Load impedance of immersed layers on the quartz crystal microbalance: a comparison with colloidal suspensions of spheres
| Autor: | Meléndez, M., Vázquez-Quesada, A., Delgado-Buscalioni, R. |
|---|---|
| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Langmuir 2020, 36, 31, 9225-9234 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1021/acs.langmuir.0c01429 |
| Popis: | The analytical theories derived here for the acoustic load impedance measured by a quartz crystal microbalance (QCM), due to the presence of layers of different types (rigid, elastic and viscous) immersed in a fluid, display generic properties, such as "vanishing mass" and positive frequency shifts, which have been observed in QCM experiments with soft-matter systems. These phenomena seem to contradict the well-known Sauerbrey relation at the heart of many QCM measurements, but here we show that they arise as a natural consequence of hydrodynamics. We compare our one-dimensional immersed plate theory with three-dimensional simulations of rigid and flexible sub-micron-sized suspended spheres, and with experimental results for adsorbed micron-sized colloids which yield a "negative acoustic mass". The parallel behaviour unveiled indicates that the QCM response is highly sensitive to hydrodynamics, even for adsorbed colloids. Our conclusions call for a revision of existing theories based on adhesion forces and elastic stiffness at contact, which should in most cases include hydrodynamics. Comment: 22 pages, 7 figures |
| Databáze: | arXiv |
| Externí odkaz: |
|