Photogyrotactic Concentration of a Population of Swimming Microalgae Across a Porous Layer

The light environment controls the swimming of microalgae through a light-seeking and avoiding behaviour, which is known as phototaxis. In this work, we exploit phototaxis to control migration concentration populations soil microalga Chlamydomonas reinhardtii . By imaging suspension these in cuvette illuminated from above by blue light, study how changes stability demonstrate thin, porous layer at top prevents phototaxing sinking, leading up-concentration region layer. We discuss potential implications our findings for biotechnological applications natural environment.