## Friday, January 20, 2017

### Manu Prakash and the Paperfuge

Three years ago I wrote a blog post about a crazy Stanford engineer, Manu Prakash, who developed a paper origami microscope called “foldscope” costing less than a dollar. LESS THAN A DOLLAR!

Well, he’s done it again. Now his team has invented a hand-held, lightweight centrifuge called “paperfuge” costing under 20 cents. UNDER 20 CENTS!!!

I’m thinking of buying one if I can scrape up the cash. Buddy, can you spare a dime?

Excuse me if you have already heard about paperfuge on social media; its been popping up a lot on Facebook and Twitter. I hate to jump on a bandwagon, but this is so amazing I have to tell you about it.

The physics of the centrifuge is described in a series of homework problems in the first chapter of Intermediate Physics for Medicine and Biology. Please, don’t think that topics relegated to the end-of-the-chapter exercises are less important than subjects discussed in the text. Sometimes key issues such as the centrifuge lend themselves to the homework, and you learn more by actively doing the problems then by passively reading prose (even mine!).

But let me get back to Prakash. His team recently published a paper in Nature Biomedical Engineering titled “Hand-Powered Ultralow-Cost Paper Centrifuge” (read it online here). The abstract says:
In a global-health context, commercial centrifuges are expensive, bulky and electricity-powered, and thus constitute a critical bottleneck in the development of decentralized, battery-free point-of-care diagnostic devices. Here, we report an ultralow-cost (20 cents), lightweight (2 g), human-powered paper centrifuge (which we name “paperfuge”) designed on the basis of a theoretical model inspired by the fundamental mechanics of an ancient whirligig (or buzzer toy; 3,300 BC). The paperfuge achieves speeds of 125,000 r.p.m. (and equivalent centrifugal forces of 30,000 g), with theoretical limits predicting 1,000,000 r.p.m. We demonstrate that the paperfuge can separate pure plasma from whole blood in less than 1.5 min, and isolate malaria parasites in 15 min. We also show that paperfuge-like centrifugal microfluidic devices can be made of polydimethylsiloxane, plastic and 3D-printed polymeric materials. Ultracheap, power-free centrifuges should open up opportunities for point-of-care diagnostics in resource-poor settings and for applications in science education and field ecology.
I’m telling you, the paperfuge is huge. My gosh, Prakash; this whirligig may make it big. I’m a fan of can-do Manu and his breakthrough; it’s a real coup.

You also might like the “News and Views” editorial that accompanies their paper. Plus, articles lauding the paperfuge are all over the internet, such as this one in PhysicsWorld and this one on the National Public Radio website.

For those of you who prefer video, check out this great clip put out by Stanford University.