Hironosuke Ikeda

Development of an Implantable Hearing aid Using a Piezoelectric Vibrator of Bimorph Design: State of the Art

A new, implantable hearing aid has been developed. An ultraminiature electret microphone placed under the skin of the external ear canal transduces sound waves into electrical impulses that are amplified with battery power. The amplified electrical impulses are fed into a piezoelectric vibrator directly in contact with the stapes. The vibrator transduces the electrical impulses into mechanical vibration with minimal consumption of electrical energy. Direct coupling of the vibrator to the stapes allows a high degree of fidelity in the perception of sound. The developmental process and the structure and function of each component are described together with clinical problems. Preliminary and tentative implantation of this new device during middle ear surgery indicated that it would be beneficial to patients who have suffered hearing loss from middle ear disease and whose condition does not lend itself to surgical correction.

Behaviour of various cathode materials for non-aqueous lithium cells

Abstract The reaction mechanisms with Li of various metal oxides, sulfides and a selenide in nonaqueous electrolyte have been studied by the galvanostatic method, X-ray diffraction analysis, and ion-microanalysis. As a result, cell reactions were classified into 3 types. (1) The directly reduced type: cathode materials are reduced directly to metal; CuO, etc. (2) The 2 step reaction type: reaction proceeds through intermediate products: FeS 2 (3) The solid diffusion type, based on the so-called intercalation reaction; MnO 2 , TiS 2 , etc.