Focusing and waveguiding of Lamb waves in micro-fabricated piezoelectric phononic plates

Meng-Jhen Chiou; Yu-Ching Lin; Takahito Ono; Masayoshi Esashi; Sih-Ling Yeh; Tsung-Tsong Wu

doi:10.1016/j.ultras.2014.05.007

Focusing and waveguiding of Lamb waves in micro-fabricated piezoelectric phononic plates

Ultrasonics. 2014 Sep;54(7):1984-90. doi: 10.1016/j.ultras.2014.05.007. Epub 2014 May 24.

Authors

Meng-Jhen Chiou¹, Yu-Ching Lin², Takahito Ono³, Masayoshi Esashi², Sih-Ling Yeh¹, Tsung-Tsong Wu⁴

Affiliations

¹ Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan.
² WPI-AIMR, Tohoku University, Sendai 980-0845, Japan.
³ Department of Mechanical Engineering, Tohoku University, Sendai 980-0845, Japan.
⁴ Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan. Electronic address: wutt@ntu.edu.tw.

PMID: 24909597
DOI: 10.1016/j.ultras.2014.05.007

Abstract

This paper presents results on the numerical and experimental studies of focusing and waveguiding of the lowest anti-symmetric Lamb wave in micro-fabricated piezoelectric phononic plates. The phononic structure was based on an AT-cut quartz plate and consisted of a gradient-index phononic crystal (GRIN PC) lens and a linear phononic plate waveguide. The band structures of the square-latticed AT-cut quartz phononic crystal plates with different filling ratios were analyzed using the finite element method. The design of a GRIN PC plate lens which is attached with a linear phononic plate waveguide is proposed. In designing the waveguide, propagation modes in square-latticed PC plates with different waveguide widths were studied and the results were served for the experimental design. In the micro-fabrication, deep reactive ion etching (Deep-RIE) process with a laboratory-made etcher was utilized to fabricate both the GRIN PC plate lens and the linear phononic waveguide on an 80 μm thick AT-cut quartz plate. Interdigital transducers were fabricated directly on the quartz plate to generate the lowest anti-symmetric Lamb waves. A vibro-meter was used to detect the wave fields and the measured results on the focusing and waveguiding of the piezoelectric GRIN PC lens and waveguide are in good accordance with the numerical predictions. The results of this study may serve as a basis for developing an active micro plate lens and related devices.

Keywords: Focusing; Lamb wave; Phononic crystal; Piezoelectric plate; Waveguiding.