Integrated Separation Columns and Fabry-Perot Sensors for Microgas Chromatography Systems

We developed a monolithic subsystem that integrates a microgas chromatography (mu GC) separation column and on-column, nondestructive Fabry-Perot (FP) vapor sensors on a single silicon chip. The device was fabricated using deep reactive ion etching of silicon to create fluidic channels and polymers were deposited on the same silicon chip to act as a stationary phase or an FP sensor, thus avoiding dead volumes caused by the interconnects between the column and sensor traditionally used in mu GC. Two integration designs were studied. In the first design, a 25-cm long mu GC column was coated with a layer of polymer that served as both the stationary phase and the FP sensor, which has the greatest level of integration. This design was capable of sub-second response times and detection limits under 10 ng. In the second design, an FP sensor array spray coated with different vapor sensing polymers was integrated with a 30-cm long mu GC column, which significantly improves the system flexibility and detection sensitivity. With this design, we show that the FP sensors have a detection limit on the order of tens of picograms or similar to 500 ppb with a sub-second response time. Furthermore, the FP sensor array are shown to respond to a mixture of analytes separated by the integrated separation channel, allowing for the construction of response patterns, which, along with retention time, can be used as a basis of analyte identification. [2012-0305]