Cornell University researchers and collaborators have developed an entirely tiny neural implant. Despite its size, the device can wirelessly transmit brain activity data from live animals for more than a year.
Progress reported in nature electronicsshows that microelectronic systems can operate on very small scales. This could open the door to new approaches in brain monitoring, biointegrated sensors, and other medical and technological applications.
What is a MOTE device
This device is known as a microscale optoelectronic tetherless electrode (MOTE). Its development was led by Alyosha Molnar, a professor in the Department of Electrical and Computer Engineering at Cornell University, and Seung-woo Lee, an assistant professor at Nanyang Technological University. Lee started working on this technology early on as a postdoctoral fellow in Molnar’s lab.
How implants use light to send brain signals
MOTE works using red and infrared laser beams that safely pass through brain tissue. It sends data back by emitting small pulses of infrared light that encode electrical signals from the brain.
At the core of the device is a semiconductor diode made from aluminum gallium arsenide. This component captures incoming light to power the system and emits light to transmit data. The implant also includes a low-noise amplifier and optical encoder, both built with the same type of semiconductor technology used in everyday microchips.
The device measures approximately 300 microns long and 70 microns wide.
“As far as we know, this is the smallest neural implant that measures electrical activity in the brain and reports it wirelessly,” Molnar said. “By using pulse position modulation in the code, for example, the same code used in optical communications in satellites, we can successfully retrieve the data optically while using very little power for communication.”
Future applications of brain and body monitoring
Molnar said the materials used in MOTE could allow researchers to record brain activity during MRI scans, something that is nearly impossible with current implants. The technology could be applied to other parts of the body, including the spinal cord, and could eventually be combined with future innovations such as optoelectronics embedded in artificial skull plates.
