- A wide range of hand and arm orientations can be achieved just by thinking of the desired movement (Image: Journal of Neural Engineering/IOP Publishing)
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A woman paralysed from the neck down can now grab a ball with a robotic arm – just by thinking about it.
Jan Scheuermann, who lost control of her limbs in 2003, was able to make complex hand movements using the robot arm. She successfully picked up and moved a variety of objects, from a tiny cube to a tube standing upright (see video).
The system, developed byJennifer Collinger at the University of Pittsburgh, Pennsylvania, and colleagues, uses two small electrode grids implanted in Scheuermann's brain, in the region of the left motor cortex responsible for controlling her right arm and hand. The devices were connected to a computer, which analysed electrical brain activity picked up by 96 contact points within the grids.
Computer algorithms learned to match the electrical patterns to Scheuermann's thoughts about making specific movements with a hand or arm. These patterns were then translated into the real movements of a robotic arm.
The latest version of the algorithm can detect four patterns of activity related to the shape of the hand, adding a scooping shape, thumb extension and a pinching action to the repertoire of possible movements. The improvements allow Scheuermann to control the artificial limb with 10 degrees of freedom simultaneously.
The team say that such a wide range of motion has never been achieved in this way before. They hope that adding the capacity to use different hand shapes will expand the range of activities paralysed people can perform independently – from gestures to manipulation of objects – once the technology moves outside the lab.
Journal reference: Journal of Neural Engineering, DOI: 10.1088/1741-2552/12/1/016011