The 2019 Motile Active Matter Roadmap

TL;DR

This paper provides a comprehensive overview of active matter, emphasizing its physical mechanisms, emergent collective behaviors, and interdisciplinary challenges in understanding and designing motile active systems across scales.

Contribution

It offers a detailed roadmap of the active matter field, highlighting recent advances, key challenges, and future directions for research and development.

Findings

Active matter exhibits complex, emergent collective behaviors.

Designs inspired by biological microswimmers enable synthetic active materials.

Understanding nonequilibrium dynamics is crucial for controlling active systems.

Abstract

Activity and autonomous motion are fundamental in living and engineering systems. This has stimulated the new field of active matter in recent years, which focuses on the physical aspects of propulsion mechanisms, and on motility-induced emergent collective behavior of a larger number of identical agents. The scale of agents ranges from nanomotors and microswimmers, to cells, fish, birds, and people. Inspired by biological microswimmers, various designs of autonomous synthetic nano- and micromachines have been proposed. Such machines provide the basis for multifunctional, highly responsive, intelligent (artificial) active materials, which exhibit emergent behavior and the ability to perform tasks in response to external stimuli. A major challenge for understanding and designing active matter is their inherent nonequilibrium nature due to persistent energy consumption, which invalidates equilibrium concepts such as free energy, detailed balance, and time-reversal symmetry. Unraveling, predicting, and controlling the behavior of active matter is a truly interdisciplinary endeavor at the interface of biology, chemistry, ecology, engineering, mathematics, and physics. The vast complexity of phenomena and mechanisms involved in the self-organization and dynamics of motile active matter comprises a major challenge. Hence, to advance, and eventually reach a comprehensive understanding, this important research area requires a concerted, synergetic approach of the various disciplines.