Measurement of directivity for the design of an implantable microphone implanted under an artificial skin model

A microphone implanted under the skin became a significant issue owing to the advent of fully-implantable hearing aids (F-IHAs). And, the design of implantable microphone is needed to be considered the biocompatibility, effects of the human skin and directivity. However, there were few studies to develop implantable microphone to consider directivity. In this paper, to design and implement the implantable microphone for the F-IHA, the directivity of the implantable microphone placed under an artificial skin model was measured. The artificial skin used the test model was made by a gelatin gel that was normally studied as soft tissue model of an ultra-sound phantom. And acoustic properties of the test model skin are similar to it of rats that are the transmission loss and the absorption coefficient.