An Integrated Approach to Designing and Fabricating Engineered Dielectric Metamaterials for Energy Harvesting Applications

该补助金支持基础知识的研究，以设计和制造具有工程热辐射特性的宏观介电超材料，用于能量收集应用。介电超材料是一种复合结构，它包括嵌入在基质材料（如聚合物）中的纳米或微米级介电颗粒，它们显示出传统材料中不存在的不寻常特性。通过改变超材料设计的可调参数，包括介电纳米颗粒材料、形状、尺寸、尺寸分布、取向、布置和体积分数以及基质材料，可以设计具有独特热辐射性质的超材料，例如具有红外波长的激光类发射的热源。然而，目前还没有方法来确定具有所需热辐射特性的介电超材料的微观结构，也没有方法来确定其宏观尺度的制造。该项目推导出计算实现用户指定的热辐射特性所需的超材料微结构的基本理论，并基于超声引导自组装实现可扩展的制造工艺，以制造宏观介电超材料。具有工程热辐射特性的介电超材料可以在能量收集方面发挥关键作用，例如回收计算机和手机的低温废热。这项研究促进了本科生和研究生，特别是代表性不足的少数民族，在研究中的参与，并通过夏令营培养妇女在工程方面的研究经验。该奖项的研究目标是制定和验证设计和制造具有用户指定热辐射特性的宏观介电超材料的综合方法。为了实现这一目标，介电超材料的微结构和它们的热辐射性能之间的关系，建立了一个基于随机麦克斯韦方程的数值精确的框架。研究是由逆方法的方法，其中涉及约束优化和边界元法。一个逆的方法来实现，以确定所需的超材料的微结构，以创建所需的热辐射性能。设计用于收集低温废热的宏观介电超材料由聚合物介质中的介电纳米颗粒组成，该聚合物介质使用可扩展的超声定向自组装技术制造，该技术涉及在三维超声节点处钉扎纳米颗粒。逆方法计算超声换能器参数，其建立组装从超材料设计获得的用户定义的纳米颗粒图案所需的波场。特别是，研究重点是形成具有大颗粒负载的工程超材料，这是一个特别的挑战。在这个项目中产生的新的基础科学知识被打包在一个通用的软件工具中，该软件工具将大多数工程超材料的设计和制造与用户指定的属性相集成。这个奖项反映了NSF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。

This grant supports research into fundamental knowledge to design and fabricate macroscale dielectric metamaterials with engineered thermal radiative properties for energy harvesting applications. Dielectric metamaterials are composite structures that comprise nano- or microscale dielectric particles embedded in a matrix material, such as polymer, and they display unusual properties that do not occur in conventional materials. By varying the adjustable parameters of the metamaterial design, including the dielectric nanoparticle material, shape, size, size distribution, orientation, arrangement, and volume fraction and the matrix material, it is possible to engineer metamaterials with unique thermal radiative properties, such as thermal sources with laser-like emission in the infrared wavelength. However, no methodology exists to determine the microstructure of a dielectric metamaterial with the desired thermal radiative properties nor its fabrication at the macroscale. This project derives the fundamental theory to calculate the metamaterial microstructure required to achieve user-specified thermal radiative properties and implements a scalable manufacturing process, based on ultrasound directed self-assembly, to fabricate macroscale dielectric metamaterials. Dielectric metamaterials with engineered thermal radiative properties can play a critical role in energy harvesting, such as recycling low-temperature waste heat from computers and cell phones. This research promotes the participation of undergraduate and graduate students, especially under-represented minorities, in research, and fosters research experiences for women in engineering via summer camps. The research objective of this award is to formulate and validate an integrated approach to designing and manufacturing macroscale dielectric metamaterials with user-specified thermal radiative properties. To accomplish this objective, the relationship between the microstructure of dielectric metamaterials and their thermal radiative properties are established via a numerically exact framework based on the stochastic Maxwell equations. The research is driven by inverse method approaches, which involve constrained optimization and the boundary element method. An inverse method is implemented to determine the metamaterial microstructure required to create the desired thermal radiative properties. Macroscale dielectric metamaterials, designed for harvesting low-temperature waste heat, consist of dielectric nanoparticles in a polymer medium that are fabricated using a scalable ultrasound directed self-assembly technique, which involves pinning nanoparticles at ultrasound nodes in three-dimensions. An inverse method computes the ultrasound transducer parameters that establish the wave field required to assemble a user-defined pattern of nanoparticles obtained from the metamaterial design. In particular, the research focuses on forming engineered metamaterials with large particle loadings, which is a particular challenge. The new basic science knowledge generated during this project is packaged in a generalized software-tool that integrates the design and manufacture of most engineered metamaterials with user-specified properties.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.