Unraveling Modular Microswimmers: From Self-Assembly to Ion-Exchange Driven Motors

TL;DR

This paper investigates the self-assembly and propulsion mechanisms of modular microswimmers driven by ion-exchange, combining experiments, theory, and simulations to reveal how these active particles move and can navigate complex environments.

Contribution

It uncovers the self-assembly process and the working mechanism of ion-exchange driven motors in modular microswimmers, filling a key knowledge gap.

Findings

Unveiled the self-assembly process of modular microswimmers.

Identified the propulsion mechanism of ion-exchange driven motors.

Demonstrated microswimmers can navigate complex environments and move uphill.

Abstract

Active systems contain self-propelled particles and can spontaneously self-organize into patterns making them attractive candidates for the self-assembly of smart soft materials. One key limitation of our present understanding of these materials hinges on the complexity of the microscopic mechanisms driving its components forward. Here, by combining experiments, analytical theory and simulations we explore such a mechanism for a class of active system, modular microswimmers, which self-assemble from colloids and ion-exchange resins on charged substrates. Our results unveil the self-assembly processes and the working mechanism of the ion-exchange driven motors underlying modular microswimmers, which have so far been illusive, even qualitatively. We apply these motors to show that modular microswimmers can circumvent corners in complex environments and move uphill. Our work closes a central knowledge gap in modular microswimmers and provides a facile route to extract mechanical energy from ion-exchange processes.