Parametric Modeling of Cochlear Electrode Arrays Using Design of Experiments and Finite Element Analysis (FEA).

Abstract

Cochlear implant (CI) electrode arrays must navigate the delicate, spiraling microanatomy of the human cochlea. Optimizing their intrinsic mechanical properties is crucial for ensuring smooth surgical insertion and preventing extracochlear buckling. This study presents a parametric, bench-type biomechanical evaluation of tapered cochlear electrode arrays, combining three-dimensional (3D) finite element analysis (FEA) with a design of experiments (DOE) methodology. The array was modeled as a heterogeneous composite, comprising platinum-iridium (Pt-Ir) conductors embedded in a polydimethylsiloxane (PDMS) (silicone) matrix and evaluated as a free-space cantilever under simulated surgical deflection conditions of up to 30°. This approach isolates the intrinsic bending stiffness and longitudinal column strength independent of complex tribological friction. A 15-run factorial design varying apical radius, basal radius, and array length was utilized to quantify their interactive effects on tip deflection and reaction force. The FEA results demonstrated that across the parametric sweeps, maximum tip deflection ranged from 6.16 to 8.27 mm, while the reaction force varied between 1.096 and 4.66 mN. Peak Von Mises stress localized at the fixed basal end at 205.86 MPa, operating safely within the elastic limit of the composite's alloy. Analysis of variance (ANOVA) revealed that array length is the dominant driver of tip deflection, whereas the basal radius governs reaction force due to its fourth-power scaling of the area moment of inertia. Predictive regression models achieved adjusted R-squared values approaching unity; as the experimental runs are derived from deterministic FEA simulations rather than stochastic physical trials, this near-perfect fit reflects exact mathematical mapping of the response surface rather than real-world physical variance. To validate this deterministic numerical framework, the outputs were successfully correlated against previously published experimental data using optical fibers as structural proxies under precision force measurement. Ultimately, these findings provide an efficient, predictive parametric design framework for benchmarking and comparing tapered electrode array geometries, utilizing flexural rigidity and reaction forces as fundamental proxies for safe surgical handling and structural trackability.