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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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Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation
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Medicine
Bill Gates is Spending $100 Million to Find a Cure for Alzheimer's
Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation
Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation

Not everyone who's blessed with a long life will remember it. Individuals who live into their mid-80s have a nearly 50 percent chance of developing Alzheimer's, and scientists still haven't discovered any groundbreaking treatments for the neurodegenerative disease [PDF]. To pave the way for a cure, Microsoft co-founder and philanthropist Bill Gates has announced that he's donating $100 million to dementia research, according to Newsweek.

On his blog, Gates explained that Alzheimer's disease places a financial burden on both families and healthcare systems alike. "This is something that governments all over the world need to be thinking about," he wrote, "including in low- and middle-income countries where life expectancies are catching up to the global average and the number of people with dementia is on the rise."

Gates's interest in Alzheimer's is both pragmatic and personal. "This is something I know a lot about, because men in my family have suffered from Alzheimer’s," he said. "I know how awful it is to watch people you love struggle as the disease robs them of their mental capacity, and there is nothing you can do about it. It feels a lot like you're experiencing a gradual death of the person that you knew."

Experts still haven't figured out quite what causes Alzheimer's, how it progresses, and why certain people are more prone to it than others. Gates believes that important breakthroughs will occur if scientists can understand the condition's etiology (or cause), create better drugs, develop techniques for early detection and diagnosis, and make it easier for patients to enroll in clinical trials, he said.

Gates plans to donate $50 million to the Dementia Discovery Fund, a venture capital fund that supports Alzheimer's research and treatment developments. The rest will go to research startups, Reuters reports.

[h/t Newsweek]

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science
Eye Doctors Still Use This 100-Year-Old Test for Color Blindness

You may have seen them at your ophthalmologist's office: large circular diagrams made up of colored dots. People with normal vision are able to discern a number among the dots of contrasting colors. People who are color blind might see only a field of spots.

These elegant, deceptively modern drawings were published 100 years ago by a Japanese ophthalmologist, Shinobu Ishihara. Thanks to the designs' simplicity and diagnostic accuracy, the Ishihara test is still the most popular and efficient way to identify patients with color vision deficiencies.

Born in Tokyo in 1879, Ishihara studied medicine at the prestigious Tokyo Imperial University on a military scholarship, which required him to serve in the armed forces. After graduating in 1905, he worked for three years as a physician specializing in surgery in the Imperial Japanese Army, and then returned to the university for postgraduate studies in ophthalmology. In his research, Ishihara focused on identifying and recruiting soldiers with superior vision, thereby increasing the overall effectiveness of the military. And that became of prime importance to Japan beginning in 1914.

As World War I spread across Europe, Asia, and the Pacific, the Japanese army asked Ishihara to develop a better way to screen draftees for color vision problems. The most popular method at the time was the Stilling test, invented by German ophthalmologist Jakob Stilling in 1878 as the first clinical color vision test. (Previous tools had asked patients to identify the colors of wool skeins or illuminated lanterns—useful skills for sailors and railway conductors, but an imprecise method for diagnosing vision issues.)

"Though popular, 'the Stilling' retained a distinctly 19th-century flavor, more treatise-like and less diagnostically incisive," according to Eye magazine.


Shinobu Ishihara
Wellcome Images // CC BY 4.0

Japanese army officials requested a new diagnostic tool that was easier to administer and interpret. The test Ishihara began to develop was based, like Stilling's, on the principle of pseudo-isochromatism—a phenomenon in which two or more colors are seen as the same (or isochromatic) when they're actually different. A person with normal vision could easily see the difference, while people with red-green deficiency, the most common form of color blindness, would have difficulty distinguishing those two opposing colors. Those with blue-yellow color blindness, a less common type, would have a hard time discerning reds, greens, blues, or yellows.

Ishihara hand-painted circular designs comprised of small dots of different areas and colors so that variations in the design could be discerned only by color and not shape, size, or pattern. Hidden in the field of dots was a figure of a contrasting color that people with normal vision could see, while those with deficiencies could not. Other plates in the series were designed to show figures that would be visible only to people with deficiencies. When physicians displayed the diagrams, patients said or traced the visible figure within the circle without needing to use ambiguous color names, which standardized the possible results.

The earliest sets of Ishihara plates, produced in 1916, were reserved exclusively for the army's use and featured Japanese characters within the diagrams. In 1917, in an effort to sell the series internationally, Ishihara redesigned it with the now-familiar Arabic numerals and published a set of 16 plates as Tests for Colour Deficiency.

The tests were adopted throughout the world beginning in the early 1920s, and eventually grew into a set of 38 plates. But their popularity almost led to their undoing. Unauthorized publishers printed their own version of the plates to meet demand, throwing the accuracy of the diagnostic colors into doubt. "The plates have been duplicated along with an easily memorized key by cheap color processes in the tabloid press, and exposed in public places, reducing the fifth edition [of the collection] to a parlor game," one psychologist warned in the Journal of the Optical Society of America in 1943.

Despite those obstacles, the tests proved indispensable for both practicing physicians and researchers. Ishihara continued to refine the designs and improve the color accuracy of the images into the late 1950s, while he also served as the chair of the ophthalmology department and then dean of the medical school at Tokyo Imperial University. In addition to Tests for Colour Deficiency, he also published an atlas, textbook, lectures, and research studies on eye diseases. But he is remembered most for the iconic charts that seamlessly blend art and science.

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