Carbon nanotube based gas sensor for expiration detection of perishable food

With increasing pressure on food industry to reduce waste while meeting the demand for high food quality and safety, there is a strong motivation for research into sensors for monitoring freshness and general food quality. Degradation of fresh meat and produce is related to metabolic activities of microorganisms which commonly result in formation of gaseous compounds such as CO₂. Monitoring the freshness and quality of the food can therefore be accomplished by monitoring the release of these gases in the food package. In this study, an approach to create sensors for detecting gases released by perished food is described. Sensor test is conducted with CO₂ which is a common gas related to the degradation process of food. The sensor is based on Carbon Nanotubes (CNTs) as sensing elements. A local synthesis technique is used to directly integrate the CNTs onto silicon-based circuits at room temperature. Fabricated CNT-based structures have successfully demonstrated the ability to detect CO₂. The sensitivity and selectivity of gas sensors to different gas compounds were also studied. The results indicate that this approach is promising for fabrication of CNT-based gas sensors at low cost for determination of food freshness and quality, making possible complete gas sensors including CNT sensing elements, CMOS signal processing and RF communication on the same chip, manufactured and integrated at the wafer-level scale.