Collaborative Research: Electric-field Directed Assembly of 3D Chiral Metamaterials

手性是生命物质的基本特征。手征超材料是由具有手征性的周期性金属电介质结构单元组成的工程结构。单个构建块的共振和邻居之间的强耦合允许实现奇异的电磁特性，如负折射率和巨圆二色性。手性超材料可以彻底改变许多现代技术，包括超透镜，光通信，隐身设备和高分辨率传感器。然而，三维手性超材料非常难以制造，特别是以经济和大规模的方式。这项研究将利用非对称粒子作为积木，并利用随时间变化的电场来引导这些粒子组装成长程周期性手性结构。基于溶液的工艺可以潜在地显著降低制造成本。电极设计与现有微电子制造基础设施的兼容性也将为新兴应用的创新超材料商业化打开大门。研究团队还将让高中生和本科生参与沉浸式研究体验。将与K-12教师合作开发学习模块，如"胶体，表面活性剂和我们的日常生活"和"改变我们生活的光学技术"。研究结果亦会纳入多个跨学科课程的发展中，例如“软材料工程学”及“纳米技术：从分子到机器”。这个合作项目的目标是利用电场将Janus金属电介质颗粒组装成手性簇的周期性阵列，作为制造三维手性超材料的有效自下而上的路线。具有增加的形态复杂性的颗粒将通过掠射角沉积被制造为构建块。将建立一个液体电极单元，用于通过三维时变电场操纵Janus粒子。库仑，偶极，和电流体动力学相互作用将被利用来引导Janus粒子组装成手性团簇。进一步操纵电场的手性将外消旋混合物转化为对映体纯的簇。在近红外和可见光区域，将测量和探索所制造的结构的光子响应及其应用。还将进行数值模拟，以阐明粒子组装机制，它们的光学性质，并指导实验优化。该项目的协作和迭代性质将揭示基本构建模块的设计，晶格对称性的控制和手性超材料的目标光子特性之间的相互关系。

Chirality is a fundamental characteristic of living matter. Chiral metamaterials are engineered structures composed of periodic metallodielectric building blocks that exhibit chirality. The resonance of individual building blocks and strong coupling between neighbors allow the realization of exotic electromagnetic properties such as negative refractive index and giant circular dichroism. Chiral metamaterials could revolutionize many modern technologies including superlenses, optical communication, cloaking devices, and high resolution sensors. Three-dimensional chiral metamaterials are, however, extremely difficult to fabricate especially in an economical and large scale fashion. This research will utilize asymmetric particles as building blocks and exploit a time-varying electric field to guide the assembly of these particles into long-range periodic chiral structures. The solution-based process could potentially reduce the fabrication cost significantly. The compatibility of the electrode design with existing microelectronic manufacturing infrastructures will also open the door to commercialize innovative metamaterials for emerging applications. The research team will also engage both high school and undergraduate students with immersive research experiences. Learning modules such as "Colloids, surfactants, and our daily lives" and "Optical technology that changes our lives" will be developed in collaboration with K-12 teachers. The research findings will also be included in the development of several multi-disciplinary courses such as "Engineering of Soft Materials" and "Nanotechnology: From Molecules to Machines". The goal of this collaborative project is to use electric fields to assemble Janus metallodielectric particles into a periodic array of chiral clusters as an efficient bottom-up route for making three-dimensional chiral metamaterials. Particles with increasing morphological complexity will be fabricated as building blocks by glancing angle deposition. A liquid electrode cell will be built for the manipulation of the Janus particles via time-varying electric fields in three-dimensions. The Coulomb, dipolar, and electrohydrodynamic interactions will be exploited to guide the assembly of Janus particles into chiral clusters. Further manipulation of the chirality of the electric fields will transform the racemic mixture into enantiomerically pure clusters. The photonic response of the fabricated structures and their applications will be measured and explored in both near-infrared and visible regions. Numerical simulations will also be performed to elucidate the particle assembly mechanisms, their optical properties, and guide experimental optimization. The collaborative and iterative nature of this project will reveal the interrelationship between the design of fundamental building blocks, control of lattice symmetry, and targeted photonic properties of chiral metamaterials.