The role of boundaries in 2D active nematics

边界在二维活性向列中的作用

• 批准号: 1810077
• 负责人: Seth Fraden
• 金额: $ 48.27万
• 依托单位: Brandeis University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1810077&HistoricalAwards=false
• 关键词: role; boundaries; 2D; active; nematics

PART 1: NON-TECHNICAL SUMMARY Active matter seeks to describe materials in which chemical energy is consumed at the nanoscale resulting in motion at the macro scale. Examples include the motion of living cells. Recent theories suggest that the motions of living cells are constrained by physical laws to certain characteristic behaviors, and these same theories raise the intriguing possibility that it is possible to engineer new materials with functionalities that heretofore are only found in living organisms. Currently, a lack of quantitative experiments to test theory is hampering progress. This proposal seeks to rectify this imbalance by providing quantitative comparison between theory and experiment in confined two-dimensional active liquid crystals. These tests of theory and discovery of new phenomena will propel the field forward leading to the creation of novel materials, such as self-organizing engines and self-pumping fluids. PART 2: TECHNICAL SUMMARY Active matter research is at the forefront of the field of soft matter, but a lack of quantitative experiments to test theory is hampering progress. This proposal seeks to rectify this imbalance. Experimental studies of confined 2D active nematic liquid crystals will be performed with the goal to elucidate the role of boundary conditions in influencing structure and dynamics. A model system, extensile microtubule bundles, will be employed because of their relative simplicity and high degree of controllability. One thrust will be to establish the microscopic mechanism by which microtubule bundles extend and produce flow. This will be accomplished using combined fluorescence and second harmonic generation microscopy. A second thrust will be to investigate the function of boundary conditions on active nematics by creating a wide variety of confined structures and quantitatively measure the quantities necessary to compare theory and experiment. This will be accomplished using photolithographic and microfluidic manufacturing methods and quantitative light microscopy. A third thrust will be to compare experiment to theory using finite element computation and a fourth thrust will be to engineer soft machines based on confined active nematics that self-organize to perform work, such as pumping of fluids.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.

第一部分： 活性物质试图描述其中化学能在纳米级消耗导致宏观尺度运动的材料。例子包括活细胞的运动。最近的理论表明，活细胞的运动受到物理定律的限制，只能进行某些特定的行为，这些理论提出了一种有趣的可能性，即有可能设计出具有迄今为止仅在生物体中发现的功能的新材料。目前，缺乏定量实验来测试理论阻碍了进展。该建议旨在纠正这种不平衡，通过提供定量的理论和实验之间的比较，在受限的二维有源液晶。这些理论的测试和新现象的发现将推动该领域向前发展，从而创造出新的材料，如自组织发动机和自泵流体。 第二部分： 活性物质研究处于软物质领域的最前沿，但缺乏定量实验来测试理论阻碍了进展。这项建议旨在纠正这种不平衡。实验研究受限的二维有源液晶将进行与目标，以阐明边界条件的作用，影响结构和动力学。一个模型系统，可伸展的微管束，将采用，因为它们的相对简单和高度的可控性。其中一个重点将是建立微管束延伸和产生流动的微观机制。这将使用组合荧光和二次谐波发生显微镜来实现。第二个目标是通过建立各种各样的受限结构来研究边界条件对主动向列学的作用，并定量测量比较理论和实验所需的量。这将使用微流控和微流体制造方法和定量光学显微镜来实现。第三个重点是使用有限元计算将实验与理论进行比较，第四个重点是设计基于受限主动向列的软机器，这些机器可以自组织执行工作，例如泵送流体。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Self-organized dynamics and the transition to turbulence of confined active nematics

• DOI: 10.1073/pnas.1816733116
• 发表时间: 2019-03-12
• 期刊: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• 影响因子: 11.1
• 作者: Opathalage, Achini;Norton, Michael M.;Dogic, Zvonimir
• 通讯作者: Dogic, Zvonimir

Optimal Control of Active Nematics

• DOI: 10.1103/physrevlett.125.178005
• 发表时间: 2020-10-23
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Norton, Michael M.;Grover, Piyush;Fraden, Seth
• 通讯作者: Fraden, Seth