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 Spinning toy reinvented as low-tech centrifuge

Growing up in India, Manu Prakash entertained himself with a bottle cap that spun around on two strings that he tugged with his fingers. As a physical biologist at Stanford University in California, he is now transforming that simple toy, called a whirligig, into a cheap tool to help diagnose diseases such as malaria.

Prakash started this project, the results of which are published on 10 January in Nature Biomedical Engineering1, after a research trip to Uganda in 2013. While visiting health-care clinics, he noticed that most lacked a working centrifuge — or the electricity to power one — and could not separate blood samples to perform basic disease diagnostics.

“One clinic used its broken centrifuge as a doorstop,” says Prakash, a 2016 MacArthur ‘genius grant’ winner who has also invented a foldable paper microscope2. “When we got back from Africa we asked ourselves, ‘Can we do centrifugation with no electricity, using only human power?’

It’s hard to see in the photos, but this patient has Babesia microti (the purple inclusions in the red cell).

Babesia microti is a malaria-like parasite that infects red blood cells. The parasite is transmitted by ticks.