Ultrahigh-Frequency Surface Acoustic Wave Sensors with Giant Mass-Loading Effects on Electrodes

Chen, Zhe, Zhou, Jian, Tang, Hao, Liu, Yi, Shen, Yiping, Yin, Xiaobo, Zheng, Jiangpo, Zhang, Hongshuai, Wu, Jianhui, Shi, Xianglong, Chen, Yiqin, Fu, Richard and Duan, Huigao (2020) Ultrahigh-Frequency Surface Acoustic Wave Sensors with Giant Mass-Loading Effects on Electrodes. ACS Sensors, 5 (6). pp. 1657-1664. ISSN 2379-3694

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Official URL: https://doi.org/10.1021/acssensors.0c00259

Abstract

Surface acoustic wave (SAW) devices are widely used for physical, chemical and biological sensing applications, and their sensing mechanisms are generally based on frequency changes due to mass loading effect at the acoustic wave propagation area between two interdigitated transducers (IDTs). In this paper, a new sensing mechanism has been proposed based on significantly enhanced mass-loading effect generated directly on Au IDT electrodes, which enables significantly enhanced sensitivity compared with that of the conventional SAW devices. The fabricated ultrahigh frequency SAW devices show sig-nificant mass-loading effect on the electrodes. With Au electrode thickness increased from 12 nm to 25 nm, Rayleigh mode resonant frequency decreases from 7.77 GHz to 5.93 GHz, while that of the higher longitudinal leaky SAW decreases from 11.87 GHz to 9.83 GHz. The corresponding mass sensitivity of 7309 MHz∙mm2∙g-1 (Rayleigh mode) is ~8.9×1011 times larger than that of a conventional quartz crystal balance (with a frequency of 5 MHz) and ~1000 times higher than that of conventional SAW devices (with a frequency of 978 MHz). Trinitrotoluene concentration as low as 4.4×10-9 M (mol∙L-1) can be detected using the fabricated SAW sensor, proving its giant mass-loading effect and ultrahigh sensitivity.

Item Type: Article
Uncontrolled Keywords: ultrahigh frequency, surface acoustic wave, IDT, mass-loading effect, sensors
Subjects: F200 Materials Science
H600 Electronic and Electrical Engineering
H900 Others in Engineering
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Rachel Branson
Date Deposited: 26 May 2020 13:20
Last Modified: 14 Sep 2020 15:45
URI: http://nrl.northumbria.ac.uk/id/eprint/43250

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