Thin film flexible/bendable acoustic wave devices: Evolution, hybridization and decoupling of multiple acoustic wave modes

• Published in: Surface & coatings technology 2019-01, Vol.357, p.587-594
• Main Authors: Tao, R., Wang, W.B., Luo, J.T., Ahmad Hasan, S., Torun, H., Canyelles-Pericas, P., Zhou, J., Xuan, W.P., Cooke, M.D., Gibson, D., Wu, Q., Ng, W.P., Luo, J.K., Fu, Y.Q.
• Format: Article
• Language: English
• Subjects: Acoustic waves; Flexible devices ZnO; Lamb wave; Surface acoustic wave; Thin films
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2018.10.042

Based on theoretical analysis, finite element simulation and experimental verifications, we have systematically investigated evolution, hybridization and decoupling of multiple acoustic wave modes and vibration patterns generated from piezoelectric film acoustic wave devices fabricated on flexible thin foils/plates. ZnO piezoelectric films deposited on flexible and bendable Al foil and plates were selected for this particular study. The ZnO/Al acoustic wave devices were chosen with wavelengths varied from 12 to 800 μm, ZnO film thickness from 2 to 10 μm and Al foil/plate thickness from 10 to 600 μm. Multiple acoustic wave modes (including symmetrical and asymmetrical Lamb waves, Rayleigh waves and higher harmonic/Sezawa wave modes) were generated, hybridized occasionally with each other, and then easily decoupled by changing the ratios of the substrate/film thicknesses to wavelengths. Ratios between device wavelength and substrate/film thickness have been identified to be the dominant parameter in determining the evolution and hybridization of multiple wave modes and their vibration patterns, which provide useful design guidance for both sensing and microfluidic applications using these flexible and bendable acoustic wave devices. •Evolution, hybridization and decoupling of multiple acoustic wave modes are investigated using FEA and experimental methods•Symmetrical and asymmetrical Lamb waves, Rayleigh waves and Sezawa waves are generated from thin film acoustic wave devices•Ratios between device wavelength and thickness are identified dominant in evolution and hybridization of wave modes•Design methodology are applicable for sensing and microfluidic applications using flexible/bendable acoustic wave devices