Abstract
The gas sensing mechanisms, response, and behaviour of a real and a virtual solid-state chemical gas sensor operating either in static or in dynamic mode have been compared. The analysis was done by exposing simultaneously both sensors to different concentrations of various volatile organic compounds diluted in dry, as well as humid, synthetic air. The results revealed similar responses and behaviours for both types of measurement modes when the sensors were exposed towards single gas compounds, but a sensitivity enhancement in measurements comprising mixtures of gases when the sensors were operated in dynamic mode. The method used is able to overcome surface saturation problems and is beneficial for applications where mixtures of gases diluted in relative humidity are present.
Highlights
The concept of using an array of sensors to improve the selectivity of chemical gas sensors by emulating the human olfactory system was developed by W.F
This strategy, called electronic nose [2,3,4], has been implemented in several different ways until nowadays, either by using an array of real sensors based on different sensing materials operating in static mode [5,6,7], that means constant temperature or bias, or by using a single sensor in dy namic operation mode [8,9,10], e.g., working in repeated cycles that include a customized range of temperature variations, which is equiv alent to an array of virtual sensors [11]
The benefits of using a virtual sensor array in comparison to an array of real sensors are notable in terms of cost, robustness, ease of fabrica tion and integration, as this method allows to use one real sensor instead of several
Summary
The concept of using an array of sensors to improve the selectivity of chemical gas sensors by emulating the human olfactory system was developed by W.F. The data treatment and the interpretation of re sults in dynamic operation mode are more complex when compared to static mode. Despite this added complexity, the dynamic operation strategy provides a selectivity enhancement that cannot be achieved with static operation. For this reason, if the purpose is to improve the selectivity of a chemical gas sensor avoiding modifications on the sensing material or on the gas sensing system, the choice is clear
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