A fully electronic microfabricated gas chromatograph with complementary capacitive detectors for indoor pollutants

Abstract

This paper reports a complete micro gas chromatography (μGC) system in which all the components are lithographically microfabricated and electronically interfaced. The components include a bi-directional Knudsen pump, a preconcentrator, separation columns and a pair of capacitive gas detectors; together, these form the iGC3.c2 system. All the fluidic components of the system are fabricated by a common three-mask lithographic process. The Knudsen pump is a thermomolecular pump that provides air flow to the μGC without any moving parts. The film heaters embedded in the separation columns permit temperature programming. The capacitive detectors provide complementary response patterns, enhancing vapor recognition and resolving co-eluting peaks. With the components assembled on printed circuit boards, the system has a footprint of 8×10 cm 2 . Using room air as the carrier gas, the system is used to experimentally demonstrate the analysis of 19 chemicals with concentration levels on the order of parts per million (p.p.m.) and parts per billion (p.p.b.). The tested chemicals include alkanes, aromatic hydrocarbons, aldehydes, halogenated hydrocarbons and terpenes. This set of chemicals represents a variety of common indoor air pollutants, among which benzene, toluene and xylenes (BTX) are of particular interest.

Compact prototype microfabricated gas chromatographic analyzer for autonomous determinations of VOC mixtures at typical workplace concentrations

“…Notwithstanding the OPH sensor, the excessive tailing of which renders it of less value as a detector, the speed and resolution obtained were quite good. Taken together with the peak capacities, which ranged from 80 to 103 among the sensors for a 4 min separation based on MBK, and the peak production rates, which ranged from 20-25 per min (also based on MBK), the chromatographic performance of the PEMM-1 exceeds that of other reported GC prototypes employing microfabricated separation components 28,29,[31][32][33][34][35][36][50][51][52][53] .…”

“…Such multi-VOC measurements are currently only possible with portable GCs [1][2][3][4] and transportable FTIR 5 and GC-MS 6,7 instruments, which are too large and expensive for routine evaluations of personal exposures. Although significant advances have been reported recently in the design and development of individual μGC components for preconcentration [8][9][10][11] , separation [12][13][14][15][16][17][18][19][20] ,detection [21][22][23][24][25] , and systems that combine one or more such microdevices with conventional GC components [26][27][28][29] , surprisingly few reports have appeared on integrated and/or packaged μGC systems in which the core analytical components were microfabricated [30][31][32][33][34][35][36] .…”

Gas-phase broadband spectroscopy using active sources: progress, status, and applications [Invited]

“…In addition, standard GC instruments are fairly large with significant electrical power requirements. Some microscale GC components have been fabricated since the 1970s; however, a fully chip-based micro-GC system was only recently demonstrated [342]. By combining this system with chip-based gas cells or miniature cavities as discussed in Section 4.C, the goal of GC-broadband spectroscopy might be achieved.…”

Fabrication of on‐chip vacuum pump using a silicon nanostructure by metal‐assisted chemical etching

“…Pumping systems are necessary in many fields, particularly in microdevices/nanodevices. Pumping techniques are used in various applications, such as using mechanical resonators , optical devices , and gas‐controlling devices . Here, we focus on vacuum pumping.…”