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Stanford University

How a Child’s Toy Inspired a Super-Cheap Paper Centrifuge

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Stanford University

Scientists at Stanford University have built a super-cheap, super-fast centrifuge out of everyday items. Their inspiration? A simple spinning toy. The team described their invention in the journal Nature Biomedical Engineering.

Biophysicist Manu Prakash is on a quest to make scientific and medical equipment cheaper and more accessible for everyone. He’s developed parasite-detecting skin patches and computers that run on drops of water. Last year, he made a splash with the introduction of the Foldoscope—an inexpensive, DIY paper microscope that users can assemble themselves. His goal is to distribute 1 million to schools worldwide by the end of 2017. 

For his next trick, Prakash turned his attention to the centrifuge, a machine that spins rapidly to separate blood samples into their component parts. Centrifuging is a basic and crucial element of conducting blood tests like the one for malaria, yet many clinics around the world either cannot afford a machine or don’t have access to the electricity required to power it. “I realized that if we wanted to solve a critical problem like malaria diagnosis,” Prakash said in a statement, “we needed to design a human-powered centrifuge that costs less than a cup of coffee.”

He brought the problem back to his lab and began brainstorming with postdoctoral research fellow Saad Bhamla. They realized that the centrifuge’s primary job is simply to spin—the same job shared by thousands of years of children’s toys. They brought in armloads of old toys and pieces and set to work playing with them.

One evening, Prakash was spinning a simple whirligig device that he’d made from a button and some string. He decided to set up a high-speed camera to see how fast the thing could go. When he checked the tape, he was amazed. The crude setup was powerful enough to get the button spinning 10,000 to 15,000 times per minute.

The next step was rigging the center disk to hold and process samples. After a few weeks of experimentation, Prakash had his prototype: a paper disk loaded with thin tubes of blood.

Not content to let it rest there, he and Bhamla recruited a team of mathematicians and asked them to optimize the new paper machine. “We realized that this is a toy that no one had thought about,” he told The Atlantic. “The physics of how it works weren’t understood, and its fundamental limits were completely unknown. So we spent six months thinking about the math, all with the goal of asking how fast it could really go.”

The answer: a staggering 125,000 revolutions per minute—which the team believes is the fastest rotational speed ever recorded for a human-powered object. (“We have submitted an application to Guinness World Records,” they note in the paper.) This “paperfuge,” as they call it, can separate liquid blood from plasma in just two minutes. In 15 minutes, it can extract malaria parasites from a drop of blood.

This exceptional speed is just part of the paperfuge’s appeal. The rest comes in its dirt-cheap construction. The final prototype is made out of waterproof paper, Velcro, drinking straws, and fishing line. It weighs less than 2 grams and can be produced for about 20 cents. And this, Prakash says, is the key: “Frugal science is about democratizing scientific tools to get them out to people around the world.”

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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Nick Briggs/Comic Relief
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What Happened to Jamie and Aurelia From Love Actually?
May 26, 2017
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Nick Briggs/Comic Relief

Fans of the romantic-comedy Love Actually recently got a bonus reunion in the form of Red Nose Day Actually, a short charity special that gave audiences a peek at where their favorite characters ended up almost 15 years later.

One of the most improbable pairings from the original film was between Jamie (Colin Firth) and Aurelia (Lúcia Moniz), who fell in love despite almost no shared vocabulary. Jamie is English, and Aurelia is Portuguese, and they know just enough of each other’s native tongues for Jamie to propose and Aurelia to accept.

A decade and a half on, they have both improved their knowledge of each other’s languages—if not perfectly, in Jamie’s case. But apparently, their love is much stronger than his grasp on Portuguese grammar, because they’ve got three bilingual kids and another on the way. (And still enjoy having important romantic moments in the car.)

In 2015, Love Actually script editor Emma Freud revealed via Twitter what happened between Karen and Harry (Emma Thompson and Alan Rickman, who passed away last year). Most of the other couples get happy endings in the short—even if Hugh Grant's character hasn't gotten any better at dancing.

[h/t TV Guide]

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