  Bio-inspired materials are commonly used in the development of functional
devices. The fabrication of artificial cilia mimicking the biological functions
has emerged as a promising strategy for fluid manipulation in miniaturized
systems. In this study, we propose a different physicochemical insight for the
preparation of magnetic cilia based on the temperature-triggered reversible
assembly of coated iron oxide nanoparticles in a bio-compatible template-free
approach. The length of the prepared cilia could be tuned between 10 and 100
microns reaching aspect ratios up to 100 in a very dense array of flexible
structures with persistence lengths around 8 microns. Magnetic actuation of the
cilia revealed robust structures (over several hours of actuation) with a wide
range of bending amplitudes resulting from high susceptibility of the
filaments. The results demonstrate that the proposed strategy is an efficient
and versatile alternative for templated fabrication methods and producing cilia
with remarkable characteristics and dimensions within the template-free
approaches.
