Ultrasonic wave micro manipulation of micro particle and its application on measurement

当微小颗粒如充有气体的微气泡流入超声波场中时，微颗粒与超声波相互作用，气泡产生聚集，形成大质量的气泡。这些气泡被超声波捕捉到周围的液体流动。本研究提出利用超音波操控微小粒子，并将其应用于高精度量测。本研究的主要结果如下。1)建立了能够模拟超声波场中微小颗粒运动的数值模型，并对微小颗粒的动力学行为进行了数值研究。该数值模型基于流体动力学，能够精确模拟超声波作用下微粒的运动。2)提出了一种基于初级和次级Bjerknes力的微泡捕获技术，并介绍了其在药物释放领域的应用。本实验从理论和实验两方面探讨了超声波捕集微气泡的机理。在超声波频率为5MHz的超声波作用下，采用两种不同类型的微气泡进行实验。利用平均直径为20 μ m和1.3 μ m的两种不同类型的充气微气泡，观察了超声波场中微气泡的动力学行为。3)提出了几种基于声辐射力的小粒子操纵方法，并给出了它们在高精度测量中的应用。这些结果为超声波微粒子操控提供了有价值的知识和方法。

When small particles such as gas filled micro bubbles flow into ultrasonic wave field, the micro particles interact with the ultrasonic waves and the bubbles produce aggregations to make large masses of bubbles. Those bubbles are trapped against the surrounding liquid flow by ultrasonic waves. In this research, the micro particles manipulation by ultrasonic waves are proposed and its application to high accuracy measurement is proposed. Main results of this research are as follows. 1) Numerical model which is able to simulate micro particle motion inside the ultrasonic wave fields is developed and the dynamics of small particles are examined numerically. This numerical model is based on fluid dynamics and is able to simulate precise movement of micro particles under ultrasonic waves. 2) Micro bubble trapping based on primary and secondary Bjerknes forces is proposed and its application in the field of drug delivery system is demonstrated. In this experiment, the mechanism of micro bubbles trapping by ultrasonic waves is discussed both theoretically and experimentally. The experiments are carried out using two different types of micro bubbles for the ultrasonic waves with ultrasonic wave frequency 5 MHz. The dynamics of micro bubbles inside ultrasonic wave field are observed using two different types of gas filled micro bubbles with mean diameter 20 micro meter and with mean diameter 1.3 micro meter. 3) Several small particle manipulation methods based on acoustic radiation forces are proposed and some applications in the field of high accuracy measurement are shown. These results give valuable knowledge and methods of micro particle manipulation by ultrasonic waves.