We describe chemical sensors based on selective sorption in zeolite thin films on piezoelectric devices. Zeolite crystals with different pore sizes were coupled onto the gold electrodes of quartz crystal microbalances (QCM), via molecular attachment on the surface. A self-assembled monolayer of thiol-alkoxysilane coupling agent on the gold surface was used to attach the zeolite crystals to the QCM, and the resulting films were coated with thin glass layers. The sorption behavior and selectivity of the devices was determined via dynamic vapor sorption isotherms, and nitrogen sorption isotherms at liquid nitrogen temperature. Uptake of molecules small enough to enter the zeolite pores can be one hundred times greater than that of molecules with kinetic diameters greater than the pores. The selective adsorption can be tailored by variation of the zeolite composition, pore sizes, and other parameters. The selectivity of these stable films was further controlled by ion exchange into the film. We will compare the above films with recently discovered, oriented zeolite films grown on organic multilayers on gold.1
展开▼
