A neuroprosthesis is a tool to overcome grasping difficulties after a spinal cord injury. In healthy persons the upper limb function, like lifting the hand is controlled intuitively. The command to lift the hand is generated by dedicated neurons in the motor cortex and is passed through the spinal cord to the nerve of the target muscle, which contracts and performs the desired movement (left person in the figure). After a high spinal cord injury the signal cannot be transferred anymore through the spinal cord and no movement is performed (middle person in the figure). The neuroprosthesis system bypasses the lesion site by recording and decoding the movement intention on the brain or using residual muscular functions. These signals are integrated in a computer that generatres an appropriate grasp pattern, which is applied to the muscles by Functional Electrical Stimulation (FES) resulting in the intended movement (right person in figure).
Currently, this system is used in a clinical setting to restore two grasp patterns by placing seven electrodes manually on the lower arm (see video). However, in daily living issues like missing reproducibility of electrode placement and grasp force variability when rotating the arm occur. To overcome these problems a multiple surface electrode array will be engineered (see figure X(figure from proposal)) and tested.
Patrick Ofner is a project scientist and PhD candidate at Graz BCI-LAB (TUG).
In this introductory video he explains the principle of functional electric stimulation (FES), a technology which will be incorporated and further developed in the MoreGrasp project. Watch this video to learn more about the technolgy!