Phase coherence and disorder-induced wave propagation in micromotor arrays

TL;DR

This study investigates how microscopic rotary motors self-organize into phase-coherent structures and propagate signals, revealing insights into biological wave phenomena and potential applications in synthetic active materials.

Contribution

It demonstrates phase coherence and wave propagation in self-organized rotary motor arrays, highlighting the role of disorder in signal transmission in synthetic systems.

Findings

Motors form antiferromagnetic-like order

Emergence of phase coherence in rotor precession

Disorder enables phase wave propagation

Abstract

Machines are designed, assembled, and programmed to convert power into predetermined dynamics and functions. In contrast, living systems such as interacting cells and animal groups self-organize, synchronize, and perform complex tasks without predefined patterns. Inspired by these decentralized architectures, experiments have shown that small assemblies of elastically coupled self-propelled robots can achieve two fundamental functionalities observed in nature: collective motion and oscillatory deformations. However, biological inspiration has steered research toward translational self-propulsion, while active rotation remains an underexplored route to designing broader animate materials. Here, we study the self-organization of microscopic metamachines composed of thousands of 3D-printed rotary motors. We first demonstrate and explain how motors precessing in unspecified directions collectively arrange their dynamics into a pristine antiferromagnetic phase. Next, we elucidate the emergence of spatiotemporal order in the form of phase coherence in the rotors' precession. Finally, we show how quenched disorder initiates the free propagation of phase waves across self-organized regions with mismatched rotation speeds. Our results suggest that spinner-based metamachines could illuminate metachronal-wave formation in living systems, and signal propagation in synthetic animate materials.