Inspired by the design of a classic toy, two Stanford researchers have created a paper-based centrifuge that could revolutionize how infections like malaria and HIV are detected in the developing world.
“There are more than a billion people around the world who have no infrastructure, no roads, no electricity," said Manu Prakash, an assistant professor of bioengineering at Stanford. "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.”
Centrifuges are extremely vital in developing countries, where timely identification of infections like malaria, HIV, and tuberculosis is critical. Blood samples placed in the devices are spun at high speeds to separate the plasma, red blood cells, pathogens and parasites into distinct layers.
Unfortunately centrifuges are not only expensive, but require electricity to achieve their high rotation speeds. In far-flung corners of the world where access to both is prohibitive, devices that can achieve the same result and are affordable can make a huge impact.
In a paper published last week in Nature, Prakash explained how he and his team came up with a paper-based centrifuge after examining a whirligig; a centuries-old toy that spins faster the harder you pull on two strings. Using a high-speed camera, the researchers were able to determine that the simple device is capable of speeds of more than 10,000 to 15,000 rpm.
“There are some beautiful mathematics hidden inside this object,” Prakash said.
Using the initial concept as a baseline, the team was able to build an advanced whirligig capable of 125,000 rpm and exerting centrifugal forces of 30,000 Gs. After attaching a small sample to the wheel and pulling the strings, the blood achieved optimal separation after about 15 minutes.
These speeds, from a device that costs no more than twenty cents to create, is on par with centrifuges costing between $1,000-$5,000.
“To the best of my knowledge, it’s the fastest spinning object driven by human power,” Prakash added to the Stanford News.
The next step for the team is validate their prototype with a field trial focused on detecting Malaria.
"The simplicity of manufacturing our proposed device will enable immediate mass distribution of a solution urgently needed in the field," the team wrote. "Ultimately, our present work serves as an example of frugal science: leveraging the complex physics of a simple toy for global health applications."
You can see a video of the "paperfuge" in action below: