Helium plasma based gas detectors for volatile organic compounds

A typical configuration of μGC includes a carrier gas source, preconcentrator, separation column, gas detector, pump, valves, and software system. The design of the micro gas detector is critical for the success of μGC systems.<br><br>This thesis presents a new micro helium dielectric barrier plasma discharge-based photoionization detector (μHDBD-PID) using a combination of 3D printing technology and Glassomer^TM material.

The μHDBD-PID successfully achieved the detection and identification of different classes of VOCs (straight-chain alkanes, aromatics, and polar organic compounds) based on the change in light intensity converted from plasma colour change after sample injection. A minimum limit of detection (LoD) of 10 ng for benzene was achieved. Furthermore, the μHDBD-PID was coupled with a Hamamatsu C12880MA mini spectrometer and created a μHDBD optical emission spectra (μHDBD-OES) detection system for the identification of VOCs.

The best LoD of the μHDBD-OES system is about 19 ng for benzene. Finally, a preconcentrator coated with a metal-organic framework (HKUST-1) was manufactured to further improve the detection limit. The detector was able to detect 10 ppm of methane in a calibrated air sample after enrichment performed by the preconcentrator, demonstrating the potential of our detector for practical applications.<br><br>