Lighting Up Heart Cells with Tiny Lasers May 11, 2021• Physics 14, 71 A new microscopy technique that uses micrometer-sized lasers can track beating-induced changes in a heart cell’s refractive index. M. Schubert/University of St Andrews Micrometer-sized lasers placed inside heart cells can track the beating of these dynamics systems. M. Schubert/University of St Andrews Micrometer-sized lasers placed inside heart cells can track the beating of these dynamics systems.× No easy method exists for imaging single cells inside live animals. Marcel Schubert of the University of St Andrews, UK, hopes his newly demonstrated technique could change that. In a talk at the Optical Society's Biophotonics Conference last month, Schubert discussed how he and his colleagues have tracked the beating of heart cells using micrometer- and nanometer-sized lasers placed directly inside the cells. The lasers could allow researchers to monitor the dynamics of cells deep inside live tissues.