Analyzing and Organizing Soft Matter with Acoustic Holography

非技术描述声波可以施加足够大的力来悬浮物体并在三维空间中移动它们。声悬浮物体也会影响声场，散射声波并重新定向它们的力。散射波调解对象之间的相互作用，使它们组织成动态的三维组件。这些波-物质复合系统构成了一种基本上未被探索的物质状态，具有非凡的和潜在的有用性质。关于“用声学全息术分析和组织软物质”的计划致力于开发控制声学力所需的基本原理和实用技术，阐明波-物质复合系统的物理学，并提出基于散射声定量分析的材料表征新范式。这个实验项目的动机是主要研究者最近在波-物质相互作用理论方面的突破，该理论解释了如何设计和投射移动物质的声波。从这些研究中产生的原则既具有普遍性，又具有根本性。此外，它们在非接触式制造和3D显示等不同领域都有实际应用。这些应用的技术转让已经在进行中，通过声学全息术进行声学操纵的科学有助于在K-12部门进行有效的STEM推广。它还为本科生提供了丰富的可访问的研究项目，从而有助于建立STEM研究的多样性和包容性的管道。技术描述最近引入的声动力学框架解释了声波的振幅和相位分布如何在受声波作用的物体上产生力和扭矩。一个类似的方法已被证明是非常富有成效的领域的光学显微操作提供设计原则的光学全息图，实现所需的力景观。将光学操纵原理转化为实验实现受益于塑造光波前的高度先进技术。目前还没有这样的技术用于声音。因此，实现声动力学的好处需要一种新的方法来计算全息。该计划通过引入光谱全息术作为计算全息术的新范例来弥合这一技术差距。光谱全息术是一种波前雕刻的方法，其依赖于在少量离散发射器处但在宽频率范围内控制波的振幅和相位。虽然标准的单色全息图创建静态的时间平均力场，但光谱全息图可以在广泛的时间和长度尺度上具有动态内容。沉浸在这种多尺度景观中的单个物体和多体系统的时间依赖行为代表了一个新兴的研究领域。研究这些系统的预期成果包括经典波-物质相互作用基础科学的进展以及软物质和颗粒材料自组织新原理的发现。惯性在声音介导的自组织中的关键作用构成了一个特别有前途的基础发现前沿，如波驱动振荡器的显着动力学行为。该项目还为工业技术转移提供了令人兴奋的机会，包括用于制造的无接触材料运输、用于体积显示的快速3D扫描和大规模远程材料表征。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical DescriptionSound waves can exert forces that are large enough to levitate objects and move them in three dimensions. Acoustically levitated objects also influence the sound field, scattering sound waves and redirecting their forces. Scattered waves mediate interactions among the objects that cause them to organize themselves into dynamic three-dimensional assemblies. These wave-matter composite systems constitute a largely unexplored state of matter with extraordinary and potentially useful properties. The program on “Analyzing and Organizing Soft Matter with Acoustic Holography” is dedicated to developing the fundamental principles and practical techniques needed to control acoustic forces, elucidating the physics of wave-matter composite systems, and advancing a new paradigm for materials characterization based on quantitative analysis of scattered sound. This experimental program is motivated by the Principal Investigator’s recent breakthrough in the theory of wave-matter interactions that explains how to design and project sound waves that move matter. Principles emerging from these studies are both general and fundamental. They have practical applications, moreover, in areas as diverse as non-contact manufacturing and 3D displays. Technology transfer for these applications already is under way, The science of acoustic manipulation through acoustic holography lends itself to effective STEM outreach in the K-12 sector. It also provides a wealth of accessible research projects for undergraduates, thereby helping to build the pipeline for diversity and inclusion in STEM research.Technical DescriptionThe recently-introduced acoustokinetic framework explains how the amplitude and phase profiles of a sound wave give rise to forces and torques on insonated objects. An analogous approach has proved extraordinarily fruitful for the field of optical micromanipulation by providing design principles for optical holograms that implement desired force landscapes. Translating principles of optical manipulation into experimental realizations has benefitted from highly advanced technology for shaping the wavefronts of light. No such technology currently exists for sound. Realizing the benefits of acoustokinetics therefore requires a novel approach to computational holography. This program bridges this technological gap by introducing spectral holography as a new paradigm for computational holography. Spectral holography is an approach to wavefront sculpting that relies on controlling the wave’s amplitude and phase at a small number of discrete emitters but over a wide range of frequencies. Whereas standard monochromatic holograms create static time-averaged force fields, spectral holograms can have dynamic content over a wide range of time and length scales. The time-dependent behavior of individual objects and many-body systems immersed in such multi-scale landscapes represent an emerging area of research. Anticipated outcomes from studying these systems include advances in the fundamental science of classical wave-matter interactions and discovery of new principles of self-organization in soft-matter and granular materials. The critical role of inertia in sound-mediated self-organization constitutes a particularly promising frontier for fundamental discoveries such as the remarkable dynamical behavior of wave-driven oscillators. This program also provides exciting opportunities for technology transfer to industry, including contact-free materials transport for manufacturing, rapid 3D scanning for volumetric displays and large-scale remote materials characterization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.