Shape memory alloy coil training toward guided electrode array insertion in cochlear implants

Abstract Current cochlear implant technology has limited capability to both safely insert the electrode array fully to the apex of the cochlea and laterally position the array precisely within the cochlea. The use of a programmable shape memory alloy guidewire has the potential to improve both electrode insertion depth and lateral placement control. The purpose of this study was to quantify the difference between trained and activated shapes of electrically actuated small-diameter Nitinol wires and thereby to refine a wire training methodology. Nitinol wires with 50–250 µm diameters were trained to form a coil shape, with training time varying from 30 s to 10 min. Measurements were taken at the training, activation, and relaxation stages of the wire. To obtain consistent coil shape, larger-diameter (150–250 µm) wires typically require 6 min of training time, while smaller-diameter (50–100 µm) wires require a longer training time, approximately 10 min. Graphical abstract