01677nas a2200133   4500008004100000020001400041245010800055210006900163260001500232520120000247100002601447700002301473856004701496       2024                        eng d  a1572-964800aBreaking the left-right symmetry in fluttering artificial cilia that perform nonreciprocal oscillations0 aBreaking the leftright symmetry in fluttering artificial cilia t  c2024/04/063 aRecent investigations on active materials have introduced a new paradigm for soft robotics by showing that a complex response can be obtained from simple stimuli by harnessing dynamic instabilities. In particular, polyelectrolyte hydrogel filaments actuated by a constant electric field have been shown to exhibit self-sustained oscillations as a consequence of flutter instability. Owing to the nonreciprocal nature of the emerging oscillations, these artificial cilia are able to generate flows along the stimulus. Building upon these findings, in this paper we propose a design strategy to break the left-right symmetry in the generated flows, by endowing the filament with a natural curvature at the fabrication stage. We develop a mathematical model based on morphoelastic rod theory to characterize the stability of the equilibrium configurations of the filament, proving the persistence of flutter instability. We show that the emerging oscillations are nonreciprocal and generate thrust at an angle with the stimulus. The results we find at the level of the single cilium open new perspectives on the possible applications of artificial ciliary arrays in soft robotics and microfluidics.1 aBoiardi, Ariel, Surya1 aMarchello, Roberto  uhttps://doi.org/10.1007/s11012-024-01765-7