Fiber-Optic Electro-Wetted Lens Could Answer Brain-Teasing Questions on the Brain

A team of bioengineers at the University of Colorado have designed a fiber-optic electro-wetted microscope to image and navigate a living brain.

The liquid lens is capable of fast-focusing within the brain cavity. This fast-focusing is made possible by applying an electric charge across two liquids that changes the lens’ curvature. This fast-focusing makes the lens less sensitive to motion.

“We also used a fibre bundle, which is a bundle of 10,000 to 30,000 tiny optical fibres, that allows us to translate the image from a desktop microscope to the adaptor that sits on the mouse’s head,” said Baris Ozbay, PhD candidate in bioengineering.

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“Microscopes today penetrate only about one millimeter into the brain but almost everything we want to see is deeper than that,” said Diego Restrepo, director of the Center for NeuroScience at the University of Colorado Anschutz Medical Campus. “You can manipulate this lens while most others are fixed. That means you can see neurons firing inside a living brain.”

The microscope is about half an inch in diameter. It includes a fiber optic cord which allows the mouse to function normally as its cranium is monitored. By implanting the camera onto the mouse long-term, researchers will be able to produce volumetric images by changing the focus. As this microscope can peer deeper into the brain cavity, parts of the brain that were hard to image using traditional microscopes can be processed into 3D high-resolution images in real time.

“Using optical methods to stimulate and record from neurons is the future of neuroscience research,” said Ozbay. “But most researchers are adapting existing large microscopes to fit mice for head-fixed imaging, which limits movement, is difficult to set up and has issues with motion. The solution is to put the microscope on the mouse, rather than putting the mouse on the microscope.”

“We can now measure a large region and sample more neurons,” said Emily Gibson, assistant professor in bioengineering at the University of Colorado. “For example, we can image up to 100 neurons at the same time, as opposed to perhaps the 10 or so we could do in the past.”

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Restrepo explained future applications of the lens design. He said, “This would have applications for Parkinson’s disease. There is something called brain stimulation; what happens there is they have to put an electrode in a small area of the brain. This [lens] will allow you to look at the structures as you go into the brain.”

He added, “The ability to see beneath the surface of the brain offers new, powerful ways to study brain function. It will help us understand brain disease and formulate new treatments.”

Other applications of the microscope include:

Screening pharmaceuticals which target sections of the brain
Optical, in situ, biopsies
The examination of neural damages and the control of prosthetic limbs

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