Flexibility of Finger Activation Patterns Elicited through Non-invasive Multi-Electrode Nerve Stimulation

The inability to effectively activate and control skeletal muscles is a common impairment following a variety of neurological conditions or injuries. One common approach to restoring or augmenting this impairment is the use of external electrical stimulation of the muscles, called functional electrical stimulation (FES). Typically targeted directly at the anatomical muscle belly, existing methodologies often involve high current amplitudes, limited superficial muscle activation, and early onset of muscle fatigue. We have recently explored the capabilities of a non-invasive peripheral nerve stimulation method for the dexterous control of finger and hand muscles. Further development of our stimulation system has enabled us to manually search across a variety of stimulation locations with increased consistency and efficiency. This study examined the preliminary results in two subjects of an automated stimulation system which can rapidly characterize a large combination of stimulation electrodes. Our preliminary findings suggested that the stimulation grid was able to produce a number of clustered EMG activities and finger forces. This robust ability to flexibly generate different grasp patterns demonstrates the promise of the methodology in future applications for FES and rehabilitation.