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

手性是生物体的一个基本特征。手性超材料是由具有手性的周期性金属介电构件组成的工程化结构。单个积木的共振和邻居之间的强耦合允许实现奇异的电磁特性，如负折射率和巨大的圆二向色性。手性超材料可能会给许多现代技术带来革命性的变化，包括超透镜、光通信、隐身设备和高分辨率传感器。然而，三维手性超材料的制造是极其困难的，特别是在经济和大规模的方式。这项研究将利用不对称粒子作为构建块，并利用时变电场来引导这些粒子组装成远程周期性手性结构。基于溶液的工艺可能会显著降低制造成本。电极设计与现有微电子制造基础设施的兼容性也将为将创新的超材料商业化应用于新兴应用打开大门。研究团队还将邀请具有身临其境研究经验的高中生和本科生参与。“胶体、表面活性剂与我们的日常生活”和“改变我们生活的光学技术”等学习单元将与K-12教师合作开发。研究成果还将被包括在几个多学科课程的开发中，如“软材料工程学”和“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金属介电粒子组装成周期性的手性团簇阵列，作为一种有效的自下而上的方法来制造三维手性超材料。通过掠角沉积，可以将形态越来越复杂的颗粒制成积木。将建立一个液体电极室，通过三维时变电场来操纵Janus粒子。库仑、偶极和电流体相互作用将被用来引导Janus粒子组装成手性团簇。进一步操纵电场的手性将把外消旋混合物转变为对映体纯净的团簇。制作的结构及其应用的光子响应将在近红外和可见光区域进行测量和探索。还将进行数值模拟，以阐明粒子组装的机制及其光学性质，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块的设计、晶格对称性的控制和手性超材料的目标光子性质之间的相互关系。

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.