled breath volatile organic compounds (VOCs). The expelled breath contains several VOCs in addition to nitrogen, oxygen, carbon dioxide, and water vapor. Some of these VOCs are biomarkers for certain lung diseases like lung cancer, cystic fibrosis, chronic obstructive pulmonary disease (COPD), etc, and they can even identify smokers and non-smokers by variations of VOCs. The development of the electronic nose (e-nose) with five metal oxide semiconductor (MOS) gas sensors, control circuit, and processing circuit is explained in this paper. The system is tested and verified in the detection of breath VOCs. The clinical feasibility of the system is checked in a small pilot study involving 4 lung cancer patients, 4 chronic obstructive pulmonary disease patients, 4 asthma patients, and 4 healthy controls including smokers and non-smokers. The results of the study are also included, along with the conclusions drawn from the work. The e-nose system developed with TGS gas sensors is economical and uses a non-invasive method of breath sampling, and surely it will be a diagnostic tool for the detection of lung cancer, COPD, and other major respiratory diseases in near future.