SoylentNews is people
SoylentNews
From the paper in Nature Biomedical Engineering:
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.
The lead inventor, Manu Prakash, is the recipient of a MacArthur "genius grant", and deservedly so. He also has an elegant portal web page on the Stanford site.
(Score: 3, Insightful) by Anonymous Coward on Friday January 13 2017, @02:32AM
Requires a fast cycle rate to get up to the required high rpm, 2Hz+. TFA says that at 10 Hz in and out will get to a million rpm peak. So your foot might be OK, but rocking chair is far too slow.
Separate question, the little straws that hold the nano-pipettes have outer ends closed with epoxy. While they haven't had any of the little plastic pipettes fly out yet, it was a little scary to not see a simple push-out test on the epoxy to see how much factor of safety they have. The paper says they are seeing 10000 (ten thousand) g -- that might be quite a bit of load for the epoxy on its own, not including the pipette pushing on the epoxy. If the pipette flies out, it's going to pierce anything soft nearby--I was quite surprised to see the video with lab tech spinning the rig in front of her body (and not off to one side).
(Score: 2) by martyb on Friday January 13 2017, @02:55AM
Fair point. I read the paper and it seems that the million rpm was more of a theoretically-calculated maximum. And those were with tidy disks on the order of 5mm diameter. The test that were actually performed, IIRC, were more in the 10k-15k rpm range.
Still I will grant you that 2Hz is a wee bit fast for a rocking chair. =)
I'm too tired at the moment to fully flesh out the idea of it, but something with a stepped up gear ratio could easily handle that, with admittedly much greater complexity. Or, go back to the stirrups on strings idea I also postulated.
Agree entirely. The forces must be tremendous! I have heard of CDs actually exploding because of a slight defect causing a delamination at high speed. Also, there were problems with some kinetic storage systems basically exploding by the huge forces in effect at the circumference.
Wit is intellect, dancing.
(Score: 3, Interesting) by Reziac on Friday January 13 2017, @05:03AM
My old cow veterinarian, who could not justify spending a couple grand on a test-tube centrifuge, used cheap simple tech instead:
Place test tubes in bucket (pad with rags as needed)
Tie three feet of rope to bucket handle and knot the end of the rope
Hand this apparatus to the next client who comes in the door
Instruct them to go out to the parking lot and whirl it around their head for ten minutes
Voila, perfectly centrifuged samples at zero cost.
And there is no Alkibiades to come back and save us from ourselves.
(Score: 3, Funny) by rondon on Friday January 13 2017, @02:05PM
The first time I read your post, I thought you were calling your veterinarian fat. I'm still not sure if you are, or aren't, but I chuckled either way because the confusion is funny to me.
(Score: 2) by Reziac on Friday January 13 2017, @02:41PM
LOL! Yeah, I see how if you're not familiar with the shorthand "cow vet" ... well, the resulting picture leaves a lot to be desired, tho it may reassure the cows :D
And there is no Alkibiades to come back and save us from ourselves.