Brain-computer interfaces (BCIs) appeared as assistive devices, that may one day help people with brain or spine injuries to perform functions. BCI systems depend on embedded sensors that record electrical signals in the brain. These signals are used to drive external devices like computers or robotic liposuction.
Today brain transplants are immense and can only record from one or two locations. Tiny neurogranin is used to record and revive neurons wirelessly in multiple locations in rat brains. Researchers have been working on BCIs that can record and stimulate group neurons for more than ten years. But in recent years, there has been an interest in using them to treat injuries and diseases like Epilepsy, Parkinson’s, or various psychiatric disorders.
They could soon be implanted in healthy people to help us monitor our brain function and even improve it. Elon Musk said brain implants being built by his startup Neuralink are like a Fitbit in your skull. They will have to get much more accurate and far less out of place.
A research team at Brown University made a significant move on that problem by developing tiny implants measuring less than 0.1 cubic millimeters. The implants can record as well as stimulate brain activity. These neurograins are combined to create a network of implants that can be controlled wirelessly.
Arto Nurmikko, who led the research team, said that one of the complex challenges in brain-computer interfaces is engineering ways of probing as many points in the brain as possible. Until now, most BCIs have been vast devices and a bit like little beds of needles. Each chip features electrodes to pick up electrical signals from the brain tissue, circuitry to amplify the signal, and a tiny coil of wire that sends and receives wireless signals. The chips are attached to the surface of the brain. A thin relay coil helps improve wireless power transfer to the neurograins laid over the area where they allocate.
A thin layer containing another coil is attached to the outside of the scalp above the relay coil. Like a mini cellphone tower using a specially-designed network protocol to connect to each neurograins individually. It also transmits power to the neurograins. The concept of neural dust was developed at the University of California, Berkley. In the paper of Nature Electronics, the team showed that they could implant 48 of the tiny chips into the rat brain. Then use it to record and stimulate neural networking.
The researchers say the recordings have room for upgrade, but they pick up impulsive brain signals and detect using an ordinary implant. They showed that they could direct a single neurogranin to stimulate neural activity then take hold of conventional recording devices.
The current setup could support up to 770 neurograins, but they envision scaling to thousands. The paper notes that the chip design should translate from the 65-nanometer fiction process and, it currently uses a 22 nanometer one. The same group has also developed a novel method for implanting large numbers of tiny wireless sensors into soft tissue.
To improve the quality of the recordings, work needed on the implants is necessary to verify their safety in humans. But the ability to coordinate many small implants into a network is the main focus, with plenty of capacity for research and medicine.
Writer: Amina Kiani
Reported by: Imaaz Nadeem