Study of multi-functional surface acoustic wave sensor using Langmuir-Blodgett (LB) method

介绍了一种用于环境测量的声表面波传感器及其系统。声表面波器件已被广泛用作测量环境的化学和物理传感器。通常，用作传感器的大多数SAW器件涂覆有能够通过物理和化学吸收与感兴趣的化学品相互作用的薄膜。传感器的灵敏度、响应时间和再现性与传感膜的特性密切相关。因此，选择性涂层膜对于SAW传感器的稳定性和再现性是非常重要的。有许多方法来涂覆选择性膜，如空气刷，浸铸，和旋涂的SAW器件具有良好的重现性。超薄有机薄膜目前在集成光学、传感器和纳米技术等许多领域都引起了人们的兴趣。超薄薄膜 ...更多信息 用自组装（SA）法和LB法制备了分子筛。在128 Y切X传播LiNbO_3基片上制作了声表面波延迟线，并在传播路径上涂上了选择性聚合物。聚苯乙烯磺酸钠用作SA膜材料，磷脂酰乙醇胺用作LB膜材料。由于分子的吸附，这些选择性膜的密度、介电常数和电导率发生变化。实验结果表明，声表面波速度的变化与有机气体的浓度成正比。通过使用薄的单层膜获得快速和完全可逆的响应。此外，还利用反射延迟线设计了一种新型的功能传感器。在36 YX的LiTaO_3衬底上制作了反射式SH-SAW延迟线，并采用直角（90 °）边沿反射SAW。在同一衬底上制作了六通道反射延迟线。每个通道具有不同的长度，并且在时域中获得响应。测量了每个延迟线上反射声表面波的相位和幅度作为传感器的响应，并进行了几个实验来验证边缘反射传感器的性能。通过测量SH-SAW垂直入射角反射波的振幅和相位，得到了反射式SAW传感器的基本特性。实验结果表明，反射式SH SAW传感器对气、液相的传感是非常有效的，并提出了无线系统的建议，以保证反射式SH SAW传感器的有效工作。提出了用于精确测量来自多通道传感器的反射波的相位特性的电子测量系统。特别是，它表明，无线传感系统是非常适合于遥感。最后介绍了无线SH-SAW传感器在测量液体样品电导率和粘度方面的应用。少

A surface acoustic wave(SAW) sensor and its system for measuring the environment are presented. SAW devices have been widely used as a chemical and physical sensor for measuring the environment. In general most of the SAW device using as the sensor is coated with a thin film that capable of interaction with the chemical of interest through physical and chemical absorption. Sensitivity, response time, and reproducibility of the sensor are closely related with the characteristics of the sensing film. Therefore, the selective coating film is very important for a stability and reproducibility of the SAW sensor. There are numerous methods to coat a selective film, such as air brushing, dip cast, and spin coating of the SAW devices with good reproducibility.In this paper, first the SAW sensor incorporating an ultra thin selective film is presented. Ultra thin organic films are currently gaining interest in many areas such as integrated optics, sensors, and nano technology. The ultra thin fil … More ms were made by both self-assembled(SA) method and by Langmuir-Blodgett(LB) method. SAW delay lines were fabricated on a 128 Y cut X propagating LiNbO3 substrate and the propagation path was coated with the selective polymer deposited by these transfer technique. The polystyrene sulfonic acid sodium was used as an SA film material and the phosphatidylethanolamine was used as a LB film material. Due to sorption of molecules, the density, permittivity and electrical conductivity of these selective film change. The effects caused to reduce the velocity of the SAW Experimental results showed that the SAW velocity change was quite linear in proportion to the concentration on organic gases. Rapid and totally reversible responses were obtained by using the thin monolayer film. Moreover, it is shown that the thin film is suitable to obtain good linearity, high sensitivity and rapid response.Moreover, a new functional sensor also has been designed by using reflecting delay line. A reflecting SH-SAW delay line was constructed on a 36 YX LiTaO_3 substrate and the right angle(90-degree) edge has been used to reflect the SAW. Six-channel reflecting delay lines have been fabricated on one substrate. Each channel has a different length and the responses are obtained in time domain. Both the phase and amplitude of the reflected SAW on the each delay line were measured as a sensor response.Several experiments were performed to verify the performances of the edge reflection sensor. The basic characteristics of the reflecting SAW sensor were obtained by measuring the amplitude and phase of reflected wave when the SH-SAW is incident to a perpendicular corner. The obtained results showed that the reflecting SH-SAW sensor was very effective for sensing the gas and liquid phase.Wireless systems are also suggested for the effective operation of the reflecting SH-SAW sensor. The electronic measurement system for accurately measuring the phase characteristics of a reflected wave from the multi-channel sensor is proposed. In particular, it is shown that the wireless sensing system is very suitable for remote sensing. Finally it will be shown some applications of the wireless SH-SAW sensors on the measurement of the conductivity and viscosity of sample liquids. Less