Scalable Laser Manufacturing of High-Aspect-Ratio Superhydrophobic and Ferromagnetic Microcilia Arrays for Aqueous Droplet Transportation.

Abstract

Biological cilia exhibit metachronal movements that enable the expulsion of substances such as mucus and bacterial cells. Inspired by biological cilia, significant progress has been made in recent years in the development of artificial cilia. In particular, magnetic actuation has emerged as a prominent strategy for real-time, remote-controlled manipulation, offering noninvasive and reversible operation without inducing irreversible damage. However, the fabrication of artificial microcilia is currently constrained by limitations in achieving high aspect ratios, cost-effectiveness, and scalable production. In this study, advanced laser manufacturing is used to drill porous silicon (Si) templates, successfully demolding microcilia with a high aspect ratio (exceeding 9). By integrating silicon dioxide (SiO₂) nanoparticles, a superhydrophobic surface is achieved with a hierarchical micro-nano structure. The experiments demonstrated that these structured microcilia not only exhibit remarkable durability but also maintain long-term superhydrophobicity. Furthermore, by blending with magnetic iron (II, III) oxide (Fe₃O₄) nanoparticles, superhydrophobic magnetic microcilia arrays (SMMA) are developed, enabling droplet transportation on their surface controlled by an external magnetic field. These artificial microcilia have potential applications in biomedical devices, self-cleaning anti-fouling surfaces, and human sensing technologies.