![]() Pursuing such an alternative we investigated flexible, biocompatible polyimide based TFAs for intracochlear stimulation. Given the stiffness of the silicon-based TFAs, a flexible TFA alternative is essential. However, such arrays have proven difficult to insert and accurately place in the lower chamber (scala tympani) during acute in vivo studies. The efficacy of a silicon-based TFA for intracochlear stimulation has been reported in animal models. One such example is the cochlea: the average human cochlea rotates through two and one half turns from base to apex and is comprised of three chambers, or scala. While the availability of commercial TFAs alleviates the time-consuming burden of fabrication, many in vivo applications require some amount of postprocessing to enable a TFA to physically approach anatomic structures. Primarily based on silicon or polyimide substrates, these arrays can be custom-designed or selected from a design library, for neurophysiological studies. The ongoing validation, as well as the need, of multisite TFAs has ultimately led to the commercial availability of lithographically defined, batch-processed arrays (Neural Nexus Technologies, Ann Arbor, MI). Serving as an essential interface between the nervous system and microelectronics, TFAs have enabled a greater understanding of electrical and chemical signaling in the brain, as well as a therapeutic option for overcoming sensory loss in the auditory and visual systems. By layering and patterning dielectrics and conductors upon such substrates, multisite stimulating and recording electrode arrays have been realized with submicron precision. Through the utilization of integrated circuit fabrication methods, TFAs have been developed on a variety of substrates including sapphire, metal, glass, silicon, and polymers. Since their introduction in the mid 1970s planar thin-film arrays (TFAs) have become an invaluable scientific tool for systems neurophysiology. Our method combines the utility of readily available commercial devices with a straightforward postprocessing step on the order of 24 hours. Using microcomputed tomography imaging (50 μm resolution), distances ranging from 100 to 565 μm from the cochlea's central modiolus were measured. A total of 10 arrays were each inserted through a round window approach into the cochlea's basal turn of eight felines with one delamination occurring upon insertion (preliminary results of the in vivo data presented at the 48th Annual Meeting American Neurotology Society, Orlando, FL, April 2013, and reported in Van Beek-King 2014). We report an average intracochlear stimulating current threshold of 170 ± 93 μA to evoke an auditory brainstem response in 7 acutely deafened felines. Each array supported 20 platinum sites (180 μm dia., 250 μm pitch), spanning nearly 28 mm in length and 400 μm in width. Additional silicone was applied to the tip to protect neural tissue during insertion and along the array to improve surgical handling. Using a pneumatically driven dispensing system, an average 232 ± 64 μm (mean ± SD) thickness layer of silicone adhesive coating was applied to stiffen the underside of polyimide multisite arrays. 2010.We present an effective method for tailoring the flexibility of a commercial thin-film polymer electrode array for intracochlear electrical stimulation. Heiberg, “Figure 2”, Researchgate, Available online at, Annotated-screen-shot-of-the-main-user-interface-of-Segment-The-circles-indicate_fig1_4090686, Jan.“High-Resolution Cardiac Imaging”, Biomedial Physics Research Group, Available Online at,, Mar.“Discover OsiriX MD The World Famous Medical Imaging Viewer”, OsiriX, Available Online at, Apr. ![]()
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