Device Smaller Than Grain Of Salt Can Now Wirelessly Track Brain Signals

In a groundbreaking development, researchers at Cornell University have engineered a microscopic brain implant smaller than a grain of salt that can wirelessly transmit neural activity in a living animal for more than a year. Detailed in Nature Electronics, the device, called a microscale optoelectronic tetherless electrode, or MOTE, opens new possibilities for microelectronic systems that can function at an unprecedentedly small scale for neural monitoring and bio-integrated sensing, among other applications.

Despite being only 300 microns long and 70 microns wide, the MOTE is packed with cutting-edge tech. It is powered by red and infrared laser beams that pass harmlessly through brain tissue, allowing it to send data back using pulses of infrared light that encode the brain's electrical signals.

“As far as we know, this is the smallest neural implant that will measure electrical activity in the brain and then report it out wirelessly,” said Alyosha Molnar, a professor in the school of electrical and computer engineering who co-led the project.

“By using pulse position modulation for the code, the same code used in optical communications for satellites. For example, we can use very, very little power to communicate and still successfully get the data back out optically.”

To test the device, the researchers initially used cell cultures before implanting it into mice's barrel cortex, which is part of the brain that processes sensory information via whiskers. Over the course of a year, MOTE successfully recorded neuron activity while the mice remained healthy and active.

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New Avenues

Molnar explained that MOTE's material composition could make it possible to collect electrical recordings from the brain during MRI scans, which is not feasible with current implants.

Additionally, the technology could be adapted for use in other tissues, such as the spinal cord and even paired with future innovations like opto-electronics embedded in artificial skull plates.