World’s smallest neural implant tracks brain signals through light

Cornell researchers have developed the world’s smallest neural implant, called the microscale optoelectronic tetherless electrode (MOTE), which is about the size of a grain of salt (approximately 300 microns long and 70 microns wide). This implant is capable of wirelessly recording brain activity in living animals for over a year by using harmless red and infrared laser beams to power the device and transmit data through tiny pulses of infrared light. The implant’s semiconductor diode, made from aluminum gallium arsenide, captures light energy to power the circuit and sends encoded brain signals optically, employing pulse position modulation to minimize power consumption while maintaining effective data communication. The MOTE was tested in mice by implanting it in the barrel cortex, where it successfully recorded neuron spikes and synaptic activity continuously for a year without causing adverse effects or immune responses. Its extremely small size reduces brain tissue irritation and avoids the complications associated with traditional electrodes and optical fibers, which often provoke immune reactions due to tissue movement