Cellphone that Can Be Implanted into the Brain

Neuroengineers from Brown University in USA have developed a fully implantable and rechargeable wireless brain sensor capable of relaying real-time broadband signals from up to 100 neurons in freely moving subjects.

Several copies of the novel low-power device, described in the Journal of Neural Engineering, have been performing well in animal models for more than year, a first in the brain-computer interface field.

Brain-computer interfaces could help people with severe paralysis control devices with their thoughts.

Arto Nurmikko, professor of engineering at Brown University said that the device "has features that are somewhat akin to a cell phone, except the conversation that is being sent out is the brain talking wirelessly,"

Neuroscientists can use such a device to observe, record, and analyze the signals emitted by scores of neurons in particular parts of the animal model's brain.

Meanwhile, wired systems using similar implantable sensing electrodes are being investigated in brain-computer interface research to assess the feasibility of people with severe paralysis moving assistive devices like robotic arms or computer cursors by thinking about moving their arms and hands.

This wireless system addresses a major need for the next step in providing a practical brain-computer interface," said neuroscientist John Donoghue, the Wriston Professor of Neuroscience at Brown University and director of the Brown Institute for Brain Science.

In the device, a pill-sized chip of electrodes implanted on the cortex sends signals through uniquely designed electrical connections into the device's laser-welded, hermetically sealed titanium "can."

The can measures 2.2 inches (56 mm) long, 1.65 inches (42 mm) wide, and 0.35 inches (9 mm) thick.

That small volume houses an entire signal processing system: a lithium ion battery, ultralow-power integrated circuits designed at Brown for signal processing and conversion, wireless radio and infrared transmitters, and a copper coil for recharging - a "brain radio." All the wireless and charging signals pass through an electromagnetically transparent sapphire window.

In all, the device looks like a miniature sardine can with a porthole.

The device transmits data at 24 Mbps via 3.2 and 3.8 Ghz microwave frequencies to an external receiver. After a two-hour charge, delivered wirelessly through the scalp via induction, it can operate for more than six hours.