Environmental Sensors and Subsystems

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On Column Optical Vapor Sensors in Micro-GC Development
Maung Kyaw Khaing Oo, Karthik Reddy, Jing Liu, and Xudong (Sherman) Fan
SERS Probes : Identifying enhanced Raman signal of gas molecules by gold nanostructures (left) and FPC Sensors : Detecting interference shift signal of two reflected beams from Si substrate and polymer-air interface caused by vapor (right)
SERS Probes : Identifying enhanced Raman signal of gas molecules by gold nanostructures (left) and FPC Sensors : Detecting interference shift signal of two reflected beams from Si substrate and polymer-air interface caused by vapor (right)

Traditional gas chromatography tandem with mass spectroscopy system exhibits excellent detection specificity and sensitivity; however, it is bulky and has high power consumption. Applications of on-site, rapid and real time vapor analysis require innovative portable micro-gas chromatography (μGC) systems, which have been under intense study in the past couple of decades. Here, we focused on development of micro-vapor detectors that need to be sensitive, fast in response, small in size, and easily integrated with other μGC components. Fabry-Pérot (FP)-based sensors are robust, and display the potential for mass production and simple integration with current μGC technology. We developed an FP sensor which has gas sensing polymer forms part of the FP cavity. A sub-nano-gram detection limit and sub-second response time were achieved, representing orders of magnitude improvement over those previously reported. However, the FP sensor alone, the signature of vapor is not identifiable. Thus we developed another Surface enhanced Raman scattering (SERS) detector. The metallic nanostructures detector offers powerful means for express identification and trace quantities detection. We demonstrated using of Au nanostructures amplified the small Raman scattering cross section of molecules toward distinguishable signal. The detection limit of 0.4 attogram of 2,4-dinitorluene vapor was achieved. It required only a minute exposure with vapor and 2 seconds detection time.

Updated 04/11/2012