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Observation of Acoustic Streaming in Air and Application to Micro-Manipulator

空气中声流的观测及其在微操作器中的应用

基本信息

批准号：
11650341
负责人：
HASHIMOTO Ken-ya
金额：
$ 0.58万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

It is known that irradiation of powerful ultrasonic waves to liquid causes its flow toward the direction of wave propagation. This phenomenon is called the acoustic streaming. The authors reported that this phenomenon can be enhanced considerably by the use of high frequency ultrasonic waves. Final goal of this project was to observe the acoustic streaming in air. For this purpose, we have devoted ourselves to the development of high frequency and highly efficient ultrasonic transducers for air. First, sol-gel deposition of piezoelectric PZT films was investigated in detail for the application to the ultrasonic transducers. It was shown how the film quality and piezoelectricity are influenced by the temperature profile and environmental gas during the thermal process. Then, the fabrication process for the ultrasonic transducer was investigated. We developed a method to pattern PZT precursor gel prior to the thermal process. In addition, we also developed a technique to fabricate relatively thick and flat PZT structures of arbitrary shape. This technique is advantageous due to its simplicity and high reproducibility. These methods were implemented into the realization of high frequency ultrasonic transducers. The ultrasonic transducer of 1 μm thickness and 160 μm diameter was fabricated. The transducer operates at 2 GHz, and estimated electromechanical coupling was attained to 20%. For the efficient excitation of ultrasonic waves to air, the transducer must be thinned to excite fracture vibration. Presently, we are developing this thinning process. We hope that we will establish this process very soon, and then will try to observe the acoustic streaming in air.

众所周知，强大的超声波照射到液体会导致液体向波传播的方向流动。这种现象称为声流。作者报告说，使用高频超声波可以大大增强这种现象。该项目的最终目标是观察空气中的声流。为此，我们致力于高频高效空气超声波换能器的开发。首先，详细研究了压电 PZT 薄膜的溶胶-凝胶沉积在超声换能器中的应用。展示了热处理过程中温度分布和环境气体如何影响薄膜质量和压电性。然后，研究了超声波换能器的制造工艺。我们开发了一种在热处理之前对 PZT 前驱体凝胶进行图案化的方法。此外，我们还开发了一种制造相对厚且平坦的任意形状的PZT结构的技术。该技术由于其简单性和高再现性而具有优势。这些方法被应用于高频超声换能器的实现中。制作了厚度为1μm、直径为160μm的超声波换能器。该传感器的工作频率为 2 GHz，预计机电耦合达到 20%。为了有效地向空气激发超声波，必须使换能器变薄以激发断裂振动。目前，我们正在开发这种细化工艺。我们希望尽快建立这个过程，然后尝试观察空气中的声流。