Person:

Overvelde, Johannes

Advances in fabrication technologies are enabling the production of architected materials with unprecedented properties. Most such materials are characterized by a fixed geometry, but in the design of some materials it is possible to incorporate internal mechanisms capable of reconfiguring their spatial architecture, and in this way to enable tunable functionality. Inspired by the structural diversity and foldability of the prismatic geometries that can be constructed using the snapology origami technique, here we introduce a robust design strategy based on space-filling tessellations of polyhedra to create three-dimensional reconfigurable materials comprising a periodic assembly of rigid plates and elastic hinges. Guided by numerical analysis and physical prototypes, we systematically explore the mobility of the designed structures and identify a wide range of qualitatively different deformations and internal rearrangements. Given that the underlying principles are scale-independent, our strategy can be applied to the design of the next generation of reconfigurable structures and materials, ranging from metre-scale transformable architectures to nanometre-scale tunable photonic systems.

Dynamically tunable three-dimensional photonic materials offer potential for the development of novel optical technologies. For spectral ranges of interest, however, the systematic and high-throughput characterization of their optical responses as a function of physical deformation remains elusive. This arises from challenges associated with their nanoscale fabrication, deformation, and structural and optical characterization. By exploiting the scale-invariance of Maxwell’s equations and of the elastic material response, we demonstrate the systematic characterization of a tunable macro-scale replica of the gyroid structure found in Parides sesostris butterflies’ wing scales. This scaled replica of the natural photonic crystal was fabricated from a UV cross-linkable elastomer capable of large-range reversible linear deformation via high-resolution additive manufacturing. The controlled deformation of this periodic elastomer-based photonic crystal allowed for a systematic variation of its optical response. Microwave spectroscopy, electromagnetic and mechanical Finite-Element Analysis, and x-ray computed micro-tomography were used to gain a detailed understanding of the gyroid’s compression-induced deformation and the resulting modification of its electromagnetic properties. This approach enables controlled and rapid prototyping and optimization of any desired photonic architecture at macroscopic dimensions prior to the fabrication of its nano/microscopic analogue relevant for manipulating smaller wavelength radiation for use in a wide range of technological applications.