Cornell researchers developed MOTE, a microscale, untethered optoelectronic electrode about 300 μm × 70 μm that records neural electrical activity and transmits data as infrared pulses. Tested first in cell cultures and then implanted in the mouse barrel cortex, MOTEs reliably recorded action potentials and synaptic activity for over a year. The device is MRI‑compatible and designed to reduce tissue irritation; the team notes it could be adapted for other sensitive tissues, though human translation requires further testing and regulatory review.
Rice‑Grain Wireless Brain Implant Records Neural Activity for Over a Year
Cornell researchers developed MOTE, a microscale, untethered optoelectronic electrode about 300 μm × 70 μm that records neural electrical activity and transmits data as infrared pulses. Tested first in cell cultures and then implanted in the mouse barrel cortex, MOTEs reliably recorded action potentials and synaptic activity for over a year. The device is MRI‑compatible and designed to reduce tissue irritation; the team notes it could be adapted for other sensitive tissues, though human translation requires further testing and regulatory review.
04:33, 08.11.2025Technology
Rice‑grain MOTE: a tiny, wireless brain implant
Researchers at Cornell University report a major step forward in microscale neural interfaces with a device small enough to sit on a grain of rice. The microscale optoelectronic tetherless electrode ("MOTE") is an untethered, optically powered implant that records electrical activity in the brain and transmits data wirelessly using infrared light.
How MOTE works
MOTE measures roughly 300 microns long by 70 microns wide — about the width of a single human hair. At its core is a semiconductor diode made from aluminum gallium arsenide that both harvests light for power and emits optical signals to send data. A low‑noise amplifier and an optical encoder process neural signals, and data are transmitted using pulse‑position modulation, a low‑power optical encoding method also used in satellite optical communications.
Lab and animal testing
The team first validated the approach in lab‑grown cell cultures and then implanted MOTEs into mice. Devices were placed in the barrel cortex, the region specialized for processing whisker input, and recorded reliably for more than a year. During that time MOTE detected action potential spikes and broader synaptic activity in both active and otherwise healthy animals, demonstrating durable chronic recordings.
Alyosha Molnar, an electrical engineer and co‑author, said: "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."
Advantages and potential applications
MOTE's untethered, optoelectronic design reduces mechanical irritation and the immune response that can be triggered by larger electrodes or fixed optical fibers. Because it uses materials compatible with electrical monitoring equipment, the device may avoid the MRI constraints faced by many current implants. The authors suggest the same design principles could be adapted for other sensitive tissues, such as the spinal cord, or embedded in artificial skull plates for long‑term physiological sensing.
Limitations and next steps
While results in cell cultures and mice are promising, translation to human use will require extensive additional testing, miniaturized packaging for safe implantation, long‑term biocompatibility studies, and regulatory approval. The study demonstrates an important proof of concept for low‑power, chronic optical neural interfaces but stops short of clinical readiness.
Conclusion: MOTE represents a notable advance in minimizing implant size while maintaining chronic neural recording capability. Its optical power and data link, MRI‑friendly materials, and small form factor make it a compelling platform for further development across neuroscience and medical applications.