A human-powered paper centrifuge

Testing human blood for tropical diseases like malaria can be difficult in some parts of the world. Centrifuges used to separate the blood for testing are expensive and require electricity. Researchers from Stanford have developed an ingenious human-powered centrifuge made of paper and string inspired by a children’s toy invented 5000 years ago (paging Steven Johnson, Steven Johnson to the courtesy desk please).

In a global-health context, commercial centrifuges are expensive, bulky and electricity-powered, and thus constitute a critical bottleneck in the development of decentralized, battery-free point-of-care diagnostic devices. Here, we report an ultralow-cost (20 cents), lightweight (2 g), human-powered paper centrifuge (which we name ‘paperfuge’) designed on the basis of a theoretical model inspired by the fundamental mechanics of an ancient whirligig (or buzzer toy; 3,300 BC). The paperfuge achieves speeds of 125,000 r.p.m. (and equivalent centrifugal forces of 30,000 g), with theoretical limits predicting 1,000,000 r.p.m. We demonstrate that the paperfuge can separate pure plasma from whole blood in less than 1.5 min, and isolate malaria parasites in 15 min.

A million rpm from paper and string…that’s incredible. (via gizmodo)

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