Monitoring trace chemicals in air is a challenging application with many potential solutions to gaining a better understanding of the problem. One approach is to use low-cost chemical sensors, such metal oxide chemiresistors, to detect and quantify chemicals at, for example, point sources like exhaust ports or, as a widely deployed network, around a metropolitan area or an industrial park. However, because these types of sensors are natively broadly selective, useful information relevant to such chemical events can be difficult to extract from their signals. In this presentation, we describe some of our recent work at NIST/Gaithersburg on enabling approaches for the use of electronic-nose (e-nose) type sensors based upon arrays of temperature-modulated chemiresistors. Each sensor element in the e-nose is built upon a microhotplate platform (~ 100 �m across) that enables rapid modulation of the sensor's operating temperature. With each sensor element in a 9- or 16-element array individually addressable, it is possible to tune the e-nose to particular application areas based upon the sensing material and the temperatures used during operation to affect adsorbate-sensor interactions. We demonstrate the tunability of these platforms and some of our enabling operational aspects for several application areas: the detection of volatile small molecules in a complex environment (simulated breath), at low concentrations (between 20 nmol/mol and 200 nmol/mol) in an exotic environment (simulated Martian atmosphere), and at short time scales (less than 10 s) are discussed, along with the relevance to air monitoring.

Tunable electronic noses for monitoring volatile small molecules

246th National Meeting (2013)

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