The mechanical properties of cochlear fresh basilar membrane in miniature pigs

This study investigates miniature pig basilar membrane (BM) biomechanics to optimize cochlear implant electrode design and surgical safety. Using 16 miniature pig cochleae, BM rupture force and Young's modulus were evaluated via nanoindentation and rupture testing. A 90 µm probe advanced at 0.1 mm/s recorded force-displacement curves, while nanoindentation measured elasticity at four cochlear angles (90°, 180°, 270°, 360°). Rupture forces varied significantly across regions: median values were 56 mN (90°), 27.5 mN (180°), and 20 mN (270°), with extremes of 120 mN (90°) and 9 mN (270°), indicating heightened distal fragility. Young's modulus followed analogous trends, showing medians of 1.53 MPa (90°), 1.41 MPa (180°), 1.65 MPa (270°), and 1.30 MPa (360°). Both metrics decreased distally, reflecting progressive BM flexibility and susceptibility to insertion trauma. These results highlight the need for electrode designs that reduce insertion forces in vulnerable distal regions to preserve residual hearing. The biomechanical dataset provides critical benchmarks for refining surgical protocols and developing automated/robotic electrode insertion systems, prioritizing minimal mechanical trauma. This work advances strategies for safer cochlear implantation by aligning electrode mechanical properties with region-specific BM thresholds.