Synthesizing 3D Metamaterials for RF, Microwave and THz Applications

该项目的目的是设计和制造3D电磁超材料，用作从可见光到无线电频率的应用的构建块。所提出的结构将是快速有效的增材制造（AM）技术的结果，该技术利用适当的材料，结合表面功能化方法，如电镀或溅射沉积。本研究是更大的“SYMETA”项目的一部分，福尔斯属于EPSRC“微电子器件技术”研究领域。超材料的设计和制造过程中的一个关键因素是其应用所针对的工作波长。更具体地，3D超原子的尺寸需要在工作波长的亚波长尺度内。出于这个原因，对于跨越所有感兴趣的长度尺度的一组制造技术存在很高的需求。一般概念是将3D超材料构建在电介质模具上。在毫米-厘米尺度上，人们可以采取很多方法，其中之一是印刷和油漆方法。这是一个两步的过程，其中印刷电介质形式，然后填充导电涂料。在我们的案例中，ABS用作电介质，导电涂料由铜颗粒和粘合剂组成。可替代地，可以通过使用多材料打印机（诸如体素8模型）来同时打印电介质和导电部分。使用PLA和两亲性银纳米颗粒油墨。最后，还可以选择在低温烧结陶瓷内印刷固体银导体。整个合奏制作在玻璃基板上。最后一种方法仍在开发中，但有可能达到微米级的分辨率。3D打印方法很难达到这种规模的分辨率，因此这是至关重要的，因为它将分辨率极限推得更高。3D超材料制造的最新发展已经成功地用导电材料（例如铜）覆盖超材料的表面，以便增加它们的导电性。对超材料的研究应致力于利用不同的技术来制造基于超材料的设备的潜力。结论所制造的3D超材料将被用作制造从MHz到THz的完全可操作的超材料设备的构建块。在做任何其他事情之前，应该对现有材料进行深思熟虑的研究，以便对手头的问题有深刻的理解。广泛使用的CST微波工作室可以提供关于不同几何形状和它们之间的安排的宝贵见解。该项目最大的挑战是从厘米到微米的尺寸范围内创建功能原型。到项目结束时，我们希望已经建立了一个完整的制造过程，其中基于3D超材料的设备可以在所有感兴趣的长度尺度上高效快速地生产。

INTRODUCTIONThe aim of this project is to design and fabricate 3D electromagnetic metamaterials, to be used as building blocks for applications ranging from visible to radio frequencies. The proposed structures will be the result of rapid and efficient Additive Manufacturing (AM) technologies utilizing appropriate materials, combined with surface functionalization methods, such as Electroplating or Sputter Deposition. This research is part of the larger "SYMETA" project and falls within the EPSRC "Microelectronic device technology" research area.FABRICATIONA crucial factor in the design and fabrication process of metamaterials is the operating wavelength the application is aimed at. More specifically, the size of the 3D meta-atoms needs to be in the subwavelength scale of the operating wavelength. For that reason, there is a high demand for a set of fabrication techniques across all length scales of interest. The general concept is to have the 3D metamaterials built on a dielectric mold. In the mm-cm scale, one can take quite a few approaches, one of which is the print-and-paint methods. This is a two-step process, where the dielectric form is printed and then filled with conductive paint. In our case, ABS is used as dielectric and the conductive paint consists of copper particles and a binder. Alternatively, the dielectric and conductive parts can be printed simultaneously by using a multi-material printer, such as the voxel 8 model. PLA and ambiphilic silver nanoparticle inks are used. Finally, there is the option of printing solid silver conductors inside a low temperature sintering ceramic. The whole ensemble is fabricated on a glass substrate. The last method is still under development but can potentially reach a resolution in the micrometre scale. 3D printing methods are having a hard time reaching resolution in this scale, so this is crucial because it pushes the resolution limit even higher. Recent developments in 3D metamaterial manufacturing have successfully covered the surface of the metamaterial with a conductive material, e.g. Copper, in order to increase their electrical conductivity. Research on metamaterial should adress the potential of utilizing different technologies for manufacturing metamaterial-based devices. CONCLUSIONSThe fabricated 3D metamaterials will be used as building blocks for manufacturing fully operational metamaterial devices operating from MHz to THz. Before anything else, a thoughtful study of the available materials, should take place, in order to cultivate a deep understanding of the matter at hand. The widely used CST Microwave Studio can provide invaluable insight about different geometries and arrangements between them. The greatest challenge of the project is the creation of functional prototypes from a size range between cm-micrometre. By the end of the project, we hope to have established a thorough fabrication process, in which 3D metamaterial-based devices can be efficiently and rapidly produced across all length scales of interest.