Jan Scheuermann suffers from Spinocerebellar degeneration and is now unable to move her arms or legs. But after trials at Pittsburgh University she can now control a robotic arm through sensors attached to her brain.
The robotic arm is moved by a concept known as brain-computer interfacing. Sensors attached to the brain pick up neuron activity and translate these messages to the computer which signals the arm to move.
We record the signals from small groups of cells
Humans Invent tracked down Dr. Brian Wodlinger, who has been responsible for implementing the decoding algorithms and software used to control the arm, to find out how it works.
Wodlinger explains, “Essentially we have two electrode arrays that are implanted into the motor cortex and we record the signals from small groups of cells within this part of the brain.”
These sensors have hundreds of tiny needles that pick up the electricity of a few hundred neurons located in this part of the brain.
Though there are other studies involving patients moving a robotic arm by thought, such as the BrainGate study at Brown University, this is probably the most sophisticated prosthesis in terms of its ability to control and manoeuvre objects.
Wodlinger says, “It has several very interesting features. First of all, it has more degrees of freedom so it can articulate in many more ways than other arms in the past. Also, the fingers are almost soft if you push against them, unlike a normal robot’s which are usually stiff. They have what is called an impedance control.”
Scheuermann proved a quick learner and within a matter of weeks was able to move the arm and clasp onto objects.
There are sensors on the hand that can determine pressure for touch
Wodlinger says, “She was able to move around in three dimensions on the second day of testing which was quite extraordinary. It took about 13 weeks for her to really achieve her best control so there was is a very nice learning curve even though it did start off quite high.”
Scheuermann is now able to feed herself with the robotic arm as demonstrated in the video below.
The next step is to perfect the control of the hand. Wodlinger says, “Obviously we would like to get better control of the hand even though it is already fairly advanced. It has individual control of each finger, there are sensors on the hand that can determine pressure for touch but we would really like to improve the number of hand grasps that can be controlled and perhaps, in the longer term, give feedback into the sensory cortex about the actual touch sensors on the hand.”
If this can be achieved then the patient might be able to restore a sense of touch through the prosthetic limb. Currently however, these tests have only been carried out in the laboratory but the idea is to attach the robotic arm to Scheuermann’s wheelchair in due course.
Wodlinger believes we are still a few years off from seeing this sort of technology used outside of the laboratory. He says, “I think we are probably about 10 years out. It hasn’t really begun the process of commercialization yet.”
Though still in the trial phase, it is exciting to see this type of technology progressing well in what could prove to transform the quality of life for both patients with paralysis and amputees.