基于声子晶体板调控声场的微纳颗粒操控研究

The development of the theory and method for acoustic manipulation is crucial to the application of ultrasonic manipulation technology. Supported by the NSFC for Youth Science, we developed finite-difference time-domain (FDTD) method to determine the acoustic radiation force on objects in ideal fluids subjected to an acoustic wave, experimentally demonstrated that microparticles (microbubbles, cell) can be aligned, trapped or precisely transported by acoustic standing wave in microchannel and explained the corresponding mechanism. Related results have been published in kinds of journal, such as: JASA, APL, Biomicrofluidics etc., and reported with research highlight on the web of American Institute of Physics. However, the acoustic field in conventional acoustic manipulation device, is usually generated directly by acoustic transducer, can’t be redesigned easily, nor can the corresponding acoustic radiation forces be modulated efficiently. In this project, we will investigate acoustic manipulation particles based on phononic crystal slab (PCS) structures. Since their inception, phononic crystals have been associated mainly with the concept of controlling the propagation and spatial confinement of acoustic waves. Indeed, the enhanced spatial confinement of an acoustic wave means that strong variations of wave intensity can be achieved over a small region of space and therefore can exert a large and controllable acoustic force on particle immersed in the confined field. Firstly, we will theoretically design the PCS suitable for acoustic manipulation; Secondly, the acoustic radiation forces of particle on the PCS will be analyzed and optimized by numerical method; Then, the structure of PCS will be fabricated by MEMS technique; At last, we will experimentally study trapping, sorting, and transporting of microparticles based on PCS field. The results of this project can not only provide high resolution, large range and versatile manipulation methods, but also provide a promising integrated on-chip platform for acoustic manipulation of micromechanical devices.

声操控理论和方法是重要的声学问题，是发展新型声操控应用技术的基础。此前在青年科学基金支持下，申请人及项目组发展了时域有限差分法研究声辐射力，并指导实验揭示了声表面驻波操控微粒定点聚集、排列、移动的物理机制和影响因素。项目的研究成果在JASA，APL，Biomicrofluidics等专业期刊发表论文7篇，声操控的成果也作为研究亮点被美国物理联合会专题报道。目前声操控采用的声场在自由调控和设计优化方法上仍存在不足，是该技术进一步发展和应用的瓶颈。声子晶体具有奇特声子能带，能够调制声波或弹性波的传播，可用于灵活调控声辐射力。本项目拟采用理论方法设计适用于微粒操控的声子晶体板（PCS）结构、数值模拟声辐射力场、并利用MEMS工艺研制PCS器件，研究微粒在PCS器件内的捕获、分类、移动等效应。本研究不仅能获得高精度、宽范围、多形式操控工具，还有望为声操控器件的微型化、集成化提供理论支持和实验依据。

声操控技术作为一种无损、非接触的声波操控微粒手段，在物理、化学和生命科学中发挥着重要作用，为解决目前声操控采用的声场在自由调控和设计优化方法上存在的不足，本项目从理论和实验上研究了多种声子晶体板调控声场的微粒操控。首先研究了含周期栅格的平板A0模式Lamb波局域强场操控微粒，理论预言并实验实现了微粒的捕获、筛选与释放效应；然后研究了含周期孔软板的FP效应局域强场的微粒操控，理论实现对微粒的筛选、自组装等功能；进一步理论研究了含周期栅格的双板组成的狭缝系统的声场特性，并理论发现狭缝可产生强局域声场及可以操控尺寸远小于波长的微粒；此外，还研究了相变铁电材料声子晶体的声场特性，发现通过调控温度可以实现灵活调控声传播和声辐射力的大小与方向；以及体波联合表面波实现多尺度微粒操控。本项目的研究实现了高精度、宽范围、多形式的微粒操控，还为声操控器件的微型化和集成化提供了理论支持和实验依据。