Blood borne tropical diseases like malaria, African sleeping sickness, schistosomiasis, and Chagas seriously harm millions of people. Early detection would help in treating them but traditional microscopes are expensive and scarce and not easily stored and maintained in remote areas.

But one Stanford University professor has developed an almost indestructible disposable microscope that can be easily transported and assembled and costs around 50 cents.

The Foldscope can be assembled in minutes, includes no mechanical moving parts, packs in a flat configuration, is extremely rugged and can be incinerated after use to safely dispose of infectious biological samples. With minor design modifications, it can be used for bright-field, multi-fluorescence or projection microscopy.

One of the unique design features of the microscope is the use of inexpensive spherical lenses rather than the precision-ground curved glass lenses used in traditional microscopes. These poppy-seed-sized lenses were originally mass produced in various sizes as an abrasive grit that was thrown into industrial tumblers to knock the rough edges off metal parts. In the simplest configuration of the Foldscope, one 17-cent lens is press-fit into a small hole in the center of the slide-mounting platform. Some of his more sophisticated versions use multiple lenses and filters.

To use a Foldscope, a sample is mounted on a microscope slide and wedged between the paper layers of the microscope. With a thumb and forefinger grasping each end of the layered paper strip, a user holds the micro-lens close enough to one eye that eyebrows touch the paper. Focusing and locating a target object are achieved by flexing and sliding the paper platform with the thumb and fingers.

Because of the unique optical physics of a spherical lens held close to the eye, samples can be magnified up to 2,000 times.

It looks like an extremely useful device.