CMOS Monolithic Nanoparticle-Coated Chemiresistor Array for Micro-Scale Gas Chromatography

Miniaturized detector arrays are critical to reducing size and maintaining measurement quality of integrated micro-gas chromatographs (μGC) used for the analysis of complex vapor mixtures. This paper presents an array of chemiresistors (CRs) with monolayer-protected gold nanoparticle films formed on the surface of a complementary-metal-oxide semiconductor (CMOS) readout chip, featuring high-resolution resistance measurement with adaptive cancellation of baseline resistance. The 8-channel readout circuit occupies 2.2 × 2.2 mm² in 0.5 μm CMOS and consumes 66 μW per channel from a 3.3-V power supply. It achieves a worst-case resolution of 125 ppm over a broad baseline resistance range of 60 kΩ to 10 MΩ, equivalent to 122 dB dynamic range. Implementation of the CMOS monolithic detector array is discussed, and preliminary measurement results using chamber exposures to several vapors are presented. Eventual integration into a μGC is discussed.