Bioengineer designs diagnostic microscope costing less than $1

- By Kris Newby

It’s an invention that would make TV’s secret agent MacGyver proud: a fully functional microscope that can be assembled from folded paper and a tiny bead of glass. And it only costs about 50 cents.

By adding a watch battery, a light-emitting diode and an on/off switch, it can be configured to diagnose blood-borne diseases such as malaria, African sleeping sickness, schistosomiasis and Chagas — all for under a dollar.

The Foldscope is the brainchild of Manu Prakash, PhD, assistant professor of bioengineering. He developed the idea during medical need-finding trips to India, Thailand, Uganda and Nigeria with graduate students James Cybulski and James Clements. During the trip, the team witnessed the deadly toll of infectious diseases including malaria, and noted that many of the remote villages couldn’t afford conventional microscopes or rapid diagnostics tests.

“I realized that to make a real impact, we needed to deliver a disease-detection instrument that could almost be distributed for free,” Prakash said.

After three years of research, prototyping and extensive field-testing in Southeast Asia and Africa, the Foldscope was born. Design and construction details of this bookmark-sized microscope were released March 5 in arXiv, a scientific paper archive. You can watch the Foldscope in action in the video and on the TED website.

Foldscope design

The Foldscope includes no mechanical moving parts, packs in a flat configuration, is extremely rugged and can be incinerated after use to safely dispose of infectious biological samples. With minor design modifications, it can be used for bright-field, multi-fluorescence or projection microscopy.

One of the unique design features of the microscope is the use of inexpensive microlenses instead of the precision-ground, curved, glass lenses used in traditional microscopes. These poppy-seed-sized lenses were originally mass-produced in various sizes as an abrasive grit that was thrown into industrial tumblers to knock the rough edges off metal parts. In the simplest configuration of the Foldscope, one 17-cent lens is press-fit into a small hole, call an aperture, in the center of the slide-mounting platform. Some of the more sophisticated versions have multiple lenses, including condenser lenses, doublet lenses and light filters.

James Duncan Davidson / TED Manu Prakash with paper microscope

Manu Prakash thought up the origami-style paper microscope and led the team that developed it.

To use a Foldscope, a sample is mounted on a microscope slide and inserted in a slot in the microscope. With a thumb and forefinger grasping each end of the layered paper strip, a user holds the microscope close to one eye. Focusing and locating a target object are achieved by flexing and sliding the paper platform with the thumb and fingers.

Because of the unique optical physics of a spherical lens held close to the eye, in certain configurations samples can be magnified up to 2,000 times.

The Foldscope can be customized for the detection of specific organisms by adding various combinations of components, sample stains and light filters. An important feature of the microscopes is that they can be configured to act like projectors, enabling large microscopic images to be displayed on wall or table surfaces. This allows health workers or teachers to share microscopic images with a large number of viewers in field settings, making it an effective teaching tool.

Based on field testing in Uganda, the team estimates that a typical Foldscope can be used for months before it needs to be discarded. Further cost savings could be realized by mass-producing the microscopes on roll-on-roll printers and print-and-fold manufacturing machines. In this coming year, his team will do international fieldwork in both diagnostics and education to provide input for further refinement of their microscope designs.

Educational uses

Prakash has big plans for using Foldscopes in education, from training health workers to teaching science, technology and engineering.

“Many children around the world have never used a microscope, even in developed countries like the United States,” Prakash said. “A universal program providing a microscope for every child could foster deep interest in science at an early age.”

In a recent Stanford bioengineering course, Prakash used the Foldscope to teach students about the physics of microscopy. He had each student shape their own Foldscope from a die-cut paper pattern. Then teams designed Foldscope accessories, such as a smartphone camera attachment, or wrote reports on microscopic observations.

His next educational effort, funded by the Gordon and Betty Moore Foundation, is the “Ten Thousand Microscopes Project.” For this initiative, 10,000 build-your-own-Foldscope kits will be given away to the citizen-scientists with the best ideas for science experiments, protocols, queries and applications that use a Foldscope.

“We aim to collectively write a crowd-sourced biology microscopy manual with the examples collected from the scientists, teachers, tinkerers, thinkers, hackers and kids who participate,” Prakash said. “So many times people use a tool for one specific purpose and don’t realize the rich potential for other uses. This online manual will inspire further explorations.”

To apply for a free Foldscope kit, submit a one-page proposal to Recipients must commit to documenting their experiments such that they can be replicated by anyone. Submission details and sample ideas are posted at Kits will be shipped in August to the applicants with the best ideas.

“My dream is that someday, every kid will have a Foldscope in their back pocket,” Prakash said.

The research has been supported by the Frederick E. Terman Fellowship; the Donald E. and Delia B. Baxter Foundation; the Wallace H. Coulter Foundation; Spectrum, the Stanford Center for Clinical and Translational Research and Education; C-IDEA, Stanford's Consortium for Innovation, Design, Evaluation and Action; the Bill and Melinda Gates Foundation; Pew Scholars Program in the Biomedical Sciences; the Gordon and Betty Moore Foundation; the NIH Fogarty Institute Global Health Equity Scholars Fellowship; and the National Science Foundation Graduate Research Fellowship Program.

About Stanford Medicine

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