A newly developed self-contained miniature fluorescence microscope small and robust enough to be carried on the head of a mouse could be used as a portable field instrument or arranged in arrays of multiple microscopes for parallel imaging of biological samples. A tiny fluorescence microscope developed at Stanford University could offer more portable studies of a range of biological topics. (Credit: Dan Stober, Stanford News Service) Much effort has been made toward the creation of portable low-cost microscopes for applications ranging from neuroscience to field diagnostics, but such systems have had considerable limitations. Mark Schnitzer of Stanford University and his colleagues describe in a recent edition of Nature Methods a widely applicable fluorescence microscope that weighs only 1.9 g and is built using mass-producible parts that include everything from the light source to the optics to the image sensor. The instruments’ many potential uses were demonstrated by imaging blood flow and neuronal signaling in a freely behaving mouse, by parallel imaging of zebra fish, and by the counting of cultured cells and bacteria. Schnitzer and his team believe the design of the system will permit straightforward low-cost mass production. Although there is still room for improvement, the performance approaches that of standard full-size fluorescence microscopes. See also: “Deep Brain Imaged for Months at a Time” For more information, visit: www.stanford.edu