Abstract
Oxygen is a crucial parameter for organotypic in vitro -cultures which are still performed under ambient atmosphere supplemented with 5 % CO 2 . This can lead to hyperoxia with its associated effects on signaling cascades and their effects on cellular behavior. Here, we describe a platform that enables real-time, label-free, optical oxygen (gradient) measurements in organotypic 3D-/organoid cultures thus allowing for physioxic culture and assay conditions in e. g. mito stress tests and substance testing.