Mesoporous TiO2 Sensitive Films for Love Wave Humidity Detection: Origins of Stress Release Induced by Sorption
Résumé
Mesoporous titania-coated acoustic humidity sensors show strongly non-linear responses at high exposure, not fully explained by water condensation. Three possible sources of stresses that alter the film mechanical behavior have been considered in this work: increased swelling, unreleased sol-gel stress, and capillary contraction. If the latter is linked to the film porous nature and cannot be avoided, the two other are mainly side effects of the specific fabrication process developed for the deposition of mesoporous oxides on quartz piezoelectric substrates: partial crystallization and a large pore size distribution.