SOPAT GmbH 1 article published in JoVE Bioengineering In Situ Microscopy for Real-time Determination of Single-cell Morphology in Bioprocesses Anna Maria Marbà-Ardébol1, Joern Emmerich2, Michael Muthig2, Peter Neubauer1, Stefan Junne1 1Chair of Bioprocess Engineering, Department of Biotechnology, Technische Universität Berlin, 2SOPAT GmbH A photo-optical in situ microscopy device was developed to monitor the size of single cells directly in the cell suspension. The real-time measurement is conducted by coupling the photo-optical sterilizable probe to an automated image analysis. Morphological changes appear with dependence on the growth state and cultivation conditions.