Patterned slip boundaries modulate microswimmer dynamics in two-dimensional superhydrophobic microchannels

Abstract

This study investigates how patterned slip conditions on superhydrophobic microchannel walls affect the near-wall dynamics of microswimmers. Using a two-dimensional lattice Boltzmann method, we simulate the motion of neutral, puller, and pusher-type squirmers near walls with alternating no-slip and slip segments. By systematically varying the surface pattern length scale (R) and slip ratio (φ), we reveal how these parameters modulate swimmer trajectories, retention distances, and escape angles. Notably, puller and pusher microswimmers exhibit distinct wall-induced behaviors—including sliding, large-amplitude oscillations, and trapping modes—depending on the wall configuration. Our results demonstrate that the key mechanism underlying these transitions is the swimmer's transient exposure to different boundary types during its near-wall interaction. These findings provide mechanistic insights into microswimmer–wall interactions and offer theoretical guidance for designing microfluidic surfaces for controlled swimmer navigation, sorting, and trapping.