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arXiv · 2412.16658

Tunable Assembly of Confined Janus Microswimmers in Sub-kHz Electic Fields under Gravity

Carolina van Baalen·Laura Alvarez·Robert Style·Lucio Isa
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Abstract

Active systems comprising micron-sized self-propelling units, also termed microswimmers, are promising candidates for the bottom-up assembly of small structures and reconfigurable materials. Here we leverage field-driven colloidal assembly to induce structural transformations in dense layers of microswimmers driven by an alternating current (AC) electric field and confined in a microfabricated trap under the influence of gravity. By varying the electric field frequency, we realize significant structural transformations, from a gas-like state at high frequencies to dynamically rearranging dense crystalline clusters at lower frequencies, characterized by vorticity in their dynamics. We demonstrate the ability to switch between these states on-demand, showing that the clustering mechanism differs from motility-induced phase separation. Our results offer a valuable framework for designing high-density active matter systems with controllable structural properties, envisioned to advance the development of artificial materials with self-healing and reconfiguration capabilities.

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Carolina van Baalen, Laura Alvarez, Robert Style, Lucio Isa. 2024-12-21. Tunable Assembly of Confined Janus Microswimmers in Sub-kHz Electic Fields under Gravity. https://arxiv.org/abs/2412.16658

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