Stanford Engineers Develop Low-Cost Hand Powered Centrifuge

Manu Prakash has developed a paper centrifuge, inspired by a buzzer whirligig toy.

Manu Prakash is driven by the fact that around a billion people in the world don’t have access to clean water, healthcare, and electricity. This drives him to make the simplest possible tools for developing nations to use. Prakash first saw a centrifuge being used as a doorstop in Uganda. The equipment was donated to the lab but there wasn’t electricity available so the tool went unused. This led him to think of ways to build a low-investment, low-cost centrifuge.

Prakash worked with postdoctoral research fellow Saad Bhamla to develop a new centrifuge idea, and the team was inspired by spinning toys. Using a high speed camera Bhamla found that a button on a string could spin up to 15,000 rotations per minute. To prove the concept a larger whirligig device was built and after mounting a blood sample to the device the blood separated into layers. The current device has been measured at speeds up to 125,000 rpm with an equivalent centrifugal force of 30,000g.

Brandon Benson, Chew Chai, Georgios Katsikis, Aanchal Johri, Prakash and Bhamla are authors of the article Hand-powered ultralow-cost paper centrifuge, published as part of Nature’s Biomedical Engineering section on January 10. The paper has an incredible Supplementary Information section showing the team’s research and theory of the buzzer whirligig, with special sections devoted to input torque, drag torque, twisting torque, and the relative centrifugal forces. Plastic, polydimethylsiloxane, and 3D printed materials were also investigated during the development period. Early testing has been done in Madagascar for malaria diagnostics, working with PIVOT and Institut Pasteur to train healthcare workers in the use of the tool. Demonstrations show that plasma is separated from blood in less than 1.5 minutes, and malaria parasites isolated in 15 minutes.

This is another entry in Prakash and the Stanford Center for Innovation in Global Health’s toolbox of redesigned medical devices.  We’ve previously covered his paper telescope in 2014 and its new initiative last year. The goal of bringing low-cost and technologically sound diagnostic equipment to resource poor nations is amazing, using principles of engineering to make the world a better place. 

(Images courtesy of and Stanford University Communications)