An active surgical positioning device for a cochlear implant electrode array

Cochlear implants have been of great benefit in restoring auditory function to individuals with profound bilateral sensorineural deafness. The implants are used to directly stimulate auditory nerves and send a signal to the brain that is then interpreted as sound. This project focuses on the development of a surgical position tool to accurately and effectively place an array of stimulating electrodes deep within the cochlea. This will lead to improved efficiency and performance of the stimulating electrodes, reduced surgical trauma to the cochlea, and as a result improved overall performance to the implant recipient.; The positioning tool reported here consists of multiple fluidic chambers providing localized curvature control along the length of the attached silicon electrode array. The chambers consist of 200mum inner diameter PET(polyethylene therephthalate) tubes with 4mum wall thickness. The chambers are molded in a tapered helical configuration to correspond to the cochlear shape upon relaxation of the actuators. This ensures that the optimal electrode placement within the cochlea is retained after the positioning tool becomes dormant (for chronic implants).; Actuation is achieved by injecting fluid into the PET chambers and regulating the fluidic pressure. The chambers are arranged in a stacked, overlapping design to provide fluid connectivity with the non-implantable pressure controller and allow for local curvature control of the device. The stacked tube configuration allows for localized curvature control of various areas along the length of the electrode and additional stiffening and actuating power towards the base. Curvature is affected along the entire length of a chamber and the result is cumulative in sections of multiple chambers. The actuating chambers are bonded to the back of a silicon electrode array.; Summary of results. (1) A manufacturing process for multiple chamber insertion tools has been developed and prototypes have been fabricated at several scales. (2) Testing cavities for insertion tests of the tool have been fabricated at several scales. (3) Insertion tests have been done that demonstrate that this type of actuation is appropricate for a cochlear insertion tool. (4) The tool has been integrated with both a high density silicon electrode array and an electrokinetic pump. (5) A predictive theory combining FEA results and mathematical models has been developed for the actuation of the chambers. (6) A lithographic process to build the insertion tool has been developed and tested to improve the performance and manufacturability of the tool.