Smart, Living & Active Matter - Leiden

Leiden Institute of Physics

About us

The SLAM - Smart, Living, & Active Matter - initiative unites theory and experimental groups of the Leiden Institute of Physics. It currently gathers the groups of Luca Giomi, Louise Jawerth, Daniela Kraft, Martin van Hecke, Silke Henkes and Alexandre Morin.

Coming up next

2024-02-29 - 13:30 @ Gorter room

SLAM seminar: Jack Binysh (Luca's guest)

Active Elasticity in non-reciprocal robotic metamaterials

Non-reciprocal interactions in active elastic media cause work cycles and wave propagation forbidden in equilibrium. These linear phenomena offer a route to designing autonomous materials that spontaneously crawl, roll or swim. Yet these same phenomena also render non-reciprocal materials hard to design, and force us to reckon with active elastodynamics beyond the linear regime.
In this talk I will describe our current work on rationally designing non-reciprocal materials made of robots, and modelling their collective dynamics. First I will show that odd elasticity, the continuum hallmark of microscopic non-reciprocity, emerges in a broad range of lattices made of non-reciprocal springs. Strikingly however, we find that the strength of odd response strongly depends on the precise lattice geometry. Hyperstatic lattices are needlessly hard to actuate, leading to sub-optimal odd response. By contrast, we find that in overly floppy lattices, zero modes couple to microscopic non-reciprocity, destroying odd moduli entirely. By avoiding these pitfalls, we identify optimal design principles for building odd lattices.
After connecting microscale non-reciprocity to macroscale elasticity, I will then present a continuum model of nonlinear odd elasticity, benchmarked against microscopic simulation and table-top experiments. Combining non-reciprocity and non-linearity in momentum-conserving materials yields long-wavelength instabilities and travelling nonlinear patterns. Strikingly, momentum conservation causes these emergent patterns to coarsen over time. As a result, these active metamaterials spontaneously rid themselves of disorder in favour of coherent motion. We then explore how this coarsening can respond to environmental stimuli, leading to a toolkit of distinct patterns for designing locomotion and actuation.