When Manu Prakash pulls his little creation of paper and string from his pocket, no one probably gives it a second glance. Either that, or they think it’s odd for this man to be carrying such an outdated toy.
But no, it’s not just a toy. And its worth definitely goes beyond the 20 cents it cost to make it. Because this Paperfuge, as dubbed by Prakash, does what its namesake can--but better.
Better because unlike a normal centrifuge, the Paperfuge does not require electricity; it does not cost as much money; and it does not take up as much space. Moreover, the Paperfuge can spin biological samples at 125,000 rpm, effective enough to separate plasma from a blood sample in 90 seconds. A procedure that when done with a StatSpin MP centrifuge (a commercial centrifuge), will take up to 2 minutes to finish at only 15,800 rpm.
You can’t fit all 5.5 pounds of the StatSpin in your pocket, either.
A Road Paved With Similar Intentions
Clearly, the world isn’t as generally satisfied with the run-of-the-mill centrifuge anymore. Because Prakash’s Stanford lab isn’t the first lab to attempt to find an alternative for the bulky spinners.
Researchers in George Whitesides’ lab at Harvard repurposed an egg beater in 2008. They got as far as 1,200 rpm. In 2011, researchers out of Rebecca-Richards Kortum’s lab at Rice University tried it with an OXO salad spinner. They managed to hit 600 rpm.
Compared to the Paperfuge, the previous attempts were considerably bigger, more expensive, and consequently less effective. “We wanted a much bigger jump,” Prakash says. “For us, it wasn’t about finding the first thing that worked. It was about pushing the limit. We wanted an absolute solution.”
No Play Would've Meant No Paperfuge
His team started with tops, but they could never spin fast enough. Next, they moved on to yo-yos. And though they may have found some success, Prakash thought the learning curve was way too steep. You have to learn how to throw a yo-yo. And the actual throwing offers very little in terms of consistency.
Saad Bhamla, a postdoc in Prakash’s lab, remembered a toy from his childhood in India: a whirligig. It’s a toy that’s been around for thousands of years, a disc suspended, spun on a loop of string tugged on by your fingers. The more you do it, the faster it goes, spinning in one direction as you pull then spinning in another as you ease up.
“It’s a simple design, so one night, I made one myself.” Bhamla says. A string and a button was all it took. And when he analyzed the footage of his test runs later, he discovered that the button spun between 10,000-15,000 rpm. That was when he knew that this was it. This was the toy.
The Toy That Changed The Game
The Paperfuge captured with a high-speed camera. (c) Prakash et al.
The team studied the ins and outs of the whirligig, up close and repeatedly. They documented every pull of the string, the winding and unwinding of the coil, and every flap of the disc they were using. The disc evolved from one small to big, from one type of material to the next: wood, plastic, acrylics.
In the end they still wound up with the same synthetic paper that Prakash used for his Foldscope, “It has polymer films on both front and back that make it waterproof, and it’s incredibly strong, as well,” Prakash says.
The Foldscope is the origami inspired folding microscope that bore into Prakash’s mind that access to affordable yet powerful equipment could cause profound breakthroughs in science and medicine all over. Bhamla and Prakash’s recent trip to Madagascar to test the Paperfuge in the field proved this philosophy to be correct.
One of the diagnostic technicians they met, a woman who specializes in malaria, had overflowing appreciation for the tool. She said she’d been hoping for something like the Paperfuge for years.
She said that before, they had to transport big centrifuges to remote villages along with the huge generators needed to power them. But now, all she needed was herself and a spacious pocket. And that changes everything.