One of the stumbling blocks being faced by the development of bionic prosthetics is the difficulty of developing a method of controlling an artificial limb, especially in a manner that would seem natural to the wearer. Advances in creating brain-machine interfaces have seen major advancements in recent years, but are still hampered by the difficulty of picking up the brain’s faint signals by sensors placed on the scalp.

Stronger signals can be received if the sensors are placed directly on (or in) the brain, but that method requires invasive, and potentially dangerous brain surgery. However, a new implant inserted through the subject’s blood vessels might help reduce the risk of inserting such implants.

In a DARPA-funded experiment conducted by the University of Melbourne’s Vascular Bionics Laboratory, a small endovascular stent, embedded with electrodes, was inserted into a cortical vein connected to the motor center of the brain of a sheep, where it was able to make reliable recordings of the sheep’s motor functions for 190 days.

This stent/electrode, or "stentrode", was inserted into the vein via a blood vessel in the sheep’s neck, eliminating the need to open the subject’s skull to implant the device. The 15mm (0.6 inch) device consists of a self-expanding mesh, delivered to the site through a delivery catheter. Embedded with small, passive electrodes, the device unfolds itself, anchoring itself to the blood vessel’s wall, where the electrodes can pick up on nearby electrical impulses generated by the brain’s neurons. The research team hopes to start testing the new device on human subjects sometime in 2017. 

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