A micro helium-discharge photoionization detector for gas sensing

This paper reports a 2cm × 1cm easy-to-micromachine helium discharge photoionization detector (μHeDPID) for use in micro gas chromatography by utilizing a lift-off process. This universal detector consumes a miserly 2.5mW for plasma generation and non-destructively photoionizes analyte compounds, thus avoiding fouling of electrodes. The ionized species is detected by a remote electrode connected to a picoammeter. The detector exhibits at least 350pg and 50ppm detection limit for n-octane in air. Despite the detector simplicity, its efficiency is in par with previously reported destructive plasma detectors which are based on more sophisticated spectrometric analysis.