Detection of volatile organic compounds (VOCs) with polymer-coated cantilevers

Changes in the resonance frequency of polymer-coated cantilevers due to gas absorption is shown to be a promising detection mechanism for gases. We prepared SiNx cantilevers based on micromachined Si wafers and used polydimethylsiloxane (PDMS) as polymeric prototype coating. We measured the resonance frequency response of cantilevers end-coated with polymer on exposure to different vapor concentrations of n-octane, toluene. and n-butanole and determined high sensitivities with respect to cantilevers without polymer coating. By using the first higher resonance mode, we found with our configuration sensitivities up to - 0.0988 Hz/ppm for small concentrations of n-octane. It is demonstrated here how the sensitivity of the chemical sensor can be improved by varying the deposited polymer mass. (C) 1999 Elsevier Science S.A. All rights reserved.