Computational and Mathematical Methods in Medicine
Volume 2013 (2013), Article ID 250915, 9 pages
Modiolus-Hugging Intracochlear Electrode Array with Shape Memory Alloy
1School of Electrical Engineering & Computer Science, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 110-742, Republic of Korea
2Department of Electronics Engineering, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Republic of Korea
3Department of Brain & Cognitive Sciences, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Republic of Korea
4Cognitive and Neural Systems, Boston University, 677 Beacon Street, Boston, MA 02215, USA
Received 11 February 2013; Revised 15 April 2013; Accepted 15 April 2013
Academic Editor: Chang-Hwan Im
Copyright © 2013 Kyou Sik Min et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
In the cochlear implant system, the distance between spiral ganglia and the electrodes within the volume of the scala tympani cavity significantly affects the efficiency of the electrical stimulation in terms of the threshold current level and spatial selectivity. Because the spiral ganglia are situated inside the modiolus, the central axis of the cochlea, it is desirable that the electrode array hugs the modiolus to minimize the distance between the electrodes and the ganglia. In the present study, we propose a shape-memory-alloy-(SMA-) embedded intracochlear electrode which gives a straight electrode a curved modiolus-hugging shape using the restoration force of the SMA as triggered by resistive heating after insertion into the cochlea. An eight-channel ball-type electrode array is fabricated with an embedded titanium-nickel SMA backbone wire. It is demonstrated that the electrode array changes its shape in a transparent plastic human cochlear model. To verify the safe insertion of the electrode array into the human cochlea, the contact pressures during insertion at the electrode tip and the contact pressures over the electrode length after insertion were calculated using a 3D finite element analysis. The results indicate that the SMA-embedded electrode is functionally and mechanically feasible for clinical applications.