Nanotubes Gentler On Brain Tissue

Engineers and scientists at Rice University have developed carbon nanotube electrodes, microfluidic devices, microelectrodes for a more gentle implantation. The nanotubes are flexible, researchers have developed a method in which to implant them into brain tissue. They may help with neurological diseases and aid with scientists’ exploration of the cognitive processes. This promising technology appears published in the American Chemical Society.

This technique is based on using microfluidics, which shows promise in improving therapies that rely on electrodes to trigger actions and sense neuronal signal in patients with conditions such as epilepsy and others. According to the team this process could help to discover the mechanisms behind cognitive processes. The use of this process may also help to create direct interfaces with the brain to could allow patients possible abilities to control artificial limbs, see, and hear.

This process uses the force applied by fast moving fluids that gently pull along the insulated flexible fibres forward into the brain tissues without buckling. This delivery method could possibly replace hard shuttles or the stiff biodegradable sheaths that are currently used to deliver wires into the brain tissue Both of the current methods can damage the sensitive brain tissue along the way.

Vivo experiments and in lab have shown how the devices force a viscous fluid to flow around the thin fiber electrode. The fast moving fluids slowly pull it, advancing it through a small aperture leading to the tissue. Once the fiber crosses into the tissue tests have shown the flexible wire will stay straight.

The fibre moves slowly compared to the rate of the speed of the fluid. But it is not pushed on at the end of the wire or at an individual location which is the important thing, it’s being pulled along the entire cross section of electrode completely distributing the force, says Caleb Kemere.

It’s like trying to put a wet noodle into Jello, alone it doesn’t work, but put the noodle under running water, and it will, as the water will pull it straight through, says Jacob Robinson.

The insulated flexible fibre moves gently through an aperture that is close to 3 times its size, but  that still remains small enough as to let little of the fluid through. According to Robinson experiments show that none of the fluids follow the fibre into the brain tissue.

A small gap between the tissue and device the fibre is in that keeps it on course. The short length allows for the penetration into the brain tissue, using the fluid flow on the back end to keep the insulated fibre stiff as it advances forward and down into the brain tissue. Once into the tissue, it is into an elastic matrix supported by the gel like material all around where it is supported laterally and bucking can not happen easily, says Robinson and Pasquali.

Electrons are conducted in every direction by the carbon nanotube fibres, to communicate with neurons they can be conductive at the tip only, says Kemere.  Adding, insulation is taken for granted. It seemed nontrivial to coat the nanotubes with something that maintains integrity and blocks ions from coming in.

Researchers are hopeful that this technology may eventually be scaled to deliver multiple microelectrodes at once into the brain tissue that are closely packed, as this process creates less damage, making it easier to embed implants.