NH3-Sensing Mechanism Using Surface Acoustic Wave Sensor with AlO(OH) Film

Xiaofeng Xu; Xiaotao Zu; Dongyi Ao; Jingxia Yu; Xia Xiang; Wanfeng Xie; Yongliang Tang; Sean Li; Yongqing Fu

doi:10.3390/nano9121732

NH₃-Sensing Mechanism Using Surface Acoustic Wave Sensor with AlO(OH) Film

Nanomaterials (Basel). 2019 Dec 4;9(12):1732. doi: 10.3390/nano9121732.

Authors

Xiaofeng Xu¹, Xiaotao Zu^{1

2}, Dongyi Ao¹, Jingxia Yu¹, Xia Xiang¹, Wanfeng Xie³, Yongliang Tang⁴, Sean Li⁵, Yongqing Fu⁶

Affiliations

¹ School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, China.
² Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.
³ School of Electronics and Information, Qingdao University, Qingdao 266071, China.
⁴ School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China.
⁵ School of Materials Science and Engineering, The University of New South Wales, 2052 Sydney, Australia.
⁶ Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne NE1 8ST, UK.

Abstract

In this study, AlO(OH) (boehmite) film was deposited onto a surface acoustic wave (SAW) resonator using a combined sol-gel and spin-coating technology, and prepared and used as a sensitive layer for a high-performance ammonia sensor. The prepared AlO(OH) film has a mesoporous structure and a good affinity to NH₃ (ammonia gas) molecules, and thus can selectively adsorb and react with NH₃. When exposed to ammonia gases, the SAW sensor shows an initial positive response of the frequency shift, and then a slight decrease of the frequency responses. The sensing mechanism of the NH₃ sensor is based on the competition between mass-loading and elastic-loading effects. The sensor operated at room temperature shows a positive response of 1540 Hz to 10 ppm NH₃, with excellent sensitivity, selectivity and stability.

Keywords: AlO(OH) film; Ammonia sensor; Surface acoustic wave.

Grants and funding

(U1630126, U1230124)/NSAF Joint Fund