Neuron‐Inspired Steiner Tree Networks for 3D Low‐Density Metastructures

Abstract

Three-dimensional (3D) micro-and nanostructures have played an important role in topological photonics, microfluidics, acoustic, and mechanical engineering. Incorporating biomimetic geometries into the design of metastructures has created low-density metamaterials with extraordinary physical and photonic properties. However, the use of surface-based biomimetic geometries restricts the freedom to tune the relative density, mechanical strength, and topological phase. The Steiner tree method inspired by the feature of the shortest connection distance in biological neural networks is applied, to create 3D metastructures and, through two-photon nanolithography, neuron-inspired 3D structures with nanoscale features are successfully achieved. Two solutions are presented to the 3D Steiner tree problem: the Steiner tree networks (STNs) and the twisted Steiner tree networks (T-STNs). STNs and T-STNs possess a lower density than surface-based metamaterials and that T-STNs have Young's modulus enhanced by 20% than the STNs. Through the analysis of the space groups and symmetries, a topological nontrivial Dirac-like conical dispersion in the T-STNs is predicted, and the results are based on calculations with true predictive power and readily realizable from microwave to optical frequencies. The neuron-inspired 3D metastructures opens a new space for designing low-density metamaterials and topological photonics with extraordinary properties triggered by a twisting degree-of-freedom.

Two‐Photon Polymerization Lithography for Optics and Photonics: Fundamentals, Materials, Technologies, and Applications

“…The technology of TPL is well developed so far to fabricate 3D micro or nanostructures for optics and photonics, including photonic crystals, [269] metamaterials, [270] metasurfaces, [271] and biomedical engineering. [272] However, due to the diffraction limited nature of the focusing process and the single voxel fabrication scheme in TPL, there exist several technical challenges that hinder TPL in achieving high-quality 3D structures, such as spherical aberration, elongation of the writing voxel, and low fabrication efficiency for volumetric structures.…”

“…[312,313] Another popular strategy in complex beam shaping in TPL is the application of galvo mirrors, or the galvo dithering (GD) technique. [270] GD technique has been proved to be highly useful for photonic applications, such as optical activity, [314] fiber-optical microendoscopy, [315] and circular dichroism. [316] It contributes to preserving the circular cross-section and smoothness of the micro structure, and thus maintaining the unique photonic properties.…”

All-Nanochitin-Derived, Super-Compressible, Elastic, and Robust Carbon Honeycombs and Their Pressure-Sensing Properties over an Ultrawide Temperature Range

“…Specifically, anisotropic microstructure designs such as cellular-like, lamellar-like, wood-like, and honeycomb-like anisotropic microstructures could maximize the elasticity and fatigue resistance of the aerogels in the direction perpendicular to the anisotropic microstructures. Inspired by natural honeycombs and their anisotropic microstructures, it has been verified that honeycomb-structured aerogels exhibited apparent densities similar to those of typical aerogels but were structurally robust because the cell walls were closely connected and formed a “Steiner tree” geometry . This could efficiently dissipate mechanical strength and guide the deformation, thus avoiding locally large deformation and structural failure .…”

“…Inspired by natural honeycombs and their anisotropic microstructures, 23 it has been verified that honeycomb-structured aerogels exhibited apparent densities similar to those of typical aerogels 24 but were structurally robust because the cell walls were closely connected and formed a "Steiner tree" geometry. 25 This could efficiently dissipate mechanical strength and guide the deformation, thus avoiding locally large deformation and structural failure. 26 For example, Ding et al developed an elastic composite carbon aerogel with anisotropic "Steiner tree" microstructures based on carbonized konjac glucomannan and SiO 2 nanofibers.…”

Single‐Step 3D Printing of Micro‐Optics with Adjustable Refractive Index by Ultrafast Laser Nanolithography

“…The field of micro-optics made by Multi-Photon Lithography (MPL) [1,2] has been significantly growing for more than a decade DOI: 10.1002/adom.202300258 and has accelerated dramatically over the last five years. [3] Importantly, it empowers conceptually novel scientific research topics [4,5] and at the same time is entering industrial applications where the standardization of fabrication and reliable performance protocols are crucial. [6,7] Though MPL as a technique is becoming recognized as additive manufacturing for highefficiency advanced micro-optical elements and photonic bonds, which even enables 3D printing of inorganic glass-ceramic materials [8] suitable for a previously inaccessible range of durable compound microoptics.…”