Manufacturing of a Reluctance Actuator for Use as a Hearing Implant in the Middle Ear

Within the realms of hearing loss and restorative technologies, developments of hearing aids for conductive hearing loss are especially demanding.Due to the constant medical interest in simplified implantation methods, the limited space in the middle ear and the simultaneous demand for an increased frequency range, there is a need for miniaturized and, at the same time, efficientactuators.Various magnetic concepts such as the balanced-armature principle, reluctance or magnetostrictive actuators can be applied here.The Institute of Micro Production Technology (IMPT)has expanded their research from the balanced armature principle to a reluctance concept. The advantage of a miniaturized reluctance actuator is the comparatively simple design with fewer components, which has a low degree of complexity. For a general comparison,a prototype of a reluctance actuatorwas designed, simulated and manufactured. A LaserDoppler Vibrometer was used to investigate the stiffness of the membrane, and the maximum displacement of the coupling rod, which transfers the mechanical displacement to the round window and thus sound waves to the inner ear.The results show, that the developed design enables a microactuator with a simpler structure, but could not maximize the displacement in the targeted specifications.