A University of Iowa engineering professor is conducting research to make cochlear implants safer and enhance hearing quality by developing materials that will be more compatible and more effectively integrate with the human body.  

C. Allan Guymon, the Sharon K. Tinker Process Safety Professor of Chemical and Biochemical Engineering, has been working for years to improve the way the body responds to cochlear implants. These electronic devices help provide sound perception to those who are deaf or extremely hard-of-hearing. An external portion of the device sits behind the ear, while a second portion with electrodes that send impulses to nerve cells is surgically placed into the cochlea in the ear.  

The materials used to provide mechanical stability and flexibility critical to the long-term function of the implanted electrodes in the cochlea can lead to complications over time. The body recognizes the implant as foreign, leading to scarring and decreased hearing effectiveness. 

Working with Marlan R. Hansen, a professor of otolaryngology at the Carver College of Medicine, Guymon is using a new patented photochemical process to make coatings for existing implant systems using a class of materials called zwitterionic polymers.

These coatings show significant promise in making it much easier to implant the cochlear implant and minimize trauma during implantation. Additionally, the coating prevents build-up of proteins and cells on the implant surface leading to significantly reduced inflammation and scar formation.

By reducing trauma and scar tissue around the implant, electrical signals from the implant can more effectively reach nerve cells that transmit this information to the brain, dramatically increasing hearing capacity and quality for implant recipients. Ongoing work is focusing on further enhancing the mechanical stability and durability of the coated implant while reducing negative reactions from the human tissue when the implant is inserted. The coatings can also serve as reservoirs for therapeutic drugs that can provide additional benefits to implant patients.

While Guymon’s work focuses primarily on cochlear implants, being able to reduce scarring and trauma using these materials has far reaching implications for other biomedical implants ranging from catheters to tracheometry tubes to spinal cord stimulators. 

Guymon and Hansen were recently awarded a competitive renewal grant from the National Institutes of Health (NIH) to continue their ground breaking research. The NIH has awarded $560,110 for the first year of what is expected to be a $2.857 million, five-year project.  

Research reported in this publication was supported by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health under Award Number R01DC012578. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.