MIT's Technolgy Review reports on a prototype out of Harvard that places a microfluidic device on a piece of paper the size of a pinky fingernail. George Whitesides and his group designed this chip to use paper's innate capillary action to absorb the sample, instead of relying on pumps or other power sources. "The kinds of things we're developing here are intended to be useful for screening public health in the developing world," says Whitesides.