Characterization of polyethelene glycol-coated microcantilever sensors response to ethanol vapor

The research in this thesis centered on the study of the fundamental physical and chemical properties of polyethylene glycol (PEG)-coated, silicon microcantilevers. The properties of the PEG films were examined and correlated to how the film morphologies affect the properties of microcantilever behavior. Microcantilevers experience oscillations that are a result of the displacement of ambient thermal energy. In addition to the resonance frequency shifts of microcantilevers due to adsorbed species, microcantilevers also undergo bending due to differential surface stress. The primary observations resulting from this study were that (i) microcantilevers with the highest mass of deposited PEG experienced the greatest shift in resonance frequency; (ii) PEG films with larger surface areas had the best sensor signal, fast linear response and large deflection voltages when exposed to EtOH; (iii) the PEG coated films have excellent reversibility due to the relatively weak hydrogen bond interactions between PEG and EtOH; and (iv) the adsorption-desorption equilibrium conditions result in pronounced signals with very small amounts of adsorbed EtOH.