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

摘要

We developed a monolithic subsystem that integrates a microgas chromatography $(mu{rm GC})$ separation column and on-column, nondestructive Fabry-Pérot (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 $mu{rm GC}$. Two integration designs were studied. In the first design, a 25-cm long $mu{rm GC}$ 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 $mu{rm GC}$ 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 ${sim}{rm 500}~{rm ppb}$ 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]