EAGER: A Novel Experiment to Study Interfacial Processes between Droplet and Patterned Surfaces

EAGER：研究液滴与图案表面之间界面过程的新颖实验

• 批准号: 1247512
• 负责人: K. Jimmy Hsia
• 金额: $ 15.13万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1247512&HistoricalAwards=false
• 关键词: EAGER; Novel; Experiment; Study; Interfacial

Hsia CBET - 1247512The proposed exploratory EAGER project aims at the first quantitative measurement of interfacial interactions between a droplet and a patterned substrate. A novel experimental technique is developed to quantitatively study the interaction forces as a function of the geometry and defect characteristics of the micropatterns. The system provides a quantitative testbed for long-standing theories of interfacial processes such as contact-line pinning under different geometric and chemical conditions for the first time, thus benefitting a huge variety of fields, including solid state physics, surface chemistry, and microfabrication. Intellectual MeritSubstrates with micropatterns, particularly those with a "forest" of micropillars interacting with small-scale droplets, have garnered enormous interest in recent years for their versatility and unusual properties, including wettability, adhesive energy, conductivity or capacitance. These patterns have potential applications in widespread industrial processes that rely on non-wetting surfaces that reject dirt, have low adhesive energy, reject water (e.g. coatings for windshields), resist condensation (e.g. in refrigeration devices), or are useful in pore filtration of gases (e.g. in micro fuel cells). Nevertheless, a quantitative understanding of droplet shapes and dynamics lags behind a large number of proof-of-principle experiments. In particular, very little is known about the effect of pattern and pillar geometry on the dynamics of contact line motion and the forces needed to sustain (or arrest) such motion. The proposed work will apply novel experimental techniques for simultaneous quantitative measurements of droplet shape and contact-line pinning forces, both with a spatial resolution at the single-defect level and capable of fast time resolution. The interaction of isolated defects of defined shape with contact lines has long been the subject of pinning theories, perceived as an idealization of the description of real contact line behavior. With high-speed photography and sensitive force sensors, forces and deformations of droplets and substrates in relative motion will be determined simultaneously by making crucial measurements for an accurate description of dynamical contact angle hysteresis as well as droplet repulsion, fragmentation, and coalescence on hydrophobic surfaces. The experiments can access and analyze a wide range of speeds beyond current experiments, in a regime highly relevant for applications. The proposed EAGER research proposal has the following objectives: (i) to seek an accurate understanding of contact line pinning and depinning from isolated defects, in an experimental system that can serve as a paradigm for defect pinning in broader contexts of interfacial processes; (ii) to acknowledge the effect of defect distribution and defect interaction on the contact line as a whole; (iii) to explore an innovative combination of experimental techniques, promising an improved set of tools for analyzing contact line motion on the microscale.Broader ImpactsThe Broader Impacts of the proposed work include those on the societal, group, and individual scales. The research provides fundamental insight in fields of great societal need: clean water, refrigeration, energy, and advanced manufacturing. The graduate and undergraduate students involved in the project will be trained in the areas of microfabrication, soft lithography, surface patterning, and other processes that are of great importance. The PI will also incorporate research results in existing courses and demonstrations. The PI has plans in place to boost the participation of members from under-represented groups by proactively participating in several on-campus/off-campus programs, including Women in Engineering Program, the Minority Engineering Program, and the McNair Scholar Program.

Hsia CBET - 1247512拟议的探索性 EAGER 项目旨在首次定量测量液滴和图案化基底之间的界面相互作用。开发了一种新颖的实验技术来定量研究作为微图案的几何形状和缺陷特征的函数的相互作用力。 该系统首次为长期存在的界面过程理论（例如不同几何和化学条件下的接触线钉扎）提供了定量测试平台，从而使固态物理、表面化学和微加工等众多领域受益。 具有微图案的基材，特别是那些具有与小尺寸液滴相互作用的微柱“森林”的基材，近年来因其多功能性和不寻常的特性（包括润湿性、粘合能、电导率或电容）而引起了人们的极大兴趣。 这些图案在广泛的工业过程中具有潜在的应用，这些过程依赖于非润湿表面，这些表面可以拒绝污垢、具有低粘合能、拒绝水（例如挡风玻璃涂层）、抵抗冷凝（例如在制冷设备中），或者可用于孔隙过滤气体（例如微型燃料电池）。 然而，对液滴形状和动力学的定量理解落后于大量原理验证实验。 特别是，关于图案和支柱几何形状对接触线运动动力学以及维持（或阻止）这种运动所需的力的影响知之甚少。 拟议的工作将应用新颖的实验技术来同时定量测量液滴形状和接触线钉扎力，两者都具有单缺陷水平的空间分辨率并且能够快速时间分辨率。 定义形状的孤立缺陷与接触线的相互作用长期以来一直是钉扎理论的主题，被视为真实接触线行为描述的理想化。 借助高速摄影和灵敏的力传感器，通过进行关键测量，可以同时确定相对运动的液滴和基底的力和变形，从而准确描述动态接触角滞后以及疏水表面上的液滴排斥、破碎和聚结。 这些实验可以在与应用高度相关的机制中访问和分析超出当前实验的各种速度。 拟议的 EAGER 研究计划具有以下目标：（i）在一个实验系统中寻求对接触线钉扎和孤立缺陷脱钉的准确理解，该系统可以作为更广泛的界面过程背景下缺陷钉扎的范例； (ii) 承认缺陷分布和缺陷相互作用对整个接触线的影响； (iii) 探索实验技术的创新组合，有望提供一套改进的工具来分析微观尺度上的接触线运动。更广泛的影响拟议工作的更广泛影响包括社会、群体和个人尺度上的影响。 该研究为社会急需的领域提供了基本见解：清洁水、制冷、能源和先进制造。 参与该项目的研究生和本科生将接受微加工、软光刻、表面图案化和其他重要工艺领域的培训。 PI 还将把研究成果纳入现有课程和演示中。 PI 已制定计划，通过积极参与多个校内/校外项目（包括女性工程项目、少数族裔工程项目和麦克奈尔学者项目）来提高代表性不足群体成员的参与度。