Optimizing a novel nerve cuff electrode to record bidirectional neural activity*

Neural recordings can provide useful information regarding specific sensory or motor function that can be applied to functional electrical stimulation systems for persons with spinal cord injury or stroke patients. Among myriad neural interfaces, the nerve cuff electrode offers an attractive tool for communicating with peripheral nervous system. The tripolar cuff electrode is the most common nerve cuff design; however, the physical symmetry of this configuration does not allow for the differentiation of action potentials propagating in opposite directions (i.e., afferent vs. efferent activity). The main goal of this study was to test the feasibility of using a tetrapolar configuration to achieve high SNR, directionally-sensitive recording of nerve activity. The objectives for this design were to combine (1) low-noise recordings from two sets of tripolar contacts with (2) the directional information provided by differentially measuring the two tripolar signals.