Microscopes less than two centimetres in diameter could revolutionise low-cost science and medicine in the developing world, in areas such as parasite detection for malaria diagnosis.
Devised by Changheui Yang at the US-based California Institute of Technology in Pasadena, the microscopes are robust, use sunlight as their energy source; need only a small amount of computational power and cost just US$10 each to produce.
The microscopes are so small that they do not even have lenses. The principle on which they are based is that of floaters — deposits within the lens and retina of the eyeball. The human eye registers these deposits because of the shadows they cast directly onto the retina. In Yang's microscope, the sample casts a shadow onto an array of light sensors as it floats along a fluid channel. Sensors feed this projected pattern into a computer, which then constructs an image.
"This is a way of making a [high-power] microscope that is very low cost, maybe even disposable, and that's something that we haven't had before," says Charles DiMarzio, director of the Optical Science Laboratory at Northeastern University in the United States.
Ricardio Leitão, a postdoctoral fellow at New York University School of Medicine who is compiling a toolkit to enable telemedicine in developing countries, proposed collaborating with Yang as soon as his research was published. They are now testing whether the microscope can diagnose malaria-infected red blood cells.
"Having a diagnostic tool as powerful as Yang's integrated with our hardware and 'tele' ability would be of tremendous clinical value," says Leitão.