Chemical microsensors based on smart surface-bound receptors

Abstract

Cyclodextrin thin films were fabricated using either self- assembled monolayers (SAM) or sol-gel techniques. The resulting host receptor thin films on the substrates of surface acoustic wave (SAW) resonators were studied as a method of tracking organic toxins in vapor phase. The mass loading of surface-attached host monolayers on SAW resonators gave frequency shifts corresponding to typical monolayer surface coverage for SAM methods and `multilayer' coverage for sol-gel techniques. Subsequent exposure of the coated SAW resonators to organic vapors at various concentrations, typically 500 parts per millions down to 100 parts per billions (ppb) by mole, gave responses indicating middle-ppb-sensitivity (approximately 50 ppb) for those sensor-host-receptors and organic-toxin pairs with optimum mutual matching of polarity, size, and structural properties.