Mass effects of quartz resonant sensors with different surfacemicrostructures in liquids

摘要

Liquid trapped by the rough surface of a quartz resonatornvibrating in thickness-shear mode (TSM) will act as a mass effect to thencrystal. It has been proven that this mass effect not only depends onnthe liquid mass enclosed in the surface cavities, but also the liquidnproperties and the crystal surface features. Based on a series ofnexperiments, this paper introduces “trapping factor” tonanalyze the mechanism of the liquid mass effect. Influences of differentnsurface microstructures, including structure dimension and orientation,non the liquid mass effect have been studied on 10 MHz fundamental modenAT-cut resonators. The result indicates that the trapping factor of anchess-board structure has no advantage compared to a line-structure. Fornthe same structure height of 0.4 Μm, the mass effect of a crystalnwith about 3 Μm distance line-structure is bigger than that of a 7.5nΜm distance line-structure. With a similar surface roughness value (Rna), the crystal with a line structured surface has a muchnbigger mass effect than that with a randomly rough surface