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

非技术摘要：科学家们早就知道，人们可以通过在微观尺度上对材料进行图形化来显著改变材料的性质。然而，这样做带来了一个重大挑战：这种模式必须在微观尺度上进行，而且要跨越很远的距离，这阻碍了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调节的相互作用产生复杂的结构。用人造材料做类似的事情需要更好地理解自组织过程，以及在微观粒子之间进行工程力的实用方法。这个项目探索了一种被称为“光结合”的效应，它利用光在粒子簇之间产生复杂的力。研究小组正在开发新的实验和数值工具，以探索利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”的原理验证研究，这是一种使用声音代替光的类似效果。这两项工作的长期目标都是利用这些新工具来更好地理解一般的自组织，以及为工业、国防和消费者应用提供新一代的人造材料。该项目还包括通过综合教育和研究机会，在中学到研究生阶段增加代表性不足群体在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，为初高中学生开发一门新的实验物理课程；本课程不依赖于“固定的”物理实验，而是向学生展示科学实验的完整生命周期，从设计到执行和数据分析。技术摘要：理解自组织是许多科学领域感兴趣的问题，包括生物学、化学、物理学和工程学。胶体系统已经成为研究这种现象的一个有用的实验平台，因为存在各种技术来改变胶体颗粒之间的力。尽管如此，可以产生的力的类型是有限的：它们通常是短程的，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结合的效应，它利用光来诱导多粒子相互作用，这种相互作用是远距离的，定向的，成对的非保守的，并且可以实时改变。此外，该项目还包括声学结合的原理验证研究，声学结合在非热和惯性状态下产生类似的力。研究小组正在使用新颖的数值和实验方法来详细研究这两种力，并探索这些力如何改变多粒子系统的自组织。这为了解自组织的壮举是如何在自然界中进行的，以及如何利用它们来创造具有复杂微观结构的新型人造材料提供了见解。除了研究目标之外，该项目还包括综合推广工作，通过为学生和他们的老师提供研究机会和暑期项目，增加中学到研究生阶段代表性不足群体对STEM的参与。该奖项反映了美国国家科学基金会的法定使命，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 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.