Healthcare Transformation – the 20cent Centrifuge


Frugal science for diagnosing disease.

Known as the “Paperfuge” invented by Manu Prakash, Professor of Bio-Engineering at Stanford, is like the piece of lab equipment it’s named for, the centrifuge, it can spin biological samples at thousands of revolutions per minute, by hand.

The simple solutions are often the most accessibleManu Prakash demonstrates how to use a Paperfuge, an ultra-affordable, hand-powered centrifuge made of paper and string., and therefore often the best solution. Paper and string…is pretty much it, and all for 20 cents. Innovation such as this bring the opportunity for those in areas of the planet with no electricity, no infrastructure, roads and funds available for the traditional equipment to diagnose infections such as malaria, HIV and more, very simply.

Prakash’s philosophy of “frugal science” —the idea that access to affordable yet powerful equipment can have a profound impact on science and medicine is optimised by this wonderfully simple invention.

The Paperfuge is a hand-powered centrifuge made of paper, string, and plastic that can whip biological samples in circles at up to 125,000 rpm. That’s enough to separate plasma from a blood sample (a standard diagnostic procedure) in 90 seconds.

Age old toys that have stood the test of time have influenced Manu in his innovations.


“There’s a sense of simplicity to their mechanisms that causes me to not only enjoy using them but thinking about them,” Prakash says.

His team started by experimenting with tops, but they didn’t spin fast enough or long enough to separate biological samples. The researchers tried yo-yos with some success, but the learning curve was way too steep.

The team spent the next few months studying the complexities of the whirligig system and converting them into a theoretical model. They discovered that much of the toy’s power hinges on a phenomenon called super-coiling. When the string coils beyond a certain threshold, it starts to form another coil on top of itself.  reproduce this phenomenon yourself by twisting your shoelace, or a length of telephone cord.) A supercoiled string stores more energy, which helps accelerate the disc to higher and higher rpms.

The researchers used this and other observations to simulate a wide range of whirligigs. Physical prototypes came next. They tweaked the length of the string and the radius of the disc, and tried a variety of materials, from balsa wood to acrylics. In the end, though, the group settled on the same stuff Prakash used to build his.

In the past, medical workers in the field had been transporting centrifuges to remote villages in Jeeps to haul the heavy electricity reliant equipment, now all they need, are their  pockets.

Certainly innovations such as the Paperfuge is a positive step towards healthy communities around the globe.

Tags: medicine