Rayleigh and shear-horizontal surface acoustic waves simultaneously generated in inclined ZnO films for acoustofluidic lab-on-a-chip

Pang, H.-F. et al. (2022) Rayleigh and shear-horizontal surface acoustic waves simultaneously generated in inclined ZnO films for acoustofluidic lab-on-a-chip. Surface and Coatings Technology, 442, 128336. (doi: 10.1016/j.surfcoat.2022.128336)

Abstract

There are significant challenges in controlling uniformity of crystal inclination angles, growth orientations and film thicknesses to generate dual-mode surface acoustic waves (e.g., Rayleigh ones and shear-horizontal ones) for lab-on-a-chip applications. In this study, we demonstrate large area (up to three inches) and uniformly inclined piezoelectric ZnO films, sputtering-deposited on silicon using a glancing angle deposition method. Characterization using X-ray diffraction showed that the inclined ZnO films have an average crystal inclination angle of 29.0°, apart from the vertical (0002) orientation, at a substrate tilting angle of 30o. Reflection signals of ZnO/Si surface acoustic wave devices clearly show the generations of both shear horizontal surface acoustic waves and Rayleigh waves. The Rayleigh waves enable efficient acoustofluidic functions including streaming and transportation of sessile droplets. Excitation direction of Rayleigh waves on the acoustofluidics versus the inclined angle direction has apparent influences on the acoustofluidic performance due to the anisotropic microstructures of the inclined films. The same device has been used to demonstrate biosensing of biotin/streptavidin interactions in a liquid environment using the shear-horizontal surface acoustic waves, to demonstrate its potential for integration into a complete lab-on-a-chip device.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Reboud, Professor Julien

Creator Roles

Reboud, J.: Data curation, Validation, Writing – review and editing

• Authors: Pang, H.-F., Tao, R., Luo, J., Zhou, X., Zhou, J., McHale, G., Reboud, J., Torun, H., Gibson, D., Tao, K., Chang, H., and Fu, Y.-Q.
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Journal Name: Surface and Coatings Technology
• Publisher: Elsevier
• ISSN: 0257-8972
• ISSN (Online): 1879-3347
• Published Online: 04 March 2022
• Copyright Holders: Copyright © 2022 Elsevier B.V.
• First Published: First published in Surface and Coatings Technology 442: 128336
• Publisher Policy: Reproduced in accordance with the publisher copyright policy