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Stanford University
Stanford University

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

Stanford University
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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Karen Bleier, AFP/Getty Images
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Medicine
Bill and Melinda Gates Will Repay Nigeria's $76 Million Polio-Fighting Loan
Karen Bleier, AFP/Getty Images
Karen Bleier, AFP/Getty Images

Not long after announcing a $100 million donation to find a cure for Alzheimer's disease, Bill and Melinda Gates have agreed to pay off Japan's $76 million loan to Nigeria to stamp out polio, Quartz reports.

Polio has been eradicated in most countries around the world, but it's still present in Nigeria, as well as in Afghanistan and Pakistan. In 2008, according to The Conversation, Nigeria accounted for 86 percent of all polio cases in Africa. This high number was thanks in part to low immunization rates and calls from extremists to boycott polio vaccinations out of fear that they were tainted with anti-fertility steroids.

National and international campaigns were launched to lower polio rates in Nigeria, and in 2014 the nation received the loan from Japan to boost disease-fighting efforts. Progress has been made since then, with no new cases of polio reported in Nigeria in 2017. Two children had contracted polio in 2016, two years after Nigeria's last known case.

Nigeria's loan repayments to Japan were slated to begin in 2018. The Bill & Melinda Gates Foundation agreed to cover the costs after Nigeria met its goal of "achieving more than 80 percent vaccination coverage in at least one round each year in very high risk areas across 80 percent of the country's local government areas," Quartz reports. The loan will be repaid over the next 20 years.

While the Gates Foundation is lending a hand to Nigeria, the Associated Press reports that health officials in Pakistan's eastern Punjab province recently launched a new chapter in the nation's ongoing struggle against the disease. Health workers will engage in a week-long, door-to-door vaccination campaign, though efforts like this are risky due to threats from the Taliban and other militant groups, who view vaccinations as a Western conspiracy and believe they sterilize children. Anti-polio efforts in Pakistan also suffered after the CIA used vaccinations as a cover to get DNA samples from the Bin Laden compound.

[h/t Quartz]

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George Mayerle, U.S. National Library of Medicine // Public Domain
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Design
This 1907 Vision Test Was Designed for People of All Nationalities
George Mayerle, U.S. National Library of Medicine // Public Domain
George Mayerle, U.S. National Library of Medicine // Public Domain

At the turn of the 20th century, San Francisco was a diverse place. In fact, Angel Island Immigration Station, located on an island in the San Francisco Bay, was known as the “Ellis Island of the West,” processing some 300,000 people coming to the U.S. in the early 1900s. George Mayerle, a German optometrist working in the city at the time, encountered this diversity of languages and cultures every day in his practice. So in the 1890s, Mayerle created what was billed as “the only [eye] chart published that can be used by people of any nationality,” as The Public Domain Review alerts us.

Anticipating the difficulty immigrants, like those from China or Russia, would face when trying to read a vision test made solely with Roman letters for English-speaking readers, he designed a test that included multiple scripts. For his patients that were illiterate, he included symbols. It features two different styles of Roman scripts for English-speaking and European readers, and characters in Cyrillic, Hebrew, Japanese, and Chinese scripts as well as drawings of dogs, cats, and eyes designed to test the vision of children and others who couldn't read.

The chart, published in 1907 and measuring 22 inches by 28 inches, was double-sided, featuring black text on a white background on one side and white text on a black background on the other. According to Stephen P. Rice, an American studies professor at Ramapo College of New Jersey, there are other facets of the chart designed to test for a wide range of vision issues, including astigmatism and color vision.

As he explains in the 2012 history of the National Library of Medicine’s collections, Hidden Treasure [PDF], the worldly angle was partly a marketing strategy on Mayerle’s part. (He told fellow optometrists that the design “makes a good impression and convinces the patient of your professional expertness.”)

But that doesn’t make it a less valuable historical object. As Rice writes, “the ‘international’ chart is an artifact of an immigrant nation—produced by a German optician in a polyglot city where West met East (and which was then undergoing massive rebuilding after the 1906 earthquake)—and of a globalizing economy.”

These days, you probably won’t find a doctor who still uses Mayerle’s chart. But some century-old vision tests are still in use today. Shinobu Ishihara’s design for a visual test for colorblindness—those familiar circles filled with colored dots that form numbers in the center—were first sold internationally in 1917, and they remain the most popular way to identify deficiencies in color vision.

[h/t The Public Domain Review]

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