A team of researchers at UC Davis have come up with a super-cheap way of turning an iPhone into a microscope — useful for diagnosing diseases in areas where medical equipment is hard to come by. Inspired by the CellScope project at UC Berkeley, Sebastian Wachsmann-Hogiu decided to create something even smaller and cheaper. By taping a 1-millimeter ball lens embedded in a rubber sheet to the iPhone, he was able to boost magnification by 5x, which allows the camera to photograph blood cells. Only a small portion of each image is in focus, so they also utilize focus stacking to achieve more usable photos.
The best part is the price — each lens only costs $30-40, and would be even cheaper if mass produced.