When used for disease testing, a centrifuge separates blood components and makes pathogens easier to detect. A typical centrifuge spins fluid samples inside an electric-powered, rotating drum. Inspired by a whirligig toy, Stanford University bioengineers have developed an inexpensive, human-powered blood centrifuge that will enable precise diagnosis and treatment of diseases like malaria, African sleeping sickness, and tuberculosis in the poor, off-the-grid regions where these diseases are most prevalent. Built from 20 cents of paper, twine, and plastic, this “paperfuge” can spin at speeds of 125,000 rpm and exert centrifugal forces of 30,000 Gs. It separates blood into its individual components in only 1.5 minutes.