"This has features that are somewhat akin to a cell phone, except the conversation that is being sent out is the brain talking wirelessly," Arto Nurmikko, professor of engineering at Brown University said in a statement. Neuroscientists can use such a device to observe, record, and analyse the signals emitted by scores of neurons in particular parts of the animal model's brain.
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 long, 1.65 inches wide, and 0.35 inches 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. However, what the team has packed inside makes it a major advance among brain-machine interfaces, said lead author David Borton, a former Brown graduate student.
"Most importantly, we show the first fully implanted neural interface microsystem operated wirelessly for more than 12 months in large animal models - a milestone for potential (human) clinical translation," said Borton. 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. "The device uses less than 100 milliwatts of power, a key figure of merit," Nurmikko said.