Microbial narrow-escape is facilitated by wall interactions

Cells have evolved efficient strategies to probe their surroundings and navigate through complex environments. From metastatic spread in the body to swimming cells in porous materials, escape through narrow constrictions—a key component of any structured environment connecting isolated microdomains—is one ubiquitous and crucial aspect of cell exploration. Here, using the model microalgae Chlamydomonas reinhardtii, we combine experiments and simulations to achieve a tractable realization of the classical Brownian narrow-escape problem in the context of active confined matter. Our results differ from those expected for Brownian particles or leaking chaotic billiards and demonstrate that cell-wall interactions substantially modify escape rates and, under generic conditions, expedite spread dynamics.We acknowledge financial support from Grants No. CTM2017-83774-P and No. IED2019-000958-I (IT), Grant No. PID2019-104232GB-I00 (I.T. and M.P.) from the Spanish Ministerio de Ciencia e Innovación (MICINN), the Ramón y Cajal Program (Grant No. RYC-2018-02534; M.P.), ECOST-STSM-Request-CA17120-47203 for the COST Action (European Cooperation in Science and Technology); Grant No. RPG-2018-345 (A.A. and M.P.) from The Leverhulme Trust; and H2020 MSCA ITN PHYMOT (Grant Agreement No. 955910; I.T. and M.P.). M.S. also acknowledges A. Marin for his financial support.Peer reviewe