Now Manu Prakash, a bioengineer at Stanford University, has designed a microscope made almost entirely of paper, which is so cheap that the question of servicing it goes out of the window. Individual Foldscopes are printed on A4 sheets of paper (ideally polymer-coated for durability). A pattern of perforations on the sheet marks out the ’scope’s components, which are colour-coded in a way intended to assist the user in the task of assembly.
The Foldscope’s non-paper components, a poppy-seed-sized spherical lens made of borosilicate or corundum, a light-emitting diode (LED), a watch battery, a switch and some copper tape to complete the electrical circuit, are pressed into or bonded onto the paper. (The lenses are actually bits of abrasive grit intended to roll around in tumblers that smooth-off metal parts.) A high-resolution version of this costs less than a dollar, and offers a magnification of up to 2,100 times and a resolving power of less than a micron. A lower-spec version (up to 400x magnification) costs less than 60 cents."
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