Ultrasound imaging is one of the most widely used diagnostic tools in modern medicine. Behind its non-invasive magic lies a class of materials known as piezoelectric single crystals, which can convert electrical signals into mechanical vibrations and vice versa. Now, in a world-first, a research team from Kumamoto University has successfully visualized how tiny structures inside one of these crystals respond to electric fields in real time—shedding light on the dynamics of nanostructure in materials used in ultrasound probes.