Dr. Judy Su is Assistant Professor in Biomedical Engineering, Optical Sciences, and the BIO5 Institute at the University of Arizona. She is developing novel sensors that use light to detect extremely low concentrations of substances. She shares how the sensors are made, how they work, and how they could be used in testing for doping. Beyond their high sensitivity, the sensors deliver results rapidly, require low sample volumes, and are better suited to detecting microdosing and drugs with a short half life.