Odd chiral jamming in active granular materials

Jamming transitions represent a captivating phenomenon where disordered systems gain mechanical rigidity as density surpasses a critical threshold. While the mechanics of these transitions have been extensively explored in passive systems, the interplay between nonequilibrium activity, chirality, and jamming remains a frontier of discovery.  

 

Our current work delves into this uncharted territory by examining a 2D collective of self-propelling, chirally rotating starfish embryos. As density increases, these embryos exhibit a jamming transition marked by bursts of displacement chains and dynamic rearrangements, reminiscent of glassy systems yet imbued with chiral signatures.  

 

Intriguingly, as the embryos develop, short-range nematic order begins to emerge, introducing new structural patterns and orientational alignment. This evolution suggests that non-reciprocal interactions between the embryos could lead to unexpected, "odd" behaviors in the jamming transition. We aim to capture these phenomena using geometric order parameters like tension triangles, offering a novel lens to study active matter.  

 

This project blends experimental observation with theoretical insights, revealing the intricate and beautiful interplay between activity, structure, and emergent mechanics in living systems. It’s a step toward unraveling how nature's quirks, such as chirality, redefine the boundaries of classical physics.​