The centrifuge is a special device that’s used to spin a blood sample in rapid motion to separate different blood cell types from each other. It can also be used to analyze urine and stool samples. It’s an indispensable tool for medical diagnostics. And yet many hospitals, especially in developing countries, don’t own one because it is quite expensive. Besides, it needs electricity to run, and not all medical facilities and clinics in remote areas necessarily have access to electric power. Which means even if they had one, they won’t be able to use it.
Biophysicist Manu Prakash witnessed this reality firsthand when he visited a clinic in Uganda back in 2013. They had a centrifuge, but instead of serving its diagnostic purpose, it was functioning as a mere doorstopper. Why? Because there was no electricity to make it run.
It was this fateful incident that started the work on what we now know as the paperfuge — a hand-powered device that has the potential to revolutionize the world of health care by reducing the cost of blood analysis and disease diagnosis in remote locations where lab equipment is hard to find. It was created by Prakash in collaboration with a team of researchers at Stanford University, and was inspired by the “fundamental mechanics of an ancient whirligig”. A whirligig is a toy that’s made of a disc that spins when the strings that pass through its center are pulled.
The paperfuge is built using the simplest of materials — paper discs fortified with polymer film, some string, and PVC pipe or wood. To use the device, blood samples are attached to the center disc using tiny straws, then one simply has to twist the string and tug on it to make it spin and cause cells to separate, exactly like how a typical centrifuge works.
A prototype of the device was brought to Madagascar for a test run. And it worked like it was supposed to — spinning at the rate of up to 125,000 revolutions per minute, only taking 90 seconds to separate pure plasma (the liquid part of the blood) from the other cells within, and another 15 minutes to isolate malaria parasites if present.
So far, the team has built over a thousand of their paperfuges. They’ve even used a 3D desktop printer to print over 100 units in one day. They have proven without question that the current version of their paperfuge is capable of detecting malaria parasites. They’re now working on other variations so their low-cost device can be used to diagnose other diseases.
Details about the paperfuge have been published in the journal Nature Biomedical Engineering.
Prior to this paperfuge project, Prakash, who is considered a pioneer in frugal science — a field that focuses on the development of inexpensive tools that do important work — has other accomplishments under his belt, including a microfluidic chemistry lab that costs less than $5, and a microscope called Foldscope which was made of materials worth merely $0.55.