And for the first time, a tetraplegic patient implanted with a set of neural probes and wearing an exoskeleton was able to walk and control both arms solely through brain control. The paper “An exoskeleton controlled by an epidural wireless brain–machine interface in a tetraplegic patient: a proof-of-concept demonstration” published in The Lancet Neurology journal describes a system driven via the long-term implant of a semi-invasive medical device dubbed Wimagine.
Developed at CEA in Grenoble, Wimagine collects brain signals in the sensorimotor cortex emitted when an individual imagines moving. Wimagine was designed for semi-invasive implantation in the cranium in order to record electrocorticograms (ECoG) over the long term using an array of 64 electrodes in contact with the dura mater. Electronic boards contain the electrocorticogram acquisition and digitalization systems, together with a remote power supply and wireless data-transfer systems via secure radio link to an external base station. The implant packaging was designed to ensure long-term biocompatibility and safety.
The major innovation in this device is its ability to provide chronic high-resolution recording of the brain’s electrical activity. This activity related to the moving intention is transmitted it in real-time wirelessly to a computer for decoding in order to control the movements of the exoskeleton’s four limbs. Hence a tetraplegic patient fitted with this neuroprosthetic implant can move by mentally controlling the exoskeleton, without external controls.
Decoding electrocorticograms required the development of highly sophisticated algorithms based on Artificial Intelligence methods and software to be able to control the movements of the exoskeleton in real-time. The Wimagine device also involved research engineers from CEA-List, the institute specialised in smart digital systems. These developed the four limb exoskeleton based on their reversible actuation and control-command bricks. This design specifically took into account the interaction of a quadriplegic person with the exoskeleton to be able to mobilize it safely.