While most efforts to understand the brain focus on new technologies to magnify small anatomical features, engineers at the MIT-based Center for Brains, Minds and Machines have found a way to make brains physically bigger. The technique, called expansion microscopy, uses an expandable polymer and water to swell brain tissue to about four and a half times its usual size, so that nanoscale structures once blurry appear sharp with an ordinary confocal microscope. The engineers who developed the technique say it offers the ability to image large, intact, 3D brain structures with nanoscale precision for the first time. Expansion microscopy enables researchers to resolve details down to about 70 nanometers, while 300 nanometers was the previous limit with a conventional microscope. Partially funded by the National Science Foundation, the novel process is another advance in brain imaging that brings researchers closer to illuminating the entire brain and nervous system, one of today's greatest engineering challenges.