Capillary-Assisted Printing of Structured Colloidal Monolayers

由微米大小的颗粒制成的薄膜可用于传感、光学涂层、防伪和电子。这些应用需要严格控制薄膜中每个粒子的位置和方向。当代的制造技术无法提供这种精度。该奖项支持基础研究，以创建一种新的增材制造技术，该技术使用液滴的界面（模板）来构建有序的颗粒膜。粒子被传送到模板的表面，在界面上存在的微小力的作用下聚集在一起。液滴蒸发后，粒子组件被映射到下面的衬底上，形成干燥有序的薄膜。研究团队将结合计算机模拟和实验测试来发现加工条件与薄膜沉积特性之间的关系。新的知识将导致一个可扩展的平台，以制造具有复杂图案的薄膜材料的粒子构建块。这项拨款的教育部分将通过关注学生的研究经验和公众宣传来激励和培养具有竞争力的先进制造业劳动力。学校将开展以课程为基础的暑期项目和社区活动，吸引不同层次的学生和公众参与。该奖项将在工程薄膜材料方面开辟新的领域，并有助于美国在先进制造领域的全球领导地位。该项目的目标是通过利用界面毛细管组装和电喷雾靶向的独特能力，创造一种用于制造具有分层微结构的干胶体单层的增材技术。新方法将使用几何控制的液滴作为模板，通过电喷雾将微粒的二维结晶超结构直接传递到液滴表面。在液滴模板蒸发后，干燥的单层将转移到底层结构。为了充分发挥该技术的应用潜力，本研究将填补在非均匀弯曲界面上毛细管组装和蒸发诱导输运复杂相互作用方面的知识空白。研究团队将创建表面演化模型和晶格玻尔兹曼模拟来预测界面演化、液滴流体动力学和粒子输运。先进的流动成像和粒子跟踪方法将应用于验证模型和揭示结构形成的潜在物理。将进行电喷雾定向和蒸发实验，以验证与毛细迁移对齐的表面流动需要在干燥形式下形成结构单层的假设。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。

Thin films made of micrometer-sized particles can be used in sensing, optical coatings, anti-counterfeiting, and electronics. These applications require that the position and orientation of each particle in the film be tightly controlled. Contemporary manufacturing techniques are unable to provide this level of precision. This award supports fundamental research to create a new additive manufacturing technique that uses the interface of a liquid droplet (a template) to build ordered particle films. The particles are delivered to the surface of the template, where they assemble under the subtle forces that exist at the interface. The droplet evaporates and the particle assembly is mapped to the underlying substrate, creating a dry ordered thin film. The research team will combine computer simulations and experimental testing to discover the relationship between the processing conditions and the characteristics of the thin film deposits. The new knowledge will lead to a scalable platform to manufacture thin film materials with complex patterns from particle building blocks. The educational component of this grant will motivate and train a competitive workforce in advanced manufacturing by focusing on student research experiences and public outreach. A course-based summer program and community activities will be developed to engage students at different levels and the general public. This award will break new ground in engineering thin film materials and contribute to U.S. global leadership in advanced manufacturing.The goal of this project is to create an additive technique for manufacturing dry colloidal monolayers with hierarchical microstructures by exploiting the unique capabilities of interfacial capillary assembly and electrospray targeting. The new method will use a geometrically controlled droplet as a template to assemble two-dimensional crystalline superstructures of microparticles delivered directly to the droplet surface by electrospray. A dry monolayer will be transferred to the underlying structure upon the evaporation of the droplet template. To realize the full application potential of this technique, this research will fill the knowledge gap on the complex interplay of capillary assembly and evaporation-induced transport on non-uniformly curved interfaces. The research team will create surface-evolving models and lattice Boltzmann simulations to predict the interface evolution, droplet hydrodynamics, and particle transport. Advanced flow imaging and particle tracking methods will be applied to validate the model and uncover the underlying physics of structure formation. Electrospray targeting and evaporation experiments will be conducted to test the hypothesis that a surface flow aligned with capillary migration is required to form a structured monolayer in a dry form.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.