Emergent Stereoselective Interactions and Self-recognition in Polar Chiral Active Ellipsoids

TL;DR

This study demonstrates that chiral activity in polar active ellipsoids induces stereoselective interactions and self-recognition, affecting collective behavior and relaxation dynamics in active matter systems.

Contribution

It introduces a method to tune chiral activity in 3D-printed ellipsoids and reveals stereoselective interactions and self-recognition in active matter.

Findings

Heterochiral dimers move collectively as a single unit.

Homochiral dimers form immobile spinners.

Changing chirality alters collective relaxation in active liquids.

Abstract

In many active matter systems, particle trajectories have a well-defined handedness or chirality. Whether such chiral activity can introduce stereoselective interactions between particles is not known. Here we developed a strategy to tune the nature of chiral activity of 3D-printed granular ellipsoids without altering their shape or size. In vertically agitated monolayers of these particles, we observed two types of dimers form depending on the chirality of the pairing monomers. Heterochiral dimers moved collectively as a single achiral active unit, while homochiral ones formed a translationally immobile spinner. In active racemic mixtures, the former was more abundant than the latter indicating stereoselectivity. Through dimer lifetime measurements, we provide compelling evidence for chiral self-recognition in mixtures of particles with different chiral activities. We finally show that changing only the net chirality of a dense active liquid from a racemic mixture to an enantiopure liquid fundamentally alters its nature of collective relaxation.