Jan 15, 2017 | By Benedict
Scientists at Stanford University have developed a potentially life-saving 3D printed tool inspired by a whirligig, a spinning toy that dates back to the Bronze Age. The new device could help healthcare workers diagnose malaria in areas lacking precise laboratory equipment.
Malaria, an infectious disease spread by mosquitoes, can cause fever, vomiting, fatigue, and—in extreme cases—death. The condition is easy to diagnose with proper medical equipment, but, understandably, that equipment is not always available. For medical workers working in remote places, however, there is a trick to diagnosing malaria: the use of a centrifuge. By spinning a blood sample very quickly, different cells types in the blood can be separated from each other, making it easier to spot parasites. The question then becomes: how does one acquire a centrifuge?
Manu Prakash, a professor of bioengineering at Stanford University, asked himself the same question during a trip to Uganda, when he encountered medical workers desperately needed a centrifuge—or, more specifically, one that could be powered without electricity. “We were out in a primary health center talking to health care workers and we found a centrifuge used as a doorstop because there’s no electricity,” Prakash said.
“There are more than a billion people around the world who have no infrastructure, no roads, no electricity,” Prakash continued. “I realized that if we wanted to solve a critical problem like malaria diagnosis, we needed to design a human-powered centrifuge that costs less than a cup of coffee,” said Prakash, who was senior author on the study.”
On his return to California, Prakash immediately began work on developing a centrifuge that would work even in areas without electricity. His inspiration? Children’s toys! At first, Prakash and a Stanford research team tried to harness the centrifugal power of a yo-yo, and were able to record pretty fast speeds. That, however, wasn’t quite enough—a faster spin was needed.
Reluctantly putting aside the yo-yo, Prakash and his team stumbled upon another popular spinning toy of yesteryear: the whirligig, or buzzer, an ancient toy (or ornament) consisting of a wheel in the center of a wire that spins by hand or wind power. “One night I was playing with a button and string, and out of curiosity, I set up a high-speed camera to see how fast a button whirligig would spin—I couldn’t believe my eyes,” said Saad Bhamla, a postdoctoral research fellow, upon discovering that the device was rotating at 10,000 to 15,000 revolutions per minute.
Capable of much faster spinning than the yo-yo, the team then went on to design an incredibly efficient whirligig, recording unprecedented speeds of 125,000 revolutions per minute. Since the first version of the rapid-fire whirligig was made from paper, the engineers called their device a “paperfuge.” (A 3D printed version would be made later on.)
To make a paperfuge, all that is required is paper coated with polymer film, string, and PVC pipe or wood. To operate it, blood samples are attached to the center disc, after which the user can pull on the string to commence the rapid revolutions. This speedy spinning causes the cells to separate, just as they would in a more expensive electrical centrifuge.
Before the researchers could draw a line under their project, they first had to ensure that the paperfuge would work out in the field. They consequently booked a trip to Madagascar to try out the device out for real. Thankfully, testing was a success, and local health care workers were able to spin blood samples in order to test for parasites. Better still, the paperfuge costs just 20 cents to make, and could therefore be used by any medical staff with access to the available materials.
In addition to creating paper versions of their device, the researchers also tried making a similar instrument with an SLA 3D printer. With this method, they were able to 3D print over 100 plastic whirligig devices in a day. They explain: “Using a desktop 3D printer (Form 2, Formlabs), we rapidly printed lightweight (20 g) prototypes of different ‘3D-fuges’ that spun at speeds of approximately 10,000 r.p.m. These further open opportunities to mass-manufacture millions of centrifuges using injection-moulding techniques.”
Though not as fast as the paper version of the paperfuge, the 3D printed devices could potentially be more durable and resilient—a useful attribute in places where access to the source materials is limited.
A research paper covering the development and testing of the paperfuge has been published in Nature Biomedical Engineering.
Posted in 3D Printing Application
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