Progressive Cellular Architecture in Microscale Gas Chromatography for Broad Chemical Analyses

• Published in: Sensors (Basel, Switzerland) Vol. 21; no. 9; p. 3089
• Main Authors: Liao, Weilin, Zhao, Xiangyu, Lu, Hsueh-Tsung, Byambadorj, Tsenguun, Qin, Yutao, Gianchandani, Yogesh B
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 29-04-2021; MDPI
• Subjects: Alcohols; Alkanes; Carrier gases; Chromatography; Connectors; Environmental monitoring; Esters; Flame ionization detectors; Footprints; Gas chromatography; Gas flow; Homology; microvalve; National security; phosphonate ester; Phosphonates; Retention; sampling; Sensors; Separation; Silicon wafers; Subsystems; Valves; vapor; Vapor pressure; VOCs; volatile organic compound; Volatile organic compounds; Volatility; phosphonate ester; microvalve; vapor; volatile organic compound; sampling
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s21093089

Gas chromatography is widely used to identify and quantify volatile organic compounds for applications ranging from environmental monitoring to homeland security. We investigate a new architecture for microfabricated gas chromatography systems that can significantly improve the range, speed, and efficiency of such systems. By using a cellular approach, it performs a partial separation of analytes even as the sampling is being performed. The subsequent separation step is then rapidly performed within each cell. The cells, each of which contains a preconcentrator and separation column, are arranged in progression of retentiveness. While accommodating a wide range of analytes, this progressive cellular architecture (PCA) also provides a pathway to improving energy efficiency and lifetime by reducing the need for heating the separation columns. As a proof of concept, a three-cell subsystem (PCA3mv) has been built; it incorporates a number of microfabricated components, including preconcentrators, separation columns, valves, connectors, and a carrier gas filter. The preconcentrator and separation column of each cell are monolithically implemented as a single chip that has a footprint of 1.8 × 5.2 cm
. This subsystem also incorporates two manifold arrays of microfabricated valves, each of which has a footprint of 1.3 × 1.4 cm
. Operated together with a commercial flame ionization detector, the subsystem has been tested against polar and nonpolar analytes (including alkanes, alcohols, aromatics, and phosphonate esters) over a molecular weight range of 32-212 g/mol and a vapor pressure range of 0.005-231 mmHg. The separations require an average column temperature of 63-68 °C within a duration of 12 min, and provide separation resolutions >2 for any two homologues that differ by one methyl group.