Rapid, sensitive, and multiplexed on-chip optical sensors for micro-gas chromatography

• Published in: Lab on a chip 2012-03, Vol.12 (5), p.901-905
• Main Authors: Reddy, Karthik, Guo, Yunbo, Liu, Jing, Lee, Wonsuk, Oo, Maung Kyaw Khaing, Fan, Xudong
• Format: Article
• Language: English
• Subjects: Chromatography; Chromatography, Gas - methods; CMOS; Microarray Analysis; Monitors; Multiplexing; Polymers - chemistry; Reproducibility of Results; Sensor arrays; Sensors; Silicon; Silicon - chemistry; Time Factors; Wafers
• ISSN: 1473-0197; 1473-0189
• DOI: 10.1039/c2lc20922e

We developed and characterized a rapid, sensitive and integrated optical vapor sensor array for micro-gas chromatography (μGC) applications. The sensor is based on the Fabry-Pérot (FP) interferometer formed by a micrometre-thin vapor-sensitive polymer layer coated on a silicon wafer. The thickness and the refractive index of the polymer vary in response to the vapor analyte, resulting in a change in the reflected intensity of the laser impinged on the sensor. In our study, four different polymers were coated on four wells pre-etched on a silicon wafer to form a spatially separated sensor array. A CMOS imager was employed to simultaneously monitor the polymers' response, thus enabling multiplexed detection of a vapor analyte passing through the GC column. A sub-second detection time was demonstrated. In addition, a sub-picogram detection limit was achieved, representing orders of magnitude improvement over the on-chip vapor sensors previously reported.