In order to place electrodes deep into the brain without disrupting too much tissue, they must be stiff and as narrow as possible. There are a number of recently developed materials that are incredibly narrow and electrically conductive, such as carbon nanotubes and graphene, but they’re quite pliable when made at scales of a few millimiters. Because of how soft they are, before pushing them into the brain, they have to be coated with another material to make them stiffer. Stiffening agents increase the size of the electrodes and then have to dissolve or be removed in some other way to achieve the best results, which are big hassles and limitations. Now researchers at Rice University are reporting on an unusual device they developed that can push soft, very narrow electrodes into brain tissue without having to stiffen them first.
The researchers compare this to advancing a wet noodle into Jell-O. But, instead of pushing, they’re actually pulling on the “noodle”. The long piece of carbon nanotube, for example, is positioned inside a special microfluidic chamber that propels liquid along the length of the material and toward the exit of channel. The liquid is propelled quite intensely against the fiber inside the device, which actually seems to stiffen the material along the entire length of the fiber, even what’s outside the device. The researchers explain that the fiber is actually pulled rather than pushed, which helps to avoid buckling and effectively stiffening the fiber along its entire length.
Take a look at the following couple videos showing off how a soft fiber is pushed into a block of gelatin:
Study in Nano Letters: Fluidic Microactuation of Flexible Electrodes for Neural Recording…
Via: Rice…