First-generation hybrid MEMS gas chromatograph

Abstract

The fabrication, assembly, and initial testing of a hybrid microfabricated gas chromatograph (microGC) is described. The microGC incorporates capabilities for on-board calibration, sample preconcentration and focused thermal desorption, temperature-programmed separations, and "spectral" detection with an integrated array of microsensors, and is designed for rapid determinations of complex mixtures of environmental contaminants at trace concentrations. Ambient air is used as the carrier gas to avoid the need for on-board gas supplies. The microsystem is plumbed through an etched-Si/glass microfluidic interconnection substrate with fused silica capillaries and employs a miniature commercial pump and valve subsystem for directing sample flow. The latest performance data on each system component are presented followed by first analytical results from the working microsystem. Tradeoffs in system performance as a function of volumetric flow rate are explored. The determination of an 11-vapor mixture of typical indoor air contaminants in less than 90 s is demonstrated with projected detection limits in the low part-per-billion concentration range for a preconcentrated air-sample volume of 0.25 L.

Carbon Nanotube Stationary Phase in a Microfabricated Column for High-Performance Gas Chromatography

“…These drawbacks have hindered miniaturization of GC instruments for which a wide range of applications is foreseen [1]. Recent developments in the micro-fabrication of GC systems using micromachining technology have demonstrated the potential for reductions in size, power consumption, and analysis time compared to conventional GC systems [2][3][4][5][6][7].…”

“…The development and optimization of individual micromachined modules is the current trend in GC miniaturization [2]. Numerous studies have focused on miniaturizing the separation columns to develop micro-GC columns that can quickly separate samples with high efficiency [3][4][5][6].…”

Microscale Gas Chromatography with Microsensor Array Detection: Challenges and Prospects

“…Research and development on microscale gas chromatographic (μGC) systems for analyzing mixtures of volatile organic compounds (VOCs) conducted over the past few decades has produced some significant advances in component device designs, system integration strategies, and performance [1][2][3]. Yet, early projections of inexpensive, pocket-sized instrumentation capable of autonomous, quantitative analysis of airborne VOC mixtures remain unrealized.…”

All Silicon Micro-GC Column Temperature Programming Using Axial Heating

“…Sandia National Lab was the first to integrate a gas chromatography (GC) column, preconcentrator, and chemical sensor arrays into a hybrid system for fast detection of specific analysis commonly present in chemical warfare. Chia-Juang Lu [3] developed the first-generation hybrid MEMS gas chromatograph system, which uses air as the carrier gas and an anodic bonding technique for sealing the silicon etched column to a Pyrex glass. In this system the temperature is regulated using a Kapton embedded resistive wire, with the heat generated by the wire conducted to the bottom of the column.…”