Collaboration between Université de Bordeaux (CRPP, CNRS), ETH Zurich, and Universidad Autónoma de Madrid — led by Vivien Willems and Laura Alvarez

This work demonstrates the emergence of run-and-tumble-like dynamics in active, phase-separated giant unilamellar vesicles (GUVs) under AC electric fields. These Janus vesicles, composed of fluid lipid domains, self-propel via asymmetric electrohydrodynamic (EHD) flows. The intrinsic membrane fluidity allows dynamic transitions between ordered (run) and disordered (tumble) states, interrupting propulsion and enabling reorientation. These events induce reorientation times significantly faster than thermal diffusion. The observed dynamics deviate from classical Active Brownian Particle models and are well described by a Run-and-Tumble Particle framework. This study introduces a new class of reconfigurable soft microswimmers, mimicking bacterial navigation strategies and highlighting the role of membrane phase separation in active matter design.