CAREER: Self-Organization of Micro-Particles with Light and Sound

非技术摘要：科学家早就知道，人们可以通过在微观尺度上制作图案来戏剧性地改变材料的性质。然而，这样做带来了一个重大挑战：这种图案化必须在微观范围内进行，但必须远距离进行，从而阻止3D打印等直接技术的使用。还有一种选择：生物有机体能够利用基本化学成分的自组织和可调相互作用来产生复杂的结构。用人造材料做类似的事情，需要更好地理解自组织过程，以及微观粒子之间工程力的实用方法。这个项目探索了一种被称为“光学结合”的效应，它利用光在粒子团之间产生复杂的作用力。研究小组正在开发新的实验和数值工具，以探索使用这种力可以产生的主动和被动结构的范围。此外，研究人员正在进行“声结合”的原理证明研究，这是一种类似的效果，使用声音而不是光。这两项努力的长期目标都是利用这些新的工具来更好地了解总体上的自组织，以及使新一代人造材料能够用于工业、国防和消费应用。该项目还包括努力通过综合教育和研究机会，在中学到研究生阶段增加未被充分代表的群体在STEM领域的参与。特别是，研究人员正在与加州大学默塞德分校的山猫夏季STEM学院合作，为初中和高中学生开发一门新的实验物理课程；这门课程不是依赖“罐头”物理实验，而是让学生接触到科学实验的整个生命周期，从设计到执行再到数据分析。技术摘要：了解自组织对许多科学领域都很感兴趣，包括生物、化学、物理和工程。胶体系统已经成为研究这一现象的一个有用的实验平台，因为有各种技术可以改变胶体颗粒之间的作用力。尽管如此，可以产生的力的类型是有限制的：它们通常是短距离的，只能在合成阶段进行修改。这个项目正在研究一种被称为光学结合的效应，它使用光来诱导多粒子相互作用，这种相互作用是远程的、定向的、成对的、非保守的，并且可以实时改变。此外，该项目还包括对声结合的原理验证研究，这种结合在非热和惯性状态下会产生类似的力。研究小组正在使用新的数值和实验方法详细研究这两种力，并探索这些力如何改变多粒子系统的自组织。这为自然界如何实现自组织的壮举，以及如何利用它们来创造具有复杂微结构的新人造材料提供了洞察力。除了其研究目标，该项目还包括综合外展努力，通过学生及其教师的研究机会和暑期计划，通过研究生水平增加未被充分代表的群体在STEM中的参与。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Abstract:Scientists have long known that one can dramatically alter the properties of a material by patterning it on a microscopic scale. Doing so, however, presents a major challenge: this patterning must happen at a microscopic scale but over large distances, preventing the use of direct techniques like 3D printing. There is an alternative: biological organisms are able to produce complex structure using the self-organization of basic chemical components with tuned interactions. Doing something similar with manmade materials requires a better understanding of the self-organization process, as well as practical methods for engineering forces among microscopic particles. This project explores an effect known as "optical binding", which induces complex forces between clusters of particles using light. The research team is developing new experimental and numerical tools to explore the range of active and passive structures that can be generated using this force. In addition, the researchers are conducting proof of principle research on "acoustic binding", a similar effect which uses sound instead of light. The long term aim of both efforts is to exploit these novel tools to better understand self-organization in general, as well as to enable a new generation of manmade materials for industrial, defense, and consumer applications. The project also includes efforts to increase participation of underrepresented groups in STEM fields at the middle school through graduate level through integrated education and research opportunities. In particular, the researchers are developing a new course on experimental physics for Middle and High school students in collaboration with the Bobcat Summer STEM Academy at UC Merced; rather than relying on ‘canned’ physics experiments, this course exposes students to the complete lifecycle of a scientific experiment, from design through execution and data analysis.Technical Abstract:Understanding self-organization is of interest for many fields of science, including biology, chemistry, physics, and engineering. Colloidal systems have emerged as a useful experimental platform to study this phenomenon, as various techniques exist to modify the forces between colloidal particles. Despite this, there are limits to the type of forces than can be produced: they are typically short range and can only be modified during the synthesis stage. This project is studying an effect known as optical binding, which uses light to induce multi-particle interactions which are long range, directional, pairwise non-conservative, and can be altered in real time. Additionally, the project includes proof-of-principle research on acoustic binding, which produces similar forces in an athermal and inertial regime. The research team is using novel numerical and experimental methods to study both types of force in detail and exploring how these forces modify the self-organization of many-particle systems. This provides insights into how feats of self-organization are performed in the natural world, and how they could be exploited to create new manmade materials with complex microstructure. In addition to its research aims, this project also includes integrated outreach efforts to increase participation of underrepresented groups in STEM at the middle school through graduate level through research opportunities and summer programs for students and their teachers.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.