Neural implants that read the electrical activity of the brain are no longer the work of fiction, improving over the years in their ability to gather ever larger amount of signals and being able to more effectively process them. Some serious practical limitations have continued to exist, primarily because the implants had to be wired to external computers for data transmission and to receive current that powers them. Now a team from Brown University, working with help from the folks at BrainGate, has developed a fully implantable sensor that both shares its readings and recharges wirelessly. In the latest Journal of Neural Engineering, the researchers have reported that the new device has been successfully working in three pigs and three macaque monkeys for over a year.
The implant works off of less than 100 milliwatts of electricity and can be recharged in two hours for a six hour run time. It was tested using single 100 electrode arrays, but has the capability of working with larger signal sources. It’s being presented this week at the 2013 International Workshop on Clinical Brain-Machine Interface Systems in Houston.
From the announcement:
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.
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 team worked closely with neurosurgeons to implant the device in three pigs and three rhesus macaque monkeys. The research in these six animals has been helping scientists better observe complex neural signals for as long as 16 months so far. In the new paper, the team shows some of the rich neural signals they have been able to record in the lab. Ultimately this could translate to significant advances that can also inform human neuroscience.
Study abstract in Journal of Neural Engineering: An implantable wireless neural interface for recording cortical circuit dynamics in moving primates
Press release: Brown unveils novel wireless brain sensor