Do you remember ever playing with a whirligig when you were a kid? The simple toy, which dates back thousands of years, is made using two looped ends of thread and a small button. When put together, pulling the strings makes the button spin very quickly.
While perhaps not up to the toy standards of today’s youth, Stanford researchers have taken inspiration from it to create a handheld device that can help doctors quickly diagnose and treat dangerous diseases in low socioeconomic regions.
By outfitting a whirligig with small capillaries that can hold blood, users can pull the threads and separate individual blood components for analysis. So, basically, this small device can effectively do the job of a centrifuge. The catch? While centrifuge machines can cost between $1,000 and $5,000, the “paperfuge” costs less than a dollar to produce.
“This is a tool that requires no electricity, no infrastructure -- you can carry them around in your pockets for a price point of 20 cents,” said Manu Prakash, Assistant Professor of Bioengineering at Stanford University.
Much-needed for off-the-grid regions
The paperfuge is capable of spinning at 125,000 rpm and creating 30,000 Gs in centrifugal force. Prakash believes that it is the fastest spinning object that is driven solely by human power. But while the mechanical implications are impressive, what it may be able to do for low-income areas is astounding.
Having a centrifuge is essential for detecting many dangerous diseases, ranging from malaria and HIV to tuberculosis and African sleeping sickness. Unfortunately, many off-the-grid regions of the world where these diseases are most prominent do not have access to them because they are so expensive. The researchers realized this problem and went to work trying to create a suitable replacement.
“There are more than a billion people around the world who have no infrastructure, no roads, no electricity. I realized that if we wanted to solve a critical problem like malaria diagnosis, we needed to design a human-powered centrifuge that costs less than a cup of coffee,” said Prakash.
Working with fellow researcher Saad Bhamla, Prakash began coming up with ideas on how such a device could be made. The stroke of inspiration may have happened, however, when the duo least expected it.
“One night I was playing with a button and string, and out of curiosity, I set up a high-speed camera to see how fast a button whirligig would spin. I couldn’t believe my eyes,” said Bhamla, who recorded rpms between 10,000 and 15,000.
After examining the math behind the simple toy and creating a prototype, Prakash and Bhamla matched their paperfuge against real centrifuge machines. The results were very positive, and the pair determined that their device could separate blood in as little as a minute and half, though separating parasites in malaria-infected blood could take up to 15 minutes.