When you get into the third world areas where many doctors operate with access to the sort of facilities we have in the US and other countries, it can be hard to get the gear you need. Doctors working in the wilds of Africa for instance won’t have access to a microscope to use in diagnosing someone that is ill.
Some researchers have come up with a cheap and simple way to turn an iPhone into a diagnostic tool in the form of a microscope. The iPhone has a small 1mm diameter ball lens embedded in a rubber disc that is taped to the iPhone lens. The lens and camera sensor for the iPhone together can take photos of things up to a scant 1.5 microns.
Once snapped the photos are stitched together with software and can then be emailed to another doctor worlds away for diagnosis. The lens used in the prototype camera cost under $40. The lens can image blood cells with enough resolution for identification.