CAREER: Helical propulsion for tunneling through porous membranes

为了让微型和纳米级的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。这些小型机器将遇到重力和热力，这些力在非常小的长度尺度上可能会很大。因此，它们的运动可以被限制在两个维度，也可以完全随机，这将限制它们的功能。这一职业奖将从实验上研究一种能够自我推进的特殊粒子的运动，作为机器人设备的模型。对这些粒子的研究将揭示可以用来使它们在多孔基质中进行空间导航的原理。该项目将首先找到最佳的颗粒形状和表面特征，以指导颗粒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，模仿自然活性生物物质的轨迹，如精子、微生物和马达蛋白。将确定粒子轨迹和它们穿越多孔膜的能力之间的相关性，结果将成为设计自主粒子以增强通过结构化环境(如细胞外基质和多孔岩石)传输的基础。将通过对研究生和本科生的教育努力以及针对视障儿童的外联活动来补充这项研究。这项研究将通过选修课“胶体和界面工程”的一个新章节纳入化学工程课程。该职业奖将为巴吞鲁日社区学院的本科生提供研究机会，并为路易斯安那视障学校的视障学生提供外展活动。该职业奖旨在回答粒子传输中的一个基本问题：粒子运动对其在多孔介质中的空间导航能力有何影响？该项目将通过检测金属补丁微球在水介质中的运动来解决这个问题，这些微球通过交流电场驱动的感应电荷电泳在水介质中自动推进。该项目的目的是(1)加深对活性胶体的结构-运动学关系的理解，并阐明颗粒和片状对称性对胶体轨迹的作用；(2)为指导胶体的定向推进建立基础，并确定颗粒的空间取向与其轨迹之间的关系；(3)通过了解颗粒轨迹与其通过多孔膜的隧道效率之间的关系，开发增强空间导航的新原理。该奖项将介绍在交流电场中指导有源粒子运动学的新方法，并将这些知识应用到复杂的结构化环境中。利用非线性粒子轨迹进行有效空间导航的原则可能不仅限于胶体运输；它们还可能适用于各种问题，如行人在人群中导航。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。

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.