Confinement-induced phase transitions of Living Chiral Crystal

Active crystal is a form of active matter with crystalline order, where the interplay between activity, elasticity and plasticity often leads to unusual dynamics. Self-assembled by swimming starfish embryos, the recently discovered Living Chiral Crystal (LCC) is an active crystal featuring non-reciprocal (chiral) interactions never found in a passive crystal. Here, we show how external boundary interaction and grain boundary/void connectivity induce different dynamics in LCC. Specifically, we confine LCC in regular polygons and circles, control void fraction, adjust grain boundary percolation, and observe phase transitions of LCC from local fluctuations to rigid body rotations and chaotic mixing. These results give another glimpse into how LCC acts as a model system to uncover new and rich properties of non-reciprocal active matter.