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JUL/AUG 2013  

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Tiny, injectable LEDs to help neuroscientists study the brain

Researchers at the University of Illinois at Urbana-Champaign and Washington University in St. Louis developed ultrathin, flexible optoelectronic devices—including LEDs the size of individual neurons—that will aid neuroscientists in studying the brain, according to the University of Illinois.

The researchers demonstrated the first application of their devices in optogenetics, a new area of neuroscience that uses light to stimulate targeted neural pathways in the brain, according to the university. The procedure involves genetically programming specific neurons to respond to light. Optogenetics allows researchers to study precise brain functions in isolation in ways that are not possible with electrical stimulation, which affects neurons throughout a broad area, or with drugs, which saturate the whole brain.

While many important neural pathways can be studied by optogenetics, researchers continue to struggle with the engineering challenge of delivering light to precise regions deep within the brain. The most widely used methods tether animals to lasers with fiber-optic cables embedded in the skull and brain, which is an invasive procedure that also limits movements.

UofI RogersThe newly developed technologies bypass these limitations with specially designed powerful LEDs—among the world’s smallest, with sizes comparable to single cells—that are injected into the brain to provide direct illumination and precise control, according to the university. 

A thin plastic ribbon printed with advanced electronics is threaded through the eye of an ordinary sewing needle. The device, containing LEDs, electrodes and sensors, can be injected into the brain or other organs. Photo credit: John A. Rogers

The devices are printed onto the tip end of a thin, flexible plastic ribbon that is thinner than a human hair and narrower than the eye of a needle and that can insert deep into the brain with very little stress to tissue.

The complete device platform includes LEDs, temperature and light sensors, microscale heaters and electrodes that can both stimulate and record electrical activity. These components enable many other important functions. For example, researchers can measure the electrical activity that results from light stimulation, giving additional insight into complex neural circuits and interactions within the brain.

The research is being led by John A. Rogers, the Swanlund professor of materials science and engineering at the U. of I., and Michael R. Bruchas, a professor of anesthesiology at Washington University, who will publish their work in the April 12 issue of the journal Science.

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