TY - JOUR
T1 - Modeling Intracochlear Magnetic Stimulation
T2 - A Finite-Element Analysis
AU - Mukesh, S.
AU - Blake, D. T.
AU - McKinnon, B. J.
AU - Bhatti, P. T.
N1 - Funding Information:
The authors would like to acknowledge and thank the Augusta University Veterinary Staff and Paul Spurlock, DVM, as well as MED-EL (Medical Electronics, GmbH, Innsbruck, Austria) for an unrestricted educational grant. They would also like to thank Georgia Institute of Technology graduate students W. Waheed for assistance with post-processing of COMSOL results, and J. Yao for editorial contributions. Finally, the authors thank the anonymous reviewers for their important comments that served to strengthen the work presented.
Funding Information:
Manuscript received April 19, 2016; revised August 10, 2016; accepted October 15, 2016. Date of publication November 2, 2016; date of current version August 7, 2017. This work was supported in part by the National Science Foundation under Grants CBET-1133625, and CAREER ECCS-1055801, and the National Center for Advancing Translational Sciences of the National Institutes of Health under Award UL1TR000454. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Publisher Copyright:
© 2017 IEEE.
PY - 2017/8
Y1 - 2017/8
N2 - This study models induced electric fields, and their gradient, produced by pulsatile current stimulation of submillimeter inductors for cochlear implantation. Using finite-element analysis, the lower chamber of the cochlea, scala tympani, is modeled as a cylindrical structure filled with perilymph bounded by tissue, bone, and cochlear neural elements. Single inductors as well as an array of inductors are modeled. The coil strength (100 nH) and excitation parameters (peak current of 1-5 A, voltages of 16-20 V) are based on a formative feasibility study conducted by our group. In that study, intracochlear micromagnetic stimulation achieved auditory activation as measured through the auditory brainstem response in a feline model. With respect to the finite element simulations, axial symmetry of the inductor geometry is exploited to improve computation time. It is verified that the inductor coil orientation greatly affects the strength of the induced electric field and thereby the ability to affect the transmembrane potential of nearby neural elements. Furthermore, upon comparing an array of micro-inductors with a typical multi-site electrode array, magnetically excited arrays retain greater focus in terms of the gradient of induced electric fields. Once combined with further in vivo analysis, this modeling study may enable further exploration of the mechanism of magnetically induced, and focused neural stimulation.
AB - This study models induced electric fields, and their gradient, produced by pulsatile current stimulation of submillimeter inductors for cochlear implantation. Using finite-element analysis, the lower chamber of the cochlea, scala tympani, is modeled as a cylindrical structure filled with perilymph bounded by tissue, bone, and cochlear neural elements. Single inductors as well as an array of inductors are modeled. The coil strength (100 nH) and excitation parameters (peak current of 1-5 A, voltages of 16-20 V) are based on a formative feasibility study conducted by our group. In that study, intracochlear micromagnetic stimulation achieved auditory activation as measured through the auditory brainstem response in a feline model. With respect to the finite element simulations, axial symmetry of the inductor geometry is exploited to improve computation time. It is verified that the inductor coil orientation greatly affects the strength of the induced electric field and thereby the ability to affect the transmembrane potential of nearby neural elements. Furthermore, upon comparing an array of micro-inductors with a typical multi-site electrode array, magnetically excited arrays retain greater focus in terms of the gradient of induced electric fields. Once combined with further in vivo analysis, this modeling study may enable further exploration of the mechanism of magnetically induced, and focused neural stimulation.
KW - Cochlea
KW - cochlear implants
KW - finite-element analysis
KW - induced electric fields
KW - submillimeter inductors
UR - http://www.scopus.com/inward/record.url?scp=85029166851&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85029166851&partnerID=8YFLogxK
U2 - 10.1109/TNSRE.2016.2624275
DO - 10.1109/TNSRE.2016.2624275
M3 - Article
C2 - 27831887
AN - SCOPUS:85029166851
SN - 1534-4320
VL - 25
SP - 1353
EP - 1362
JO - IEEE Transactions on Neural Systems and Rehabilitation Engineering
JF - IEEE Transactions on Neural Systems and Rehabilitation Engineering
IS - 8
M1 - 7731169
ER -