This is a well-written and very clear paper. It covers several aspects that went unmentioned in the Gizmodo article, and highlights that although building such a device may be trivial, evaluating and studying it is not.
Some highlights: the paper covers how the device was built in detail, including information on the three safety mechanisms used to ensure the operator doesn't get exposed to infected blood (shatterproof plastic capillaries, epoxied sample holders made from drinking straws, and sealing of the capillaries inside two paper discs). It is exclusively made from low-cost materials, but it's more than just a piece of paper, handles and some string (fishing wire).
The paper also covers the physical dynamics of the "paperfuge" in great detail, analyzing its rotational dynamics and building a theoretical model of motion that agrees well with the physical observations (captured with a 6000fps high-speed camera). It also shows that the max RPM varies with disc size, with 125000 RPM for a small disc (5mm diameter). The paper even mentions that this was submitted as a Guiness World Record.
Finally it shows that the paperfuge produces sample separation results on par with electromechanical centrifuges using similar spinning time (1.5min for paperfuge, 2min for centrifuge for plasma separation), and does an analysis of the resulting blood samples.
> As usual, what you really want to do is read the paper:
An aside: If you are not reading Nature you may be missing out on a lot. I would guess the same applies to Science.
Only the back half of Nature is actual research papers, which often are indeed very slow going. The other half is science news written clearly - it's fascinating, not a chore at all - and with a level of knowledge and sophistication unmatched elsewhere (AFAIK), and most importantly it will completely change your perspective: There is a world of research and knowledge that you won't even know exists if you read the more 'popular' science press.
A little time reading Nature will save you much more time reading less informative publications.
Thanks a lot for the summary. It's so hard to look at simple things and see how difficult it is to make them a product, and even harder to see the edge cases that prevent it from being used in healthcare.
I really like that there's a comparison to commercial centrifuges, since that shows the quality of medical care isn't going down simply to be cheap. Overall it looks like a well thought out design.
If I was using this thing, I would fix one end to a solid endpoint and pull the other end so that I would not be in the line of fire if the thing exploded.
The lab behind this invention is led by Manu Prakash, a MacArthur Fellow [1] with a knack for unconventional solutions. He's the same guy who developed Foldscope, an ultra low cost microscope [2][3].
Looking at this makes me want to find a way to crowdsource basic research problems like this to try and take advantage of the ingenuity of people who would otherwise never even know that this kind of problem existed.
There are probably a lot of problems like this that involve making something incredibly cheap to be used in the developing world.
I think people would do that for free if they could know the bare minimum big picture of how their contribution would be used (ie, malaria treatment, even if you have no idea how your gadget could fit in). It could be something like "Need a device that can reach X rpms and can only be made of Y and Z and must cost less than N" and then just see what people can come up with.
I'm not sure how it would work on more complex problems but for clever solutions that rely on limited resources and simplicity I would love to see what people could come up with.
I think that if you could get the problem statement as concise as "Need a device that can reach X rpms and can only be made of Y and Z and must cost less than N" then the battle is won.
Another example of this kind of innovation that comes to mind is using freezing wax as a heat source to keep neonatal babies warm.
The problem statement for that would be something like, "neonates need to be kept at a stable temp."
For this one it might be, "We need some way to separate blood solids from liquids." But maybe even that is too close to a "solution stated as a problem after the fact."
I think that challenges like this are commonly used as exercises for undergrad design students. But I love the idea of expanding it. A version of the x-prizes that require basically no capital, just imagination.
This is slightly off-topic -- but for any kitchen nerds out there, Dave Arnold of Cooking Issues (amazing podcast[0]) and Searzall fame is doing a crowdfunding campaign[1] to build an "affordable" centrifuge for the kitchen/bar. His goal is to make it the next piece of high-end modernist cooking gear within reach of the home cook...
Not anywhere close to the $0.20 cost of this paper centrifuge, but still a pretty huge savings compared to the $6k-$10k units generally available currently.
Part of me wonders, A.) if it's possible to enrich uranium using something like this, and B.) how many man-years of hand-spinning it would take to get enough weapons-grade material that way.
Back of the envelope calculation: U-235 is a little less than 1% of naturally occurring Uranium, so supposing that you could load up 1 gram of Uranium per spin session, you'd get a maximum of 10 milligrams per session, so you'd need about 2.2 million sessions to get the requisite 22kg of U-235. Of course, you'd get nowhere near 100% efficiency out of a hand centrifuge in the first spin session, so it would probably require a cascade of several stages. If each stage gets rid of half of the U-238, then the number of spins you would need to get to 100% would asymptotically approach 2x, so we are looking at 4.4 million spin sessions. If each were to take 1 minute, we'd need about 8 years.
To be honest that seems overly optimistic, and there are probably technical details like dealing with UF6 gas that are way harder than I thought.
(happy to be corrected by a Nuclear engineer if there is one around).
I'd be suspect about the quality of the centrifuging since it is changing directions on every spin. But I haven't read the paper so maybe they have checked that.
I know that when I centrifuge something delicate, even having even a very light magnetic force brake on the centrifuge on can screw up the pellet at the bottom. Rapidly changing the g-force direction like this seems like the worst case scenario.
Wouldn't the g-force direction always be the same (away from the center) regardless of direction of spin and zero at the inflection between spin directions (normal gravity excepted)?
think remote villages where it's difficult to bring equipment in, places without electricity, etc.
[edit:]
from article:
A centrifuge is an essential tool for hospitals and labs across the world. Trouble is, centrifuges are expensive, bulky, and require electricity. In poor regions where tropical diseases flourish, these instruments can be hard to come by, thus limiting the ability of point-of-care healthcare workers to do their work.
[...]
The device, dubbed the “paperfuge,” can reach spinning speeds of 125,000 revolutions per minute (RPM), and exert centrifugal forces equivalent to 30,000 g’s. It’s roughly a hundred times faster than previous non-electrical efforts, and it’s considered the fastest rotational speed ever recorded for a human-powered device.
In the environments this would be used Labor is cheaper than and probably more available than electric power. This could also be built on site rather than trucked in, all you need is the knowledge of how to build it. In some instances, this kind of tool may be the only way to meaningfully accomplish testing.
While they're not that hard to build, the lab ones tend to be very heavy and not able to survive being carried around and dropped. The centrifuge they describe can be easily transported, is durable, and easy to fix. It's a great idea to be able to provide field medics with a tool like this in difficult environments where a lab grade device would be impractical.
Motors need power, not having (much) power at hand is often one of the first problems helpers in such situation have, so something which doesn't need power is a huge boon.
whats next? a fake life size cut out image of a doctor with a smartphone attached to it for a speaker?
its sad that people have to die because they don't have access to the technology that's not that expensive and readily available in the "developed countries".
And now we have to come up with some pathetic paper gizmos to justify our actions? Are we really that developed? Seems to me that we are going backwards...
I'm not really sure what you are trying to say here. If you have a better solution to centrifuge availability than a 20c one made out of paper, please enlighten us.
"Expensive" is relative, and the technology has extra costs outside of itself that have been paid in some parts of the world, but not in others. In a part of the world where electricity may as well be unobtainium, that heavy, carefully-calibrated, $1000 centrifuge isn't much better than the scrap value of the metal it's made from (while still being obscenely, prohibitively expensive for the people it would help).
> justify our actions
Who's talking about justification, besides you? There isn't anything to justify.
> Are we really that developed?
We've got shinier toys, if you want to call that "developed". We haven't improved upon the human race itself, if that's what you mean. Humans are naturally selfish and tribal. Society shifts tribal boundaries, and social structures like government can force selfishness into a longer-term view, but that's about all.
Walk into any modern hospital central lab today, look at the life saving technology thats available to us and ask yourself why we still have not figured out how to give other people access to this?
I don't know why it would be any more dangerous than a typical centrifuge. Samples are in a vial, and that vial is what is responsible for containing the sample while you spin the samples. Having been around conventional centrifuges that have been destroyed due to improper balance, I assure you that any way you can imagine infected blood being distributed by the paper model would be 10x worse with a normal centrifuge. At least with this method, the motor has a brain and will stop as soon as things start going south.
A lot of centrifuges are just controlled by a potentiometer. You couldn't pay me enough to to get close enough to turn one of those off while it is self-destructing. The amount of energy involved is enormous. Someone blew up a (rather inexpensive) medical centrifuge at my school when they balanced some non-water liquid with water. It was a huge mess. Centrifuges are basically designed to contain the most dangerous bits when they explode. They don't keep your error from spraying all over the room.
Why not? The videos show the devices being operated with one handle fixed against a wall/door. In that situation, nothing flying off the disc will go towards the operator. You could also enclosing it in a box or operate it inside a hole in the ground.
[+] [-] nneonneo|9 years ago|reply
This is a well-written and very clear paper. It covers several aspects that went unmentioned in the Gizmodo article, and highlights that although building such a device may be trivial, evaluating and studying it is not.
Some highlights: the paper covers how the device was built in detail, including information on the three safety mechanisms used to ensure the operator doesn't get exposed to infected blood (shatterproof plastic capillaries, epoxied sample holders made from drinking straws, and sealing of the capillaries inside two paper discs). It is exclusively made from low-cost materials, but it's more than just a piece of paper, handles and some string (fishing wire).
The paper also covers the physical dynamics of the "paperfuge" in great detail, analyzing its rotational dynamics and building a theoretical model of motion that agrees well with the physical observations (captured with a 6000fps high-speed camera). It also shows that the max RPM varies with disc size, with 125000 RPM for a small disc (5mm diameter). The paper even mentions that this was submitted as a Guiness World Record.
Finally it shows that the paperfuge produces sample separation results on par with electromechanical centrifuges using similar spinning time (1.5min for paperfuge, 2min for centrifuge for plasma separation), and does an analysis of the resulting blood samples.
[+] [-] hackuser|9 years ago|reply
An aside: If you are not reading Nature you may be missing out on a lot. I would guess the same applies to Science.
Only the back half of Nature is actual research papers, which often are indeed very slow going. The other half is science news written clearly - it's fascinating, not a chore at all - and with a level of knowledge and sophistication unmatched elsewhere (AFAIK), and most importantly it will completely change your perspective: There is a world of research and knowledge that you won't even know exists if you read the more 'popular' science press.
A little time reading Nature will save you much more time reading less informative publications.
[+] [-] HCIdivision17|9 years ago|reply
I really like that there's a comparison to commercial centrifuges, since that shows the quality of medical care isn't going down simply to be cheap. Overall it looks like a well thought out design.
[+] [-] tbabb|9 years ago|reply
On top of that, the g-force would be
...giving 87,000 gees?!I start to wonder if general relativity effects (frame-dragging?) start to become noticeable at that acceleration.
[+] [-] csours|9 years ago|reply
[+] [-] onchance|9 years ago|reply
[1]: https://www.macfound.org/fellows/965/
[2]: https://en.wikipedia.org/wiki/Foldscope
[3]: https://www.ted.com/talks/manu_prakash_a_50_cent_microscope_...
[+] [-] agumonkey|9 years ago|reply
[+] [-] okreallywtf|9 years ago|reply
There are probably a lot of problems like this that involve making something incredibly cheap to be used in the developing world.
I think people would do that for free if they could know the bare minimum big picture of how their contribution would be used (ie, malaria treatment, even if you have no idea how your gadget could fit in). It could be something like "Need a device that can reach X rpms and can only be made of Y and Z and must cost less than N" and then just see what people can come up with.
I'm not sure how it would work on more complex problems but for clever solutions that rely on limited resources and simplicity I would love to see what people could come up with.
[+] [-] tdaltonc|9 years ago|reply
Another example of this kind of innovation that comes to mind is using freezing wax as a heat source to keep neonatal babies warm.
http://extreme.stanford.edu/projects/embrace
The problem statement for that would be something like, "neonates need to be kept at a stable temp."
For this one it might be, "We need some way to separate blood solids from liquids." But maybe even that is too close to a "solution stated as a problem after the fact."
I think that challenges like this are commonly used as exercises for undergrad design students. But I love the idea of expanding it. A version of the x-prizes that require basically no capital, just imagination.
[+] [-] erikcw|9 years ago|reply
Not anywhere close to the $0.20 cost of this paper centrifuge, but still a pretty huge savings compared to the $6k-$10k units generally available currently.
[0] http://heritageradionetwork.org/series/cooking-issues/
[1] https://blog.modernistpantry.com/spinzall/
[+] [-] Chris2048|9 years ago|reply
See "DO I REALLY NEED TO BUY A CENTRIFUGE?" section here-> http://www.ginandluck.com/clarified-citrus-centrifuge-proces...
Also, do you have to clean this one each time (as opposed to using different bottles placed inside?
[+] [-] titzer|9 years ago|reply
Back of the envelope calculation: U-235 is a little less than 1% of naturally occurring Uranium, so supposing that you could load up 1 gram of Uranium per spin session, you'd get a maximum of 10 milligrams per session, so you'd need about 2.2 million sessions to get the requisite 22kg of U-235. Of course, you'd get nowhere near 100% efficiency out of a hand centrifuge in the first spin session, so it would probably require a cascade of several stages. If each stage gets rid of half of the U-238, then the number of spins you would need to get to 100% would asymptotically approach 2x, so we are looking at 4.4 million spin sessions. If each were to take 1 minute, we'd need about 8 years.
To be honest that seems overly optimistic, and there are probably technical details like dealing with UF6 gas that are way harder than I thought.
(happy to be corrected by a Nuclear engineer if there is one around).
[+] [-] JohnJamesRambo|9 years ago|reply
I know that when I centrifuge something delicate, even having even a very light magnetic force brake on the centrifuge on can screw up the pellet at the bottom. Rapidly changing the g-force direction like this seems like the worst case scenario.
[+] [-] tejtm|9 years ago|reply
[+] [-] emeraldd|9 years ago|reply
[+] [-] omginternets|9 years ago|reply
Seems a propos! :)
[+] [-] twiceaday|9 years ago|reply
[+] [-] feiss|9 years ago|reply
[+] [-] agumonkey|9 years ago|reply
I'd love to see how far one can go with 'simple' physics.
[+] [-] unknown|9 years ago|reply
[deleted]
[+] [-] rawnlq|9 years ago|reply
A bit curious, why is a cheap centrifuge hard to build? It seems like a pretty simple device and motors are pretty cheap.
[+] [-] mrexroad|9 years ago|reply
[edit:] from article:
A centrifuge is an essential tool for hospitals and labs across the world. Trouble is, centrifuges are expensive, bulky, and require electricity. In poor regions where tropical diseases flourish, these instruments can be hard to come by, thus limiting the ability of point-of-care healthcare workers to do their work. [...] The device, dubbed the “paperfuge,” can reach spinning speeds of 125,000 revolutions per minute (RPM), and exert centrifugal forces equivalent to 30,000 g’s. It’s roughly a hundred times faster than previous non-electrical efforts, and it’s considered the fastest rotational speed ever recorded for a human-powered device.
[+] [-] emeraldd|9 years ago|reply
[+] [-] mhb|9 years ago|reply
But presumably this could be for regions in which even those materials are difficult to obtain.
[+] [-] kognate|9 years ago|reply
[+] [-] sgift|9 years ago|reply
[+] [-] BurningFrog|9 years ago|reply
[+] [-] unknown|9 years ago|reply
[deleted]
[+] [-] unknown|9 years ago|reply
[deleted]
[+] [-] ahoka|9 years ago|reply
[+] [-] chriswarbo|9 years ago|reply
From http://catb.org/jargon/html/H/hack.html
> Originally, a quick job that produces what is needed, but not well.
See also http://catb.org/jargon/html/meaning-of-hack.html and https://stallman.org/articles/on-hacking.html
[+] [-] readhn|9 years ago|reply
its sad that people have to die because they don't have access to the technology that's not that expensive and readily available in the "developed countries".
And now we have to come up with some pathetic paper gizmos to justify our actions? Are we really that developed? Seems to me that we are going backwards...
[+] [-] hxegon|9 years ago|reply
[+] [-] witty_username|9 years ago|reply
How does this make the West go backward? The researches are helping to improve the situation.
If you are so concerned, you can go donate to charities that distribute vaccines.
[+] [-] khedoros1|9 years ago|reply
"Expensive" is relative, and the technology has extra costs outside of itself that have been paid in some parts of the world, but not in others. In a part of the world where electricity may as well be unobtainium, that heavy, carefully-calibrated, $1000 centrifuge isn't much better than the scrap value of the metal it's made from (while still being obscenely, prohibitively expensive for the people it would help).
> justify our actions
Who's talking about justification, besides you? There isn't anything to justify.
> Are we really that developed?
We've got shinier toys, if you want to call that "developed". We haven't improved upon the human race itself, if that's what you mean. Humans are naturally selfish and tribal. Society shifts tribal boundaries, and social structures like government can force selfishness into a longer-term view, but that's about all.
[+] [-] readhn|9 years ago|reply
paper centrifuge? come on...
[+] [-] juanviP|9 years ago|reply
[+] [-] grymoire1|9 years ago|reply
[+] [-] celticninja|9 years ago|reply
[+] [-] williamle8300|9 years ago|reply
[+] [-] bluetwo|9 years ago|reply
[+] [-] Declanomous|9 years ago|reply
A lot of centrifuges are just controlled by a potentiometer. You couldn't pay me enough to to get close enough to turn one of those off while it is self-destructing. The amount of energy involved is enormous. Someone blew up a (rather inexpensive) medical centrifuge at my school when they balanced some non-water liquid with water. It was a huge mess. Centrifuges are basically designed to contain the most dangerous bits when they explode. They don't keep your error from spraying all over the room.
[+] [-] nneonneo|9 years ago|reply
[+] [-] chriswarbo|9 years ago|reply
[+] [-] dv_dt|9 years ago|reply