Frictional Behavior of Cochlea Electrode Array is dictated by Insertion Speed and impacts Insertion Force

摘要

During electrode array insertion while cochlear implantation, the electrode array has friction with the sensitive endocochlear lining and causes mutual mechanical trauma. Both, the impact of insertion speed on electrode friction and the relationship between electrode insertion force and friction has not been investigated yet. In this study, friction forces and coefficients between a 31.5 mm standard cochlear electrode array and endocochlear lining mimicking tissue have been acquired, depending on different insertion speeds (0.1, 0.5, 1.0, 1.5 and 2.0 mm/s). Additionally, the electrode insertion forces during the placing into a scala tympani model were recorded and correlated with the friction coefficient. Within these experiments the lowest friction coefficient occurs at 0.1 mm/s (0.24 ± 0.13), rises to a maximum at 1.5 mm/s (0.59 ± 0.12) and falls again at 2 mm/s (0.45 ± 0.11). Similar patterns were observed for recorded insertion forces. Consequently, a high correlation coefficient (0.9) between the insertion force and friction coefficient was calculated. The present study reveals a non-linear increase in electrode array friction, when insertion speed raises, and reports a high correlation between friction and electrode insertion force. Knowledge of this parameters is important for the assessment of intracochlear trauma and for future robotic insertion of electrode arrays.