PhotoBiotics Ltd View Institution's Website 1 article published in JoVE Bioengineering Fluorescence Lifetime Imaging of Molecular Rotors in Living Cells Klaus Suhling1, James A. Levitt1, Pei- Hua Chung1, Marina. K. Kuimova2, Gokhan Yahioglu3 1Department of Physics, King's College London, 2Department of Chemistry, Imperial College London, 3PhotoBiotics Ltd Fluorescence Lifetime Imaging (FLIM) has emerged as a key technique to image the environment and interaction of specific proteins and dyes in living cells. FLIM of fluorescent molecular rotors allows mapping of viscosity in living cells.