Modeling and characterization of the transient performance of a gas detector based on fringe-field capacitance

This paper presents the first comprehensive assessment of the transient performance of a gas detector (chemicapacitor) based on fringe-field capacitance using detailed computational modeling and experimental validation. Intended for use with a micro-gas chromatograph (μGC), this 1 mm² detector is comprised of interdigitated thin-film metal electrodes that are patterned on a glass substrate and covered with 0.5-4 μm thick polymer. The model couples gas flow, vapor diffusion with partitioning, and capacitance response. The computational results illustrate the dynamic process of vapor peaks passing through the detector. The existing design provides ≈ 0.06 fF/ng sensitivity for n-pentane, and fast response with ≈ 0.1 s peak broadening, which are appropriate for the μGC applications under consideration. The performance is experimentally validated.