A lens-free microscope that borrows tech from your cellphone
Scientists at UCLA have created a lens-free microscope that relies on a silicon chip found in smartphones and digital cameras. You can’t use it to snap a selfie, but it could help scientists detect cancer.
In a paper published Wednesday in Science Translational Medicine, the research team shows that images taken with the lens-free microscope were just as capable of revealing cellular abnormalities in tissue samples as more traditional, and more expensive light microscopes.
“Our microscope provides the same level of quality as a state-of-the-art optical light microscope, and it has a significantly larger field of view, a simpler design, and it is more cost-effective,” said Aydogan Ozcan, a professor of electrical engineering at UCLA and the senior author on the paper.
Ozcan’s lab specializes in creating computer codes that simplify the design of microscopes, nanoscopes and other instruments, and improve their performance.
His team recently created a device that turns a smartphone into a high-powered microscope capable of imaging individual DNA molecules. Another project turned Google Glass into a tool that can perform diagnostic tests on blood and tissue samples.
Like much of Ozcan’s work, the design of the lens-free microscope borrows from existing technology.
“The bread and butter of this project is a CCD or CMOS imager, which is the same thin chip you find in every digital camera, whether it’s a high-end SLR or a cellphone camera,” he said.
The setup also requires a light source and a sample holder that keeps the slide hovering just a little above the chip. When the light shines down on the sample slide, the slide casts a shadow of the sample tissue onto the imaging chip.
You can get an idea of how this works by holding your hand above your desk and under a light source. The closer to the desk you put your hand, the more defined the shadow becomes. The shadow of your hand is solid, but because cells are translucent, their shadows are more detailed.
The shadow image the chip collects is a murky-looking holograph that bears little resemblance to what you would see if you looked at the same slide through a light microscope. After the image is captured, it is reconstructed with software developed by Ozcan’s team that converts the messy patterns into an image that is at least as clear as what you would see through a traditional microscope.
“The hardest part was creating the computational transformation that takes those nasty-looking shadowy patterns and give you the truth of what is happening,” Ozcan said. “That was the computational puzzle.”
Ozcan and his team tested the accuracy of their microscope by showing a board-certified pathologist 150 images of breast cancer tissue — some taken with a light microscope, others taken with the lens-free microscope. The pathologist was asked to analyze the images and note if the samples showed benign cells, atypical cells or invasive carcinoma.
The pathologist had 99% accuracy using images acquired by the lens-free microscope, and 100% accuracy with images from the light microscope.
Still, the lens-free microscope is not ready for prime time Ozcan said. Most importantly, the computer software that lets a user look at the digitally constructed image on a computer screen needs to be more user friendly.
“You can think of our interface as a very early version of the personal computer, where you have to write code to do anything,” said Ozcan. “For other people to use it, it needs to be like Windows.”
Eventually, however, the team would like to see the microscope used in parts of the world where access to medical infrastructure is limited.
“A small nurse’s office that doesn’t have a pathologist on staff could transmit digital images created by our microscope to an expert in another city, or another country,” he said. “Mobile health and global health is where I would like to channel the things we create.”
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