--- res: bibo_abstract: - Active navigation relies on effectively extracting information from the surrounding environment, and often features the tracking of gradients of a relevant signal—such as the concentration of molecules. Microfluidic networks of closed pathways pose the challenge of determining the shortest exit pathway, which involves the proper local decision-making at each bifurcating junction. Here, we focus on the basic decision faced at a T-junction by a microscopic particle, which orients among possible paths via its sensing of a diffusible substance's concentration. We study experimentally the navigation of colloidal particles following concentration gradients by diffusiophoresis. We treat the situation as a mean first passage time (MFPT) problem that unveils the important role of a separatrix in the concentration field to determine the statistics of path taking. Further, we use numerical experiments to study different strategies, including biomimetic ones such as run and tumble or Markovian chemotactic migration. The discontinuity in the MFPT at the junction makes it remarkably difficult for microscopic agents to follow the shortest path, irrespective of adopted navigation strategy. In contrast, increasing the size of the sensing agents improves the efficiency of short-path taking by harvesting information on a larger scale. It inspires the development of a run-and-whirl dynamics that takes advantage of the mathematical properties of harmonic functions to emulate particles beyond their own size.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Tanvi foaf_name: Gandhi, Tanvi foaf_surname: Gandhi - foaf_Person: foaf_givenName: Jinzi foaf_name: Mac Huang, Jinzi foaf_surname: Mac Huang - foaf_Person: foaf_givenName: Antoine foaf_name: Aubret, Antoine foaf_surname: Aubret - foaf_Person: foaf_givenName: Yaocheng foaf_name: Li, Yaocheng foaf_surname: Li - foaf_Person: foaf_givenName: Sophie foaf_name: Ramananarivo, Sophie foaf_surname: Ramananarivo - foaf_Person: foaf_givenName: Massimo foaf_name: Vergassola, Massimo foaf_surname: Vergassola - foaf_Person: foaf_givenName: Jérémie A foaf_name: Palacci, Jérémie A foaf_surname: Palacci foaf_workInfoHomepage: http://www.librecat.org/personId=8fb92548-2b22-11eb-b7c1-a3f0d08d7c7d orcid: 0000-0002-7253-9465 bibo_doi: 10.1103/physrevfluids.5.104202 bibo_issue: '10' bibo_volume: 5 dct_date: 2020^xs_gYear dct_isPartOf: - http://id.crossref.org/issn/2469-990X dct_language: eng dct_publisher: American Physical Society@ dct_title: Decision-making at a T-junction by gradient-sensing microscopic agents@ ...