μGC × μGC microsystem with resistive and optical detection

The integration of microfabricated chemiresistor (CR) and micro-optofluidic ring resonator (μOFRR) sensors with other microfabricated components to yield a microsystem capable of performing comprehensive two dimensional gas chromatography (μGC × μGC) is described. Two CRs with different monolayer protected Au nanoparticle (MPN) interface layers were tested along with one μOFRR with a PDMS interface layer. All three provided modulation numbers similar to those of a reference flame ionization detector (FID). Modulated peak widths (full width at half maximum, fwhm) for the CR detectors ranged from 0.31 to 1.9 sec, and those for the μOFRR ranged from 0.24 to 1.2 sec. Although these fwhm values were greater than those from the FID and they increased with the vapor pressure of the analyte, most were <; 1 sec and all peaks were narrow enough to permit efficient μGC × μGC separations. Analyses of mixtures of 6-18 volatile organic compounds are demonstrated.