Electron-Beam Patterned Monolayer-Protected Gold Nanoparticle Interface Layers on a Chemiresistor Vapor Sensor Array

Use of electron-beam induced crosslinking (EBIX) to pattern films of thiolate-monolayer-protected gold-nanoparticles (MPNs) on chemiresistor (CR) vapor sensors is described. MPNs with alkyl, cyanoalkyl, phenoxyalkyl, and hydroxyfluoroalkyl thiolate tail groups were patterned on integrated arrays of interdigital electrodes using electron doses of 500-750 μC/cm². The dc resistances of solvent cast films of these MPNs decrease and the baseline-normalized changes in resistance to each of five organic vapors increase to different degrees with increasing electron-beam dose. Relative responses patterns from an array of MPN-coated CR sensors for the test vapors change after EBIX patterning and the diversity of responses is diminished, on average, but it is still projected to be sufficient for the discrimination of most of the individual test vapors and binary mixtures. Results are rationalized in terms of expected changes in ligand structures and film properties following EBIX patterning using known models of electronic conduction, and vapor-induced changes of conduction, through MPN films. The implications of the results for creating arrays of densely packed MPN-coated CRs as detectors for microanalytical systems are considered.