Scientists from the Californian Institute of Technology have developed a high resolution microscope which is small enough to fit on a fingertip. It uses "microfluidics" with a grid of CCD sensors -- as used in digital cameras -- to allow the liquid being analysed to be viewed in high magnification. The chip needs to be illuminated from above, but sunlight is sufficient, meaning that it could provide a useful mobile solution for medical diagnosis in developing countries, as well as anywhere else...