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. 2019 Dec 24;20(1):120.
doi: 10.3390/s20010120.

A MEMS-Enabled Deployable Trace Chemical Sensor Based on Fast Gas-Chromatography and Quartz Enhanced Photoacousic Spectoscopy

Stefano Zampolli  1 , Sandro Mengali  2 , Nicola Liberatore  2 , Ivan Elmi  1 , Luca Masini  1 , Michele Sanmartin  1 , Roberto Viola  2
Affiliations

A MEMS-Enabled Deployable Trace Chemical Sensor Based on Fast Gas-Chromatography and Quartz Enhanced Photoacousic Spectoscopy

Stefano Zampolli et al. Sensors (Basel). .

Abstract

This paper reports on a portable selective chemical sensor for hazardous vapors at trace levels, which combines a two-stage purge and trap vapor pre-concentration system, a Micro-Electro-Mechanical-System (MEMS) based fast gas-chromatographic (FAST-GC) separation column and a miniaturized quartz-enhanced photoacoustic spectroscopy (QEPAS) detector. The integrated sensing system provides two-dimensional selectivity combining GC retention time and QEPAS spectral information, and was specifically designed to be rugged and suitable to be deployed on unmanned robotic ground vehicles. This is the first demonstration of a miniaturized QEPAS device used as spectroscopic detector downstream of a FAST-GC separation column, enabling real-world analyses in dirty environments with response time of a few minutes. The main modules of the GC/QEPAS sensor device will be described in detail together with the system integration, and successful test results will be reported and discussed.

Keywords: CBRN; MEMS GC; QEPAS; forensic; safety and security.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Sensing chain of the gas-chromatographic (GC)/quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor.
Figure 2
Figure 2
First stage sampling and pre-concentration module.
Figure 3
Figure 3
A packed Micro-Electro-Mechanical-System (MEMS) pre-concentrator (left) with backside integrated heater and temperature sensor, MEMS fast gas-chromatographic (FAST-GC) column (center, L = 5.3 m) and GC column heater chip (right). The scale unit is centimeters.
Figure 4
Figure 4
GC module integrating a 6-port valve inside an Aluminum oven with PEEK thermal insulation, with an internal view of the injector oven (left) and a close-up on the MEMS pre-concentrator and its temperature control electronics (right). The MEMS FAST-GC column is mounted on the other side of the oven (not visible).
Figure 5
Figure 5
QEPAS module (a) and miniaturized QEPAS cell ((b), scale unit centimeter).
Figure 6
Figure 6
The complete GC/QEPAS sensor, open (left) and packaged (right).
Figure 7
Figure 7
Total absorption chromatogram (a) and DPGME spectrum acquired at T = 154 s compared with the library spectrum (b).
Figure 8
Figure 8
Total absorption chromatogram (a) and DMME spectrum acquired at T = 130 s compared with the library spectrum (b).
Figure 9
Figure 9
Total absorption chromatogram (a) and MS spectrum acquired at T = 193 s compared with the library spectrum (b).
Figure 10
Figure 10
Total absorption chromatogram (a) and sulfur mustard HD spectrum acquired at T = 210 s (b).
Figure 11
Figure 11
Total absorption chromatogram (a) of a 3-component mixture, and the correctly identified spectra of Propanol, DMMP and dipropylene glycol methyl ether (DPGME) at the respective retention times (b–d).
Figure 12
Figure 12
Color plot of all spectra acquired for the mixture of propanol, DMMP and DPGME.
Figure 13
Figure 13
DMMP with strong gasoline background: total absorption chromatogram (a) and DMMP spectrum acquired at T = 130 s (b).
See this image and copyright information in PMC

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