An Asymmetric Two Electrode Cuf for Generation of Unidirectionally Propagated Action Potentials

An asymmetric two electrode cuff (ATEC) for generation of unidirectionally propagated action potentials (UPAP's) has been tested in animals. Results indicate that the design is well suited for applications of "collision block" of peripheral nerve transmission. This electrode cuff differs from a standard bipolar electrode cuff in that the anode is enclosed by an insulating sheath of larger diameter than the cuff's cathode and the electrodes are asymmetrically placed within the cuff. In all 13 animals studied, ATEC's with anodes of 1.6 or 3.4 mm diameter and with cathodes of 1.2 mm diameter generated UPAP's when used on a nerve trunk of approximately 1 mm diameter. The cuff length used was 16 mm and the cuff length asymmetry (i. e., distance from cathode to proximal end over distance from cathode to distal end) was 1.7:1. Stimuli were regulated-current rectangular pulses with exponential trailing phases. For pulse widths of 100-500 μs, exponential (90-10 percent) fall-times of 100-500 μs minimized total charge injection. The virtual cathode excitation typically seen in standard bipolar electrode cuffs was always adequately suppressed with the ATEC configuration. ATEC's generated UPAP's over a larger window of current amplitudes than monopolar electrodes of similar dimensions.