Tiny ear implant could spell the end for costly hearing aids

At the heart of the device is an ultra small (1.2mm) electroacoustic transducer, which takes the form of a piezoelectric microactuator. Placed directly at the connection between the middle and inner ear, this transmits acoustic signals to the inner ear in the form of amplified mechanical vibrations, thereby enhancing the hearing capacity of patients. "The electroacoustic transducer works on the same principle as bending actuators," explained Dominik Kaltenbacher, an engineer from the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart "The bending elements, which are arranged in the shape of a pie, consist of a laminated composite made from piezoceramics and silicon. If voltage is applied, the elements bend upwards and generate a mechanical vibration. This spreads to the membrane of the round window and the inner ear, stimulating the auditory nerve." Despite the implant's small size, Kaltenbacher says it can output volumes of up to 120dB. "This high performance is necessary for good speech comprehension, particularly for high pitched sounds," he noted. The IPA team is currently testing a working prototype of the device. The first trials are planned for 2014.