Portable, battery-operated, fluorescence field microscope for the developing world

In many areas of the world, current methods for diagnosis of infectious diseases such as malaria and tuberculosis involve microscopic evaluation of a patient specimen. Advances in fluorescence microscopy can improve diagnostic sensitivity and reduce time and expertise necessary to interpret diagnostic results. However, modern research-grade microscopes are neither available nor appropriate for use in many settings in the developing world. To address this need, we designed, fabricated, and tested a portable, battery-powered, bright field and fluorescence inverted field microscope, optimized for infrastructural constraints of the developing world. We characterized an initial prototype constructed with rapid-prototyping techniques, which utilized low-cost, over-the-counter components such as a battery-powered LED flashlight as the light source. The microscope exhibited suitable spatial resolution (0.8 mu m) in fluorescence mode to resolve M. tuberculosis bacilli. In bright field mode, malaria parasites were resolvable at 1000x magnification. The initial prototype cost 480 USD and we estimate that the microscope can be manufactured for 230 USD. While future studies are planned to evaluate ease-of-use and reliability, our current system serves as a proof of concept that combined fluorescence and bright field microscopy is possible in a low-cost and portable system.