Lessons in Low-Cost Healthcare from a Paper Centrifuge

What costs a fraction of a dollar, reaches speeds of 125,000 revolutions per minute (RPM), and may usher in a new era of affordable healthcare in developing countries?

What costs a fraction of a dollar, reaches speeds of 125,000 revolutions per minute (RPM), and may usher in a new era of affordable healthcare in developing countries?

The answer is a centrifuge made of paper and string, based on a traditional children’s toy, and making a big splash in the world of global healthcare.

Earlier this year, a research team from Stanford University led by bioengineer Manu Prakash announced the ‘paperfuge’ as the latest innovation in a movement termed ‘frugal science’.

Prakash’s previous low-cost contributions to science include an origami microscope, capable of magnifying objects more than 2,000 times, and a tiny hand-cranked medical lab.

While the paperfuge and its predecessors are intriguing wonders in the Western world, elsewhere they are revolutionising the way diseases are diagnosed. Field tests in Madagascar, for example, have already suggested that the paperfuge can be recreated from fishing wire, paper, and wood, and used by anyone to perform simple yet life-changing medical tests.

How does it work?

The low-cost paperfuge follows the basic principles of costly and cumbersome bench centrifuges. These allow medics to test patients for infectious diseases such as malaria, HIV and tuberculosis by separating different types of cells for analysis.

Centrifuges generate centrifugal force by spinning samples of blood, urine or stool at speeds of up to 20,000 rpm, meaning that cells of different densities are spread apart. This makes it easy to identify pathogens, which will be separated from the rest of the sample.

Instead of using electricity to spin the samples, Prakash’s design relies on the nonlinear oscillations of two strings to rotate a central disc. This was inspired by the whirligig, a spinning toy that dates back to ancient China.

Constructed of two paper discs with two strands of string or fishing wire threaded through a hole in the center, the paperfuge requires only the movement of two wooden handles to spin it at up to 125,000rpm. By pulling the handles apart again and again, users can create a supercoiled structure, releasing enough constant kinetic energy to keep the discs spinning.

Researchers used Velcro to fasten tiny samples of blood between the disks, before spinning them at top speeds. In controlled tests, this process separated malaria cells from infected blood after a mere 15 minutes of hand-spinning.

What does it mean for developing countries?

“There are a billion people on this planet who live with no electricity, no infrastructure, no roads, and they have the same kind of health care needs that you and I have,” said Prakash about the need for a solution like the paperfuge.

Indeed, in developing countries where infectious diseases such as malaria and HIV are more prevalent, the need for readily accessible diagnostic technology is more urgent than ever. However, these are the very same areas where lack of funding and remote communities make access to traditional centrifuges next to impossible.

A diagnostic technician in Madagascar, where the paperfuge was first tested, told the Stanford team that diagnosing such diseases had previously required Jeeps to transport centrifuges to villages, and generators to power them. Now, however, she can look forward to a future where every village has an affordable and easy-to-use centrifuge of its own.

What challenges remain?

While the paperfuge looks like a godsend for rural communities, challenges remain when it comes to safely and successfully implementing it into routine clinical work.

Researchers are currently looking into ways to safely transfer blood samples from the tiny tubes they’re spun in onto a plastic or paper slip for subsequent analysis.

Furthermore, a specific protocol for proper use of the device needs to be written and approved before it can be used widely. A key concern is the room for human error - for example, can all users be relied on to spin samples for the full 15 minutes necessary to separate pathogens?

When it comes to offering a cost-efficient method of diagnosis to developing communities, it may seem like anything is better than nothing. However, in order to ensure that standards of external validity are met, the paperfuge will undergo rigorous testing in rural Madagascar before any further steps are taken.

What can we learn?

Perhaps the most fascinating aspect of the paperfuge is the way in which it breaks medical paradigms, redesigning a key component of diagnosis from the ground up with cost-effectiveness and ease of use at its core.

While the paperfuge itself may still have a long way to go before it’s used on a global scale, the type of thinking that led to it is only just taking off.

Thanks to this particular advance, the concept of frugal science is now being discussed across the globe, with experts discussing how devices made from everyday materials can be used to improve healthcare in some of our world’s most economically deprived areas.

The movement’s drive toward better scientific education in developing countries is of particular interest to Prakash, who envisions young people using tools such as the paperfuge and the foldoscope to improve themselves and their communities.

It is fitting, then, that the design for this remarkable piece of technology is inspired by an ancient plaything. As Prakash explains, “The things that you make for kids to explore science are also exactly the kind of things that you need in the field because they need to be robust and they need to be highly versatile.”

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