CAREER: Helical propulsion for tunneling through porous membranes

为了使微型和纳米级机器人设备发挥其功能，它们必须能够在复杂的空间环境中导航。这些小机器会遇到引力和热力，这些力在非常小的长度尺度上可能很重要。因此，它们的运动要么局限于二维空间，要么完全随机化，这将限制它们的功能。该奖项将通过实验研究一种特殊粒子的运动，这种粒子能够作为模型机器人装置进行自我推进。对这些粒子的研究将揭示可用于使它们通过多孔基质进行空间导航的原理。该项目将从寻找最佳粒子形状和表面特征开始，以指导粒子在外部交流电场中的运动。由此产生的粒子将执行预先编程的运动，模仿天然活性生物物质（如精子、微生物和运动蛋白）的轨迹。粒子轨迹与它们穿越多孔膜的能力之间的相关性将被确定，结果将形成设计自主粒子的基础，以增强通过结构化环境（如细胞外基质和多孔岩石）的运输。将通过为研究生和本科生开展教育工作以及为视障儿童开展外展活动来加强这项研究。该研究将通过选修课程“胶体与界面工程”的新章节纳入化学工程课程。CAREER奖将为巴吞鲁日社区学院的本科生提供研究机会，并为路易斯安那州视障学生学校的视障学生提供拓展活动。该奖项旨在回答粒子输运中的一个基本问题：粒子的运动对其在多孔介质中的空间导航能力有什么影响？该项目将通过研究金属贴片微球的运动来解决这个问题，这些微球是通过交流电场驱动的感应电荷电泳在水介质中自我推进的。该项目旨在(1)了解活性胶体的结构-运动学关系，阐明粒子和斑块对称对胶体轨迹的作用；(2)建立引导胶体定向推进的基础，识别粒子空间取向与其轨迹的关系；(3)通过理解粒子轨迹与其通过多孔膜的隧道效率之间的关系，提出增强空间导航的新原理。该奖项将展示在交流电场中引导主动粒子运动学的新方法，并将应用这些知识来导航复杂的结构环境。利用非线性粒子轨迹进行有效空间导航的原理可能并不局限于胶体输运；它们还可以解决各种各样的问题，比如行人在人群中穿行。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。

In order for micro- and nano-scale robotic devices to carry out their functions, they will have to be able to navigate complex spatial environments. These little machines will encounter gravitational and thermal forces that can be significant at very small length scales. As a result, their motion can be either confined to two dimensions or completely randomized, which will limit their functions. This CAREER award will study experimentally the motion of a specialized particle that is capable of self propulsion as a model robotic device. The studies of these particles will reveal principles that can be used to enable their spatial navigation through porous matrices. The project will start by finding the optimal particle shape and surface characteristics to direct the motion of the particles in an external alternating current electric field. The resulting particles will perform preprogrammed motions that mimick the trajectories of natural active biological matter such as spermatozoid, microorganisms and motor proteins. The correlation between the particle trajectories and their ability to tunnel across porous membranes will be determined, and the results will form the basis for designing autonomous particles to enhance transport through structured environments, such as extracellular matrices and porous rocks. The research will be enhanced by complementing it with educational efforts for graduate and undergraduate students and outreach activities for visually impaired children. The research will be incorporated into chemical engineering curricula through a new section in an elective course entitled "Colloids and Interfacial Engineering". The CAREER award will provide research opportunities for undergraduate students at Baton Rouge Community College and outreach activities for visually impaired students at the Louisiana School for the Visually Impaired.This CAREER award seeks to answer a fundamental question in particle transport: What is the effect of a particle's motion on its ability to navigate spatially through porous media? The project will address the question by examining the motion of metal patched microspheres that are self-propelled in aqueous media by AC-electric-field-driven induced charge electrophoresis. The project aims to (1) Develop an understanding of the structure-kinematic relationship for active colloids and elucidate the roles of particle and patch symmetry on colloid trajectories; (2) Establish the basis for guiding the directional propulsion of colloids and identify the relation between the particle's spatial orientations and its trajectories; and (3) Develop new principles for enhanced spatial navigation by understanding the relation between particle trajectory and its tunneling efficiency through porous membranes. The award will present new methods of guiding active particle kinematics in an AC electric field and will apply this knowledge to navigate complex structured environments. The principles of efficient spatial navigation using nonlinear particle trajectories may not be limited to colloidal transport; they may also to diverse problems, such as pedestrians navigating through crowds.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.