Harvard scientists have developed an electrical scaffold that can be injected directly into the brain with a syringe. By using the technique to “cyborg”-ize the brains of mice, the team was able to investigate and manipulate the animals’ individual neurons—a technological feat the researchers say holds tremendous medical promise.
Above: Bright-field image showing the mesh electronics being injected through sub-100 micrometer inner diameter glass needle into aqueous solution. (Lieber Research Group/Harvard University
As reported in Nature News, the soft, conductive polymer mesh can be injected into a mouse’s brain, where it unfurls and takes root. And because the mesh can be laced with tiny electronic devices, the implant can be custom-designed to perform a number of tasks, from monitoring brain activity to stimulating brain functions. Once proven safe, the technology could be applied in humans, where it could be used to treat Parkinson’s, among other cognitive disorders. The details of this research, led by Harvard’s Charles Lieber, can be found in the journal Nature Nanotechnology.
“I do feel that this has the potential to be revolutionary,” Lieber noted in a Harvard statement. “This opens up a completely new frontier where we can explore the interface between electronic structures and biology. For the past 30 years, people have made incremental improvements in micro-fabrication techniques that have allowed us to make rigid probes smaller and smaller, but no one has addressed this issue — the electronics/cellular interface — at the level at which biology works.”
Nature News’s Elizabeth Gibney explains how it works:
The Harvard team [used] a mesh of conductive polymer threads with either nanoscale electrodes or transistors attached at their intersections. Each strand is as soft as silk and as flexible as brain tissue itself. Free space makes up 95% of the mesh, allowing cells to arrange themselves around it.
In 2012, the team showed that living cells grown in a dish can be coaxed to grow around these flexible scaffolds and meld with them, but this ‘cyborg’ tissue was created outside a living body. “The problem is, how do you get that into an existing brain?” says Lieber.
The team’s answer was to tightly roll up a 2D mesh a few centimetres wide and then use a needle just 100 micrometres in diameter to inject it directly into a target region through a hole in the top of the skull. The mesh unrolls to fill any small cavities and mingles with the tissue. Nanowires that poke out can be connected to a computer to take recordings and stimulate cells.
Using this technique, the researchers implanted meshes consisting of 16 electric elements into two different brain regions, enabling them to monitor and stimulate individual neurons. The researchers would like to scale up to hundreds of devices outfitted with different kinds of sensors. In the future, these arrays might be used to treat motor disorders, paralysis, and repair brain damage caused by stroke. What’s more, these implants could conceivably be used in other parts of the body. But before they get too carried away, the researchers will have to prove that the implantable technology is safe in the longterm.