Microscale architected materials for elastic wave guiding: Fabrication and dynamic characterization across length and time scales

TL;DR

This paper introduces a scalable fabrication and characterization method for microarchitected elastic waveguides, demonstrating precise wave control and validation through experiments and simulations across multiple scales.

Contribution

It presents a novel fabrication and measurement protocol for micro-scale elastic waveguides, enabling detailed wave analysis and custom waveguide design.

Findings

Successful fabrication of scalable silicon-based waveguides

Accurate experimental and simulation correlation of wave propagation

Demonstration of arbitrary wave guiding via graded architectures

Abstract

We present an experimental protocol for the fabrication and characterization of scalable microarchitected elastic waveguides. Using silicon microfabrication techniques, we develop free-standing 2D truss-based architected waveguides with a maximum diameter of 80 mm, unit cells size of 100 micrometer, and minimum beam width of 5 micrometer, thus achieving scale separation. To characterize elastic wave propagation, we introduce a custom-built scanning optical pump-probe experiment that enables contactless excitation of elastic wave modes and full spatio-temporal reconstruction of wave propagation across hundreds of unit cells with sub-unit cell resolution. Results on periodic architectures show excellent agreement with finite element simulations and equivalent experimental data at larger length scales. Motivated by scalable computational inverse design, we fabricate a specific example of a spatially graded waveguide and demonstrate its ability to guide elastic waves along an arbitrary pre-designed path.