Novel designs for middle ear implants produced by micro injection molding

State-of-the-art middle ear implants feature neither the required adaptivity in length to compensate changes of air pressure nor a damping function to prevent harm caused by excessive acoustic pressure. A new design for middle ear implants, composed of several integral hinges and produced by micro injection molding (MIM) resolves this limitation. Several designs were developed and simulated under static load, equivalent to a sound pressure level (SPL) of 90 dB (0,632 Pa) respectively 153 dB (1000 Pa), using finite element method. The deformation was recorded to determine spring stiffness. Using the new design and establishing PEEK as material, a spring stiffness of 3150 N/m at a load of 90 dB and 2570 N/m at 153 dB respectively could be achieved easily. With the first resonance frequency at 8800 Hz, a stiff structure for good transmission of sound can be obtained and the dimensions of 6×2×1.2 mm are compatible with common surgical techniques. MIM in combination with PEEK shows to be a well suited method to produce novel designs for middle ear implants that feature requirements that common designs fail to provide.