Title: An optimisation of IDTs for surface acoustic wave sensor

Authors: Thu Hang Bui; Tung Bui Duc; Trinh Chu Duc

Addresses: Department of Microelectromachanical Systems and Microsystems, University of Engineering and Technology, VNU, Hanoi, 144 Xuan Thuy, Cau Giay, Hanoi, Vietnam ' Department of Microelectromachanical Systems and Microsystems, University of Engineering and Technology, VNU, Hanoi, 144 Xuan Thuy, Cau Giay, Hanoi, Vietnam ' Department of Microelectromachanical Systems and Microsystems, University of Engineering and Technology, VNU, Hanoi, 144 Xuan Thuy, Cau Giay, Hanoi, Vietnam

Abstract: Acoustic wave devices have been applied for detecting chemical and physical phenomena in gas and liquid applications. For the surface acoustic wave sensors (SAW sensors), the mechanical waves propagating through a piezoelectric crystal include Rayleigh and shear modes. They are influenced by the shape and size of the metal electrodes interdigital transducers (IDTs). Traditionally, IDTs were fabricated in the form of long straight parallel fingers on the piezoelectric substrate. This paper presents a piezoelectric device with focused IDTs (FIDTs) placed on a Y-Z lithium niobate (LiNbO₃) substrate to achieve Rayleigh wave energy convergence. The energy conservation principle, called the Rayleigh principle, is used to prove the effective performance of IDTs with concentric shape. Amplitude fields of the conventional and concentric structures are shown. In addition, the energy loss and the output signal changes are compared between the two cases.

Keywords: SAW sensors; focused IDTs; interdigital transducers; optimisation; surface acoustic wave sensors; piezoelectric crystals; lithium niobate substrate; LiNbO3; energy conservation.

DOI: 10.1504/IJNT.2015.067906

International Journal of Nanotechnology, 2015 Vol.12 No.5/6/7, pp.485 - 495

Published online: 08 Mar 2015 *

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