空气中基于声学人工结构的声辐射力特性及其对颗粒的操控研究

The acoustic radiation forces (ARFs) and acoustic manipulations of particles based on acoustic artificial structures have attracted much attention recently. Currently, the related studies are mainly focused on the background of water or liquids analogy to the vivo environments. In these liquid backgrounds, resistance in transportation is very strong, and the manipulations of vivo lives through ARFs is almost impossible, which greatly restrict the extensive applications of ARFs on the manipulations of particles. For the case of air background, there are many advantages such as weak resistance and large acoustic wavelength, which will be beneficial to remote manipulation and transportation of big particles and vivo lives through ARFs. However, the acoustic artificial structures in air behave as rigid, which means that the ARFs based on the intrinsic modes of artificial structures in liquid background cannot accrue in air. In this project, we will explore the rules governing the modulations of acoustic fields by artificial structures in air, investigate ARFs of particles in air induced by the artificial fields, and illustrate the interactions between the ARFs and particle parameters. We will theoretically and experimentally demonstrate the acoustic trapping, pulling, and focusing effects of particles in air by acoustic artificial field. Combined with these studies, we will design new ARF based acoustic devices such as acoustic levitation and acoustic torque. This project will be help to discover new phenomena, to bring out new concepts and to anticipate new applications, which is of scientific significance and is valuable for practical applications.

基于声学人工结构的声辐射力及其对微粒的操控研究近年来引起了国内外学者的广泛关注，现阶段研究大多以水或模拟生命体环境的流体为基体，这些流体基传输阻力大，并且在活体操控方面具有很大的局限性，这极大地限制了声辐射力在微粒操控方面的应用。对于空气基体，声波长较长，声辐射力传输阻力小，故其在远距离操控和运输大颗粒以及活体生物方面具有得天独厚的优势；但是，在空气中声学人工结构基本上可以视为刚性，因此以往研究中基于人工结构内禀振动模式的声辐射力规律不再适用。本课题探索空气中声学人工结构对声场的调控规律以及颗粒在人工声场中所受的声辐射力性质，探讨空气中颗粒所受声辐射力与微粒性质的关系，理论上研究并在实验上实现空气中颗粒在声场中的聚集、吸引、捕获等效应，并将这些新效应同应用结合，设计不同于传统基于超声换能器的新型声悬浮和声力矩等装置。这些研究将带来新现象、新规律和新应用，具有科学意义和应用价值。

本项目中我们致力于空气中声学人工结构对于微粒的调控研究。具体地，我们研究了空气中一维声学周期结构板对于微粒的吸附力研究。研究表明，一维声学结构板会在低频部分具有Pabry-Perot共振和Bragg衍射两类共振，这两种声学共振会对微粒的吸附力不同。我们也研究了由点缺陷和波导组成的复合结构对于声波/弹性波的模式转化和单向传输特性。我们的研究表明，由于波导模式和共振腔模式的对称性匹配，在入射声波导中的声偶模式通过此装置后会转换为出射波导中的声奇模式，这种单向转换进一步导致系统的声波/弹性波单向传输特性，在声集成二级管的设计和应用中有巨大的前景。通过在声硬固体板表面雕刻二维周期性孔洞结构，我们现实了对硬固体板中表面波的调制。通过在周期性二维结构中引入线缺陷，可以让声表面波在固体结构板中高效地转弯和分束。最后，我们相信，我们在项目中取得的这些研究结果将会进一步开发声子晶体、声固体结构板的新特性，为利用声子晶体、声固体结构板设计各种微粒操控声学器件提供一些有益的指导。