Scientists have created a brain implant so small it can sit on a grain of salt—yet powerful enough to wirelessly record brain activity for over a year.
The device, developed by researchers at Cornell University and Nanyang Technological University, represents a major leap forward in neuroscience and bioengineering.
Their findings were published in Nature Electronics on November 3.
The new implant, called a microscale optoelectronic tetherless electrode, or MOTE, can monitor the brain without wires, batteries, or bulky equipment.
Measuring just 300 microns long and 70 microns wide—smaller than the thickness of a human hair—the MOTE could transform how scientists study the brain and develop treatments for neurological conditions.
The device is powered by beams of red and infrared light that can safely pass through brain tissue.
These laser beams energize the implant’s tiny circuit, which then sends information back using pulses of infrared light.
These light pulses carry the brain’s electrical signals, allowing researchers to “see” what neurons are doing in real time.
The implant’s components include a miniature light-sensitive diode made from aluminum gallium arsenide, along with a low-noise amplifier and optical encoder—the same type of technology used in modern microchips.
Professor Alyosha Molnar, who co-led the project at Cornell, explained that the MOTE uses an extremely efficient communication system called pulse position modulation.
“It’s the same coding technique used in satellite optical communications,” he said. “This allows us to use very little power while still getting the data out clearly.”
To test the device, the researchers implanted it into the barrel cortex of mice, the part of the brain that processes whisker movements. Over the course of a year, the implant successfully recorded both quick neuron spikes and broader patterns of brain activity. Importantly, the mice remained healthy and behaved normally throughout the study.
Traditional brain electrodes can irritate brain tissue and trigger immune responses, but the MOTE’s tiny size minimizes these risks. It can measure brain signals faster than imaging systems and doesn’t require genetic modification of neurons.
Molnar added that the implant’s materials may even allow it to work safely during MRI scans—something current implants can’t do.
Beyond the brain, the MOTE could one day be used in other parts of the nervous system, like the spinal cord, or integrated into future medical technologies such as artificial skull plates with built-in sensors.
This breakthrough marks an exciting step toward ultra-miniature medical implants that can monitor, heal, and connect with the body’s most complex organ—the brain.
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