Robotic Assistance for Cochlear Implants
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Public domain image from NIH Medical Arts.
The goal of this project is twofold: to improve the safety of cochlear implant procedures, and to improve the functionality of the implant. A cochlear implant is an array of electrodes surgically inserted into the cochlea. Its purpose is to recreate hearing in those who are deaf. During the implant surgery, there are a number of things that can go wrong. Even with successful implants, there is a lot of room for improvement, including inserting the implant deeper into the cochlear, which will lead to hearing lower-frequency tones, as well as curling the implant tighter around the nerve, which will result in better frequency discrimination as well as improved power efficiency.
Our goal is to use magnetic fields to steer the tip of the cochlear implant as it is inserted into the cochlea. The image of our experimental setup shown here shows one robotic stage that inserts a to-scale implant prototype into an Advanced Bionics to-scale cochlear implant phantom, as an ATI Nano17 force sensor measures the insertion force. A second robotic stage moves a large permanent magnet toward and away from the cochlea, as a motor rotates the magnet in sync with the implant insertion.
For cochlear-implant insertion experiments, such as in the development of the proposed magnetically steered implants, it is desirable to have a phantom scala tympani for laboratory experimentation. We have developed a model based on published anatomical data that can be used to create a scala-tympani phantom using a 3D printer. Images of our newest phantom, which can be made for both cochleostomy and round-window insertions, is shown below (shown with a Med-El practice electrode inserted). The complete description of the phantom's design were published in the Journal of Medical Devices in the paper "Scala-Tympani Phantom with Cochleostomy and Round-Window Openings for Cochlear-Implant Insertion Experiments". In this link we provide the high-definition .stl files (in a single .zip file) that we used to make the cochleostomy and round-window phantoms described in the paper. To anyone who would like to use these phantoms in their own work, we kindly ask that you provide a citation to the journal paper by Leon et al. that describes the phantom, and acknowledge this web page as the source of the files used to generate the phantoms.
The phantom design above replaces our original design, which is described below. We leave the files of the original design below for archival purposes only. A variety of improvements have been made over this original design, including more realistic surgical openings and more accurate channel dimensions, which are all documented in the newer submitted publication.
The results of the original design were published in the Journal of Medical Devices in the paper "A Scalable Model for Human Scala-Tympani Phantoms". Here is the Matlab file used to generate the model, as well as the SolidWorks model that can be used to create a 3:1 scale phantom. Our fabricated ST phantom is shown in the image.
Note: In our Matlab file, the ST cross-section profiles are exported to Excel (.xls) spreadsheets. After export, these files should be saved as tab-delimited text (.txt) files and then imported into SolidWorks as curves through XYZ points to allow creation of a lofted cut between the cross sections. A lofted cut cannot be created between the cross sections if they are imported into SolidWorks from .csv or .sldcrv files.
L. Leon, M. S. Cavilla, M. B. Doran, F. M. Warren, and J. J. Abbott, "Scala-Tympani Phantom with Cochleostomy and Round-Window Openings for Cochlear-Implant Insertion Experiments," J. Medical Devices, 8(041010):1-10, 2014.
J. R. Clark, L. Leon, F. M. Warren, and J. J. Abbott, "Magnetic Guidance of Cochlear Implants: Proof-of-Concept and Initial Feasibility Study," J. Medical Devices, 6(035002):1-8, 2012.
J. R. Clark, L. Leon, F. M. Warren, and J. J. Abbott, "Investigation of Magnetic Guidance of Cochlear Implants," IEEE/RSJ Int. Conf. Intelligent Robots and Systems, pp. 1321-1326, 2011.
J. R. Clark, F. M. Warren, and J. J. Abbott, "A Scalable Model for Human Scala-Tympani Phantoms," J. Medical Devices, 5(014501), 2011.
This material is based in part by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health under Grant 1R01DC013168, and in part upon work supported by the National Science Foundation under Grant No. 0952718. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Institutes of Health or the National Science Foundation.