An intelligent fuel sensor based on a microstructured gas sensor

Temperature cycling of semiconductor gas sensors is a very powerful tool for developing gas detection systems with high selectivity and stability. Microstructured gas sensors - due to their low thermal mass - have very low thermal time constants in the range of 10 ms. Based on these sensors, development of fast and highly selective gas detection systems is possible using temperature cycles spanning the whole operating temperature range with ten or more levels with an overall duration of only a few seconds. I or efficient evaluation of these systems, we have developed a versatile hardware platform which provides accurate control for arbitrary temperature cycles and fast, high resolution data acquisition either in stand-alone operation or connected to a PC Based on this platform, we demonstrate a system for fast discrimination between gasoline and diesel vapors based on a single microsensor and intelligent signal processing. The system is not only able to discriminate steady state conditions but also to correctly classify the transient behavior immediately after exposing the sensor to fuel vapor or ambient air. Integrated in pump nozzles at filling stations the system would allow to prevent the car tank from being filled with the wrong fuel by detecting the type of fuel inside the tank in seconds. For this application micro pellistors are also suitable, which have shown superior stability compared to semiconductor gas sensors.