Metamaterial Architectures for Programmable Droplet Motion

这笔赠款支持控制液滴在固体表面上运动的基础研究。液滴控制问题与许多工业应用有关，从自干燥表面和通过液滴冷凝进行的热传递到水收集和生物医学分析。因此，在这个方向上的研究可以带来具有巨大社会影响的发现。大多数液滴运动控制的策略都包括通过化学或机械手段操纵与流体直接接触的表面，从而不可逆转地改变其默认属性。这个项目推广了一种不同的模式，利用移动的液滴和振动表面之间的相互作用。该项目的想法围绕着使用新兴的工程超材料概念来设计具有空间可编程振动响应的表面，从而允许根据需要改变液滴运动的可用景观。此外，将利用超材料与流体运动相结合的能力来设计直观的演示设备，允许用肉眼可视化复杂的弹性波现象，使它们成为科学推广和教授先进工程概念的理想选择。该项目的技术目标是设计振动超材料，以编程液体液滴在固体表面的运动。具体地说，这项研究的目的是实现控制策略，允许在振动状态为开时对流体运动进行深度操纵，同时保持关闭配置中的默认系统条件。利用共振超材料，可以调制表面不同区域的振动响应。通过结构设计和激发调节的适当相互作用，人们可以有选择地在选定的区域规划液滴脱钉的开始，从而根据几乎无穷无尽的空间模式在空间上设计可用的液滴运动景观。这种设计灵活性可以用于为液滴运动编写各种复杂的逻辑场景，例如基于液滴大小的集群和分离。这项调查得到了一系列桌面激光测振和高速成像实验的支持。这一奖项反映了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。

This grant supports fundamental research for controlling the motion of liquid droplets on solid surfaces. The problem of droplet control is relevant for numerous industrial applications, from self-drying surfaces and heat transfer via droplet condensation to water harvesting and biomedical analysis. Therefore, research in this direction can lead to discoveries with vast societal impact. Most strategies for droplet motion control involve doctoring, either chemically or mechanically, the surface that is in direct contact with the fluid, thus altering irreversibly its default properties. This project promotes a different paradigm that exploits the interaction between moving droplets and vibrating surfaces. The project idea revolves around the use of emerging notions of engineering metamaterials to design surfaces with spatially programmable vibrational response that allows to alter the available landscape of droplet motion on demand. In addition, the ability to couple metamaterials with fluidic motion will be exploited to design intuitive demonstration devices that allow visualizing, with the naked eye, complex elastic wave phenomena, making them ideal for scientific outreach and for teaching advanced engineering concepts.The technical objective of the project is to design vibrating metamaterials for programming the locomotion of liquid droplets on solid surfaces. Specifically, this research aims to realize control strategies that allow deep manipulation of the fluid motion when the vibrating state is on, while preserving the default system conditions in the off configuration. With resonant metamaterials, it is possible to modulate the vibrational response available in different regions of a surface. Through a proper interplay of structural design and excitation tuning, one can selectively program the onset of droplet depinning in select regions, thus spatially engineering the available landscape of droplet motion according to a virtually endless array of spatial patterns. Such design flexibility can be leveraged to program a variety of complex logic scenarios for droplet motion, such as clustering and segregation based on droplet size. The investigation is supported by a series of table-top experiments via laser vibrometry and high-speed imaging.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.