Researchers from the University of Adelaide and the University of Stuttgart have developed an ultrathin endoscope small enough to scan images from inside the blood vessels of mice. In humans, the scope will help scientists better understand causes of heart attack and disease progression and, subsequently, methods for treatment and prevention. Ultrathin 3D-printed endoscope imaging an artery. Courtesy of Simon Thiele and Jiawen Li. Using 3D microprinting, researchers printed high-quality, complex camera lenses too small to see with the naked eye. To build the device, they then printed a lens on the end of an optical fiber no thicker than a human hair. Researchers who fabricated the lens — including Simon Thiele, group leader of optical design and simulation at the University of Stuttgart — said the imaging device is the smallest endoscope in existence. With a protective casing, the device is less than 0.5 mm in length. Miniaturized endoscopes allow doctors to monitor, from inside the blood vessels, the development and formation of plaques that build up in vessel walls, helping them better understand a major contributor to heart disease. Jiawen Li, Heart Foundation postdoctoral fellow at the University of Adelaide’s Institute for Photonics and Advanced Sensing, co-authored the study introducing the endoscope. Preclinical and clinical diagnostics, she said, increasingly rely on visualizing and imaging the structure of blood vessels, including from inside the structures themselves. The research was published in Light: Science & Applications (www.doi.org/10.1038/s41377-020-00365-w).