Biocompatible membrane of PDMS for the new chamber prosthesis stapes.

Stapes protheses are designed for patients with otosclerosis resulting immobilization or significant reduction of the stapes mobility. All currently used prostheses are called - piston prosthesis. However, its use to stimulate the cochlea is still imperfect. New chamber stapes prosthesis allows the perilymph excitation more effective than the piston prothesis. Moreover, the chamber prosthesis eliminates the common causes of piston-stapedotomy failures. The most important element of the new prosthesis is a flexible membrane. The membrane stiffness should be close to the stiffness of normal annular ligament. This work presents the process of selection of the membrane's thickness and its manufacturing technology. Method A 3D model of the chamber stapes prosthesis was build using Autodesk Inventor 2015. The model was imported to Abacus 6.13 computing environment. During numerical simulations, displacements corresponding to applied loads were calculated and the membrane thickness was adjusted so that its stiffness was the same as the ligament stiffness (~ 120 N/m). The compliance ratios calculated from the load-displacement curves for the membrane and the annular ligament were verified using linear regression analysis. After determining the thickness, the manufacturing technology of the membrane was developed. Results The best similarity between the membrane's and annular ligament's stiffness was achieved for PDMS membrane with the 0,15- mm thickness (similarity ratio R2=0,997752). In this work, the technological parameters of spin-coating process for membrane manufacture are also presented. Summary The proper functioning of the chamber stapes prosthesis requires the PDMS membrane with a thickness of 0,15 mm. The 0,15-mm membrane has the tiffness close to the stiffness of the normal annular ligament. Therefore, the chamber stapes prosthesis provides the perilymph stimulation at the level comparable to the healthy ear. New prosthesis is currently under pre-clinical investigation to optimize the shape of the inner chamber's surface.