Unusual behavior of uncoated thick-film PZT cantilevers towards fluid phases sensing. Application to water and ethanol detection

Detection of water and ethanol vapors is successfully performed using the 31-longitudinal mode of uncoated Au/PZT/Au cantilevers giving respectively negative and positive resonance frequency shifts. Differences between the cantilever´s response to water and ethanol vapors are explained by the higher wettability of gold towards ethanol. High values of frequency shifts cannot be justified by the viscosity and density effect of those gases but by the mass and stiffness effects. The negative shifts obtained with liquid ethanol and water is confirmed by the measurements realized in liquids having different viscosities. Correlations between shifts obtained and mass/stiffness effects related to the porous microstructure of PZT thick-film cantilever are proposed.