Institute of Sensor and Actuator Technology, Coburg University of Applied Sciences, Coburg, Germany.
Sensors (Basel). 2013 Feb 27;13(3):2777-85. doi: 10.3390/s130302777.
Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid-liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner.
最近，一种基于固液界面表面声波的多模式转换的声波导传感器已经被引入，用于二元和三元混合物的浓度测量、液位感应、空间非均质性研究或气泡检测。在本贡献中，首次通过纹影成像可视化了这种声波导传感器中的声波传播，用于连续和突发操作。在声波导中，通过 1MHz 的单相换能器在 1mm 厚的薄玻璃片上激励反对称零阶兰姆波模式。通过与被研究的液体接触，在第一块板上传播的兰姆波向相邻的液体中发射压力波，这会在第二块板上激励兰姆波，而第二块板又会在液体内部产生向第一块板传播的压力波，如此循环往复。纹影图像证明了这种在声波导内的多次反射，这证实了以前基于接收器信号的考虑和计算。有了这些知识，就可以更好地解释带有声波导传感器的传感器概念。
