title: Development of a Wireless and Passive SAW-Based Chemical Sensor for Organophosphorous Compound Detection.
abstract: A new wireless and passive surface acoustic wave (SAW)-based chemical sensor for organophosphorous compound (OC) detection is presented. A 434 MHz reflective delay line configuration composed by single phase unidirectional transducers (SPUDTs) and three shorted reflectors was fabricated on YZ LiNbO₃ piezoelectric substrate as the sensor element. A thin fluoroalcoholpolysiloxane (SXFA) film acted as the sensitive interface deposited onto the SAW propagation path between the second and last reflectors of the SAW device. The first reflector was used for the temperature compensation utilizing the difference method. The adsorption between the SXFA and OC molecules modulates the SAW propagation, especially for the time delay of the SAW, hence, the phase shifts of the reflection peaks from the corresponding reflectors can be used to characterize the target OC. Prior to the sensor fabrication, the coupling of modes (COM) and perturbation theory were utilized to predict the SAW device performance and the gas adsorption. Referring to a frequency-modulated continuous wave (FMCW)-based reader unit, the developed SAW chemical sensor was wirelessly characterized in gas exposure experiments for dimethylmethylphosphonate (DMMP) detection. Sensor performance parameters such as phase sensitivity, repeatability, linearity, and temperature compensation were evaluated experimentally.
authors.affiliation: Zhejiang University of Media and Communications, Hangzhou 310018, China. xufangqian2006@163.com.
authors.forename: Fang-Qian
authors.initials: FQ
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, No.21, North 4th Ring West Road, Beijing 100190, China. wangwenwq@mail.ioa.ac.cn.
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, No.21, North 4th Ring West Road, Beijing 100190, China. xuexufeng@mail.ioa.ac.cn.
authors.forename: Xu-Feng
authors.initials: XF
authors.lastname: Xue
authors.affiliation: State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, No.21, North 4th Ring West Road, Beijing 100190, China. huhaoliang11@mails.ucas.ac.cn.
authors.forename: Hao-Liang
authors.initials: HL
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, No.21, North 4th Ring West Road, Beijing 100190, China. liuxinlu1987@foxmail.com.
authors.forename: Xin-Lu
authors.initials: XL
authors.lastname: Liu
authors.affiliation: State Key Laboratory of NBC Protection for Civilian, Yangfang, Changping District, Beijing 102205, China. panyong71@sina.com.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Pan
keywords: chemical sensor; fluoroalcoholpolysiloxane (SXFA); organophosphorous compounds; surface acoustic wave (SAW); wireless and passive