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 ¿s, exponential (90-10 percent) fall-times of 100-500 f4s 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.