ISS: Collaborative Research: Individual and Collective Behavior of Active Colloids in Microgravity

ISS：合作研究：微重力下活性胶体的个体和集体行为

• 批准号: 2126451
• 负责人: Jarrod Schiffbauer
• 金额: $ 4.98万
• 依托单位: Colorado Mesa University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2126451&HistoricalAwards=false
• 关键词: ISS; Collaborative; Research; Individual; Collective

This NSF-CASIS project involves microgravity experiments on the International Space Station (ISS), complementary terrestrial experiments and theoretical/numerical modeling to improve understanding of active colloid transport. Active colloids move by extracting energy from their surroundings and transforming it into mechanical work. These materials have similarities with biological matter, especially for concentrated suspensions where particle-particle interactions yield collective behaviors similar to those found in nature such as swarming flocks of birds, schools of fish and bacterial colonies. Although most theoretical models pertain to an isolated particle traveling in the bulk, the weight of active colloids on Earth causes them to settle at the bottom of the experimental chamber where they translate parallel to the surface. Long term microgravity conditions on the ISS offer a unique opportunity to mitigate buoyancy and sedimentation and obtain bulk measurements that can be compared with theoretical models and elucidate the role of particle-wall interactions, which complicate terrestrial experiments. The results of this project may transform a variety of applications in biomedicine and applications at the Food-Water-Energy Nexus including colloidal assembly and bubble/droplet transport. The project is a collaboration between Colorado Mesa University (CMU) - a Primary Undergraduate Institution with a diverse student body – and Florida International University (FIU) - a research intensive Minority Serving Institution (MSI). It offers a unique opportunity to promote diversity through exposure of undergraduate students to timely research and industry collaboration with the implementation partner Space Tango. The research team will develop a module for FIU’s “Engineers on Wheels” program, which visits local schools, and will collaborate with the Eureka Science Museum and Maverick Innovation Center in Colorado.This NSF-CASIS project will provide a comprehensive understanding of complex physical mechanisms controlling the mobility of individual active colloids and their collective behavior with two distinct goals: (1) optimizing active colloid transport, and (2) understanding effects of microgravity on collective dynamics and non-equilibrium interactions of active matter. The absence of buoyancy in microgravity is expected to resolve a conundrum in terrestrial experiments wherein theoretical models of these systems are derived for isolated particles in the bulk while experimental measurements are almost always made near a wall owing to gravity-induced sedimentation. Proximity to a wall and the accompanying particle-wall interactions (hydrodynamic, phoretic, electrostatic etc.) are often invoked as corrections to explain discrepancies between theory and experiment. However, the precise roles of particle-wall interactions cannot be isolated without comparable measurements far from the wall. Sustained microgravity conditions will enable measurement of particle mobility in the bulk, providing an experimental reference for theoretical models and insight into competing buoyancy effects and wall-particle interactions. Comparison of particle-particle interactions on Earth and on the ISS will also elucidate effects of microgravity on collective behavior in active matter and dense colloidal systems including 3D phase separation. Microgravity experiments will be complemented with terrestrial bulk measurements using optical tweezers as an external forcing mechanism, which will provide insight into other active colloid transport mechanisms (e.g., catalytic) and the applicability of such external forcing for future fundamental studies. The collaboration between FIU and CMU and the partnership with Space Tango offers a unique opportunity to engage students. Undergraduate students will participate ithrough capstone projects at FIU, while CMU students will travel to FIU and gain exposure to a research intensive institution.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.

这一NSF-CASIS项目涉及国际空间站(ISS)的微重力实验、互补的地面实验和理论/数值模拟，以提高对活性胶体运输的理解。活性胶体通过从周围环境中提取能量并将其转化为机械功来运动。这些材料与生物物质有相似之处，特别是在浓缩悬浮液中，颗粒-颗粒相互作用产生的集体行为类似于自然界中发现的行为，如成群结队的鸟类、成群的鱼类和细菌群体。尽管大多数理论模型都是关于孤立的粒子在整体中移动，但地球上活性胶体的重量使它们沉在实验室的底部，在那里它们平行于表面平移。国际空间站上长期的微重力条件提供了一个独特的机会，可以减轻浮力和沉积，获得可以与理论模型进行比较的大量测量数据，并阐明粒子与壁面相互作用的作用，这使地面实验变得复杂。该项目的结果可能改变生物医学中的各种应用和食品-水-能源联系的应用，包括胶体组装和气泡/液滴运输。该项目是科罗拉多梅萨大学(CMU)和佛罗里达国际大学(FIU)的合作项目，CMU是一所拥有多元化学生群体的小学本科生机构，FIU是一家研究密集型少数族裔服务机构(MSI)。它提供了一个独特的机会，通过让本科生接触及时的研究和与实施合作伙伴Space Tango的行业合作来促进多样性。该研究团队将为FIU的“车轮上的工程师”项目开发一个模块，该模块将访问当地的学校，并将与科罗拉多州的尤里卡科学博物馆和小牛创新中心合作。这个NSF-CASIS项目将提供对控制单个活性胶体及其集体行为的复杂物理机制的全面了解，并有两个不同的目标：(1)优化活性胶体运输，(2)了解微重力对集体动力学和活性物质非平衡相互作用的影响。微重力中没有浮力有望解决陆地实验中的一个难题，在这些实验中，这些系统的理论模型是针对整体中的孤立粒子推导出来的，而实验测量几乎总是在墙附近进行，因为重力诱导的沉积。靠近墙面和伴随的颗粒-壁面相互作用(流体、磷酸盐、静电等)经常被引用为更正，以解释理论和实验之间的差异。然而，如果没有远离壁面的类似测量，就不能分离出颗粒与壁面相互作用的确切作用。持续的微重力条件将使测量散体中的颗粒迁移率成为可能，为理论模型提供实验参考，并深入了解竞争浮力效应和壁面-颗粒相互作用。对地球上和国际空间站上的粒子-粒子相互作用的比较还将阐明微重力对活性物质和致密胶体系统中集体行为的影响，包括3D相分离。微重力实验将与使用光学镊子作为外部强迫机制的陆地体积测量相补充，这将深入了解其他活跃的胶体运输机制(例如，催化)以及这种外部强迫对未来基础研究的适用性。FIU和CMU之间的合作以及与Space Tango的合作为吸引学生提供了一个独特的机会。本科生将参加FIU的顶峰项目，而CMU的学生将前往FIU并接触到研究密集型研究所。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。