Investigation of Microsphere Convective Deposition for Photonic and Biological Applications

CBET-0828426吉尔克里斯特这项拟议的研究将对使用对流自组装沉积单层粒子所涉及的物理学进行基本描述。在衬底上绘制一个蒸发的半月面，这是一个与“咖啡环效应”和朗缪尔-布洛杰特技术相关的过程，形成了从随机和有序的亚单层到有序的多层膜的颗粒结构。尽管许多最近开发的过程利用了这项技术，但与粒子对流和自组装有关的基本物理问题仍然存在。单层沉积的原位研究将使用高速共聚焦激光扫描显微镜进行。初步结果表明，许多以前没有考虑到的参数影响沉积，各种机制在沉积之前在薄膜中产生微球预对准。结合以前未探索过的加工、悬浮和衬底条件的实验将被用来开发一个模型，以阐明将可控的宏观性能与微观结构联系起来的机制。胶体单分子膜的制备将直接用于两个特定的应用。GaN/空气界面的折射率失配抑制了InGaN发光二极管(LED)的性能。所提出的工艺将用于制造微透镜阵列，其中微结构决定光提取效率。初步结果表明，光输出功率增加了219%。同时，设计标记抗体的单层阵列，用于全血检测CD4+淋巴细胞，将使艾滋病毒/艾滋病的筛查得到加强。这些沉积的单层的微结构将决定靶细胞的捕获效率和增殖，并使这些细胞能够释放以供分析。更广泛的影响：尽管胶体对流沉积被用于许多技术，但人们对基本物理学知之甚少。这项研究将根据沉积过程中直接三维粒子跟踪获得的各种表面和悬浮物属性的观察结果，开发一个预测模型。通过这项研究，控制这种微观结构的重要性将在两个对各自行业具有重大潜在影响的应用中得到证明。首先，使用该技术制造的微透镜阵列具有超越当前最先进的LED光子提取的潜力，允许工业应用的放大，并且与当前通过电子束光刻进行表面图案化的技术相比成本低。在全血分析中，这项技术可以推广到各种检测方案，并将有助于开发一种旨在为缺乏适当医疗资源的地区带来低成本检测的过程。这项工作将直接提供研究生和本科生在一个领域的教育机会，该领域是几个关键技术研究领域的汇合点，包括微流体、悬浮运输、光子学和生物工程。

CBET-0828426GilchristThe proposed research will generate a fundamental description of the physics involved in the deposition of a monolayer of particles using convective self-assembly. Drawing an evaporating meniscus across a substrate, a process related to the "coffee ring effect" and the Langmuir-Blodgett technique, forms a structure of particles ranging from random and ordered sub-monolayer to well-ordered multilayers. Although many recently developed processes take advantage of this technique, primary questions remain regarding the fundamental physics involved with particle convection and self-assembly. In situ investigation of monolayer deposition will be performed using high speed confocal laser scanning microscopy. Preliminary results suggest many parameters not previously considered affect deposition and various mechanisms generate microsphere pre-alignment in the thin film prior to deposition. Experiments that incorporate processing, suspension, and substrate conditions not previously explored will be used to develop a model to shed light onto the mechanisms that link the controllable macroscopic properties to the microstructure. Fabrication of colloidal monolayers will be used directly in two specific applications. Performance of InGaN light emitting diodes (LEDs) is inhibited by the index mismatch of the GaN/air interface. The proposed process will be used to fabricate microlens arrays where the microstructure determines the light extraction efficiency. Preliminary results demonstrate increased light output power by 219%. In a parallel effort, design of monolayer arrays labeled with antibodies for whole blood detection of CD4+ lymphocytes will enable enhanced screening for HIV/AIDS. The microstructure of these deposited monolayers will dictate the capture efficiency and proliferation of target cells and enable release of these cells for analysis. Broader Impacts: Although colloidal convective deposition is used in many technologies, the fundamental physics is poorly understood. This research will develop a predictive model based on observations obtained from direct 3D particle tracking during deposition for various surface and suspension properties. Through this research, the importance of controlling this microstructure will be demonstrated in two applications that have significant potential impact on their respective industries. First, the microlens arrays fabricated using this technique have the potential to surmount the current state-of-the-art LED photon extraction, allows scale-up for industrial applications, and is low-cost as compared to current techniques of surface patterning via electron beam lithography. In whole blood analysis, this technique can be generalized for a variety detection schemes and will aid development of a process that aims to bring low cost detection to regions lacking proper medical resources. This work will directly provide both graduate and undergraduate educational opportunities in an area at the convergence of several technologically-critical research areas including microfluidics, suspension transport, photonics, and bioengineering.