CAREER: Fluid Dynamics of Colloidal Crystal Film Deposition

CBET-0747917 Posner胶体晶体薄膜（CCF）正在开发中，可用作集成光学电路的光子晶体、超疏水表面以及用于生化分离的固态筛分基质。 胶体晶体膜由20层或更多层的面心立方堆积的纳米球（20-500 nm）组成。这些膜通常通过纳米级球体的非稀释胶体悬浮液的流体自组装过程沉积。 目前的CCF受到20-1000球体直径范围内的不希望的缺陷的困扰，这限制了器件的应用。溶剂蒸发和电泳沉积方法在很大程度上是通过反复试验开发的，并且缺乏对支配物理学的基本理解。控制胶体晶体膜结构和减少膜缺陷的能力受到沉积过程中流体输运的复杂作用的限制。 这些流动包括自由表面和电场与高体积分数悬浮液和局部变化的粘度，密度，表面张力，电导率和介电常数的耦合。它们是时间依赖性的，三维的，并表现出广泛的时间和长度尺度，使它们难以建模和观察。本研究探讨胶体晶体薄膜沉积的传输物理，其中高体积分数的胶体悬浮液流动与自由表面和电场。研制了一种高速旋转圆盘共聚焦显微镜，用于实时和空间测量三个速度分量和晶体结构。这项研究将使沉积无缺陷的胶体晶体薄膜和结构的一系列新兴技术。高速共聚焦系统将影响广泛的学科，包括微流体学，流变学，胶体科学和实时细胞成像。对胶体结晶的基本理解可以应用于分子结晶，如蛋白质结晶学。该计划将研究与指导，教育和推广相结合，影响从中学到研究生院的学生。这项研究包括发展一个中学外展计划？有流量吗？为凤凰城大都会地区代表性不足的中学生提供服务。 什么？有流量吗？该方案有三个阶段：外展模块直接激励1000名8年级学生学习数学，科学或工程; RET为中学教师提供研究经验和国家规定的专业培训;以及教育转移模块（ETM），将模块传达给各个中学。PI将扩大西班牙裔和美洲原住民的本科研究机会，他们在ASU的入学率相对较高，但在全国范围内的工程代表性较低。

CBET-0747917PosnerColloidal crystal films (CCF) are being developed as photonic crystals for integrated optical circuits, as super hydrophobic surfaces, and as solid-state sieving matrices for biochemical separations. Colloidal crystal films are comprised of 20 or more layers of face center cubic packed nanospheres (20-500 nm). These films are typically deposited by a fluid self-assembly process of a non-dilute colloidal suspension of nanoscale spheres. Current CCFs are plagued with unwanted defects in the range of 20-1000 sphere diameters that limit device applications. Solvent evaporation and electrophoretic deposition methods are largely developed by trial and error and suffer from a lack of fundamental understanding of the governing physics. The ability to control colloidal crystal film structure and reduce film defects is limited by the complex role of the fluid transport on the deposition process. These flows include the coupling of free surfaces and electric fields with high volume fraction suspensions and locally varying viscosity, density, surface tension, conductivity, and permittivity. They are time-dependent, three-dimensional and exhibit a wide range of time and length scales that make them difficult to model and observe. This research investigates the transport physics of colloidal crystal film deposition where high volume fraction colloidal suspensions flow with free surfaces and electric fields. A high-speed, spinning disk confocal microscope will be developed to measure the three velocity components and crystal structure in real-time and real-space. This research will enable depositions of defect-free colloidal crystal films and structures for a host of emerging technologies. The high speed confocal system will impact a wide range of disciplines including microfluidics, rheology, colloidal science, and real-time cellular imaging. Fundamental understanding of colloidal crystallization can be applied to molecular crystallization such as protein crystallography. This program integrates research with mentoring, education and outreach impacting students from middle school through graduate school. The study includes the development of a middle school outreach program ?got flow?? for underrepresented middle school students in the Phoenix metropolitan area. The ?got flow?? program has three phases: outreach modules directly inspiring 1000 8th graders to study math, science, or engineering; RET to provide research experience and state mandated professional training for middle school teachers; and educational transfer modules (ETM) that convey the modules to individual middle schools. The PI will expand undergraduate research opportunities for Hispanic and Native Americans who have relatively high enrollment at ASU, but low representation in engineering nationwide.