Lights and Brains: Injectible LED's Interact with Brain Cells

The quest to put computers in the brain has just come a step closer.  Tiny LED lights have been implanted deep in the brains of rodents.  The LEDs themselves are the size of individual neurons.  They are packaged with other tiny sensors into an ultrathin, flexible device.  The whole device is small enough to be implanted using a needle that positions the device at precise sites deep in the brain. 

Once implanted, the device communicates directly with the brain at the level of cells.  It communicates wirelessly with a module mounted above the rodent’s head, one small enough not to interfere with activity and removable when not in use.  The device itself is completely contained within the brain where it was implanted without any damage to surrounding cells.  Signals sent through the device stimulate genetically modified brain cells, signaling for example for the release of neurotransmitters such as dopamine. 

Photo Credit: MicroLED device next to a human finger.  Image courtesy of University of Illinois-Urbana Champaign and Washington University-St. Louis.

 

"These materials and device structures open up new ways to integrate semiconductor components directly into the brain," said team co-leader John A. Rogers according to a press release from the University of Illinois.  "More generally, the ideas establish a paradigm for delivering sophisticated forms of electronics into the body: ultra-miniaturized devices that are injected into and provide direct interaction with the depths of the tissue."

The device itself is a feat of engineering requiring the effort of an international team based in China, Korea, and at multiple centers across the US.  By miniaturizing the device to the cellular scale and by creating a totally wireless interface, researchers overcame several challenges at once.  For example, larger implantable devices always run the risk of creating scars or lesions in the brain, which may cause serious problems.   "One of the big issues with implanting something into the brain is the potential damage it can cause," team co-leader Michael Bruchas said. "These devices are specifically designed to minimize those problems, and they are much more effective than traditional approaches."

In addition, because this device communicates and receives its power wirelessly, there are no wires or optical fibers passing from the brain to the outside world.  Previous devices were larger and nonflexible. They were implanted only on the surface of brain structures, but this new device is implantable deep within those structures and able to interact with units as small as a single cell.

Along with the LED lights, the device includes temperature and light sensors, microscale heaters, and electrodes that can stimulate and receive brain electrical activity.  Power to the device is provided wirelessly through a radio frequency system. 

It is impossible to predict the future of efforts to connect brains and computers. This work obviously represents a significant advance toward that end.  "These cellular-scale, injectable devices represent frontier technologies with potentially broad implications," Rogers said. Being able to monitor and trigger the brain of living animals at the cellular level is likely to become a profoundly valuable tool for research.  Medical research, too, is also likely to be affected, not just in responding to patients with paralysis but also in research and perhaps even therapy in other diseases involving the brain or other organs, where these devices are also implantable. 

Some, of course, will speculate about even wider implications for this technology.  Will it open the way to control people by controling their brains?  Perhaps.  Will it open the way for our brains to communicate with computers and the internet?  There is little doubt that this step will inspire more work along those lines. 

This article is entitled "Injectable, Cellular-Scale Optoelectronics with Applications for Wireless Optogenetics" and is published in the April 12, 2012 issue of the journal Science, a publication of the American Association for the Advancement of Science.