A Foldscope is an optical microscope that can be assembled from simple components, including a sheet of paper and a lens. It was created by Manu Prakash and designed to cost less than one USD to build. It is a part of the "frugal science" movement which aims to make cheap and easy tools available for scientific use in the developing world. History The basic principle of using a small spherical lens held close to the eye dates back to the time of Antonie van Leeuwenhoek (1632–1723), who was the first to see single-celled organisms using such a lens held in a device of his own design. The Foldscope was developed by a team led by Manu Prakash, an assistant professor of bioengineering at the Stanford School of Medicine. The project was funded by several organisations including the Bill & Melinda Gates Foundation, which gave a grant of US$100,000 for research in November 2012. The idea for creating a low-cost microscope came to Prakash in 2011 while he was at a field station in Thailand. He remarked that the station had a very expensive microscope but that everyone was afraid to use it because it was fragile and worth more than most people's salaries. He wanted to create an affordable microscope that would be versatile and sturdy enough to work in field conditions. He also wanted to create a device that people felt they had ownership of, which is part of the reason the Foldscope comes in a kit to be assembled. He developed the first prototype in 2014. Details A Foldscope is an optical microscope that can be assembled from a punched sheet of cardstock, a spherical glass lens, a light emitting diode (LED) and a diffuser panel, along with a watch battery that powers the LED. Once assembled, the Foldscope is about the size of a bookmark. The Foldscope weighs 8 grams and comes in a kit with a lens that magnifies 140X. The kit also includes magnets that can be stuck onto the Foldscope to attach it to a smartphone, allowing the user to take pictures of the magnification. The magnification power is enough to enable the spotting of organisms such as Leishmania donovani and Escherichia coli, as well as malarial parasites. A Foldscope can be printed on a standard A4 sheet of paper and assembled in seven minutes. Prakash claims that the Foldscope can survive harsh