Title

Lgx Pure Shear Horizontal Saw For Liquid Sensor Applications

Keywords

Langasite family of crystals; Sensor for Liquid Applications; Shear Horizontal Acoustic Wave; Surface Transverse Acoustic Wave

Abstract

In this paper we report theoretical and experimental properties of the shear horizontal (SH) mode for the LGX family of crystals, which includes langasite (LGS), langanite (LGN), and langatate (LGT). These crystals are of the trigonal class 32 group, as quartz, and they exhibit the Shear Horizontal (SH) symmetry type uncoupling for the Euler angles [0° θ 90°]. This surface acoustic mode, also know as Surface Transverse Wave (STW) is especially attractive for liquid sensing, because the pure horizontal particle polarization characteristic of this wave, with the material particle motion parallel to the surface, is not as severely damped as observed for the general polarized SAW or pure sagittal Rayleigh waves, which have a significant polarization component normal to the surface. The results reported in this paper focus on one of the materials from the LGX family, LGT. The experimental data uncovers a zero temperature coefficient of delay (TCD) propagation direction around 140°C on the LGT crystal. In addition, liquid loading experiments with both water and photoresist at the surface of SH wave resonators and delay lines along that orientation have been carried out, showing the expected moderate attenuation of the SH mode. The identified propagation direction possesses high coupling, and significant energy trapping close to the surface, yet another attractive characteristic for improving the sensitivity of surface acoustic wave liquid sensors. The measured phase velocity is 2660 m/s, within 0.2% of the calculate value, and 55% below the phase velocity of the 36° Y rotated quartz, thus permitting the fabrication of more compact SH surface acoustic wave sensors and filters.

Publication Date

12-1-2002

Publication Title

Proceedings of IEEE Sensors

Volume

1

Issue

2

Number of Pages

1165-1170

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

Socpus ID

1542301485 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/1542301485

This document is currently not available here.

Share

COinS