Directional microphone based on artificial spider silk

Abstract

Directional sound detection is usually achieved by using pressure microphone arrays. The drawback of such arrays is that they need further signal processing and show difficulties in combining high sensitivity, flat bandwidth and compactness. To counter these disadvantages spider silk microphones have shown to be very efficient at capturing the fluctuations in air velocity with a figure-of-eight directivity, high sensitivity and a broad frequency response. To create an artificial sensor based on this concept, silicon nitride (SiNx) was used. Even though the SiNx-samples have a high pre-stress they show high sensitivity and in average a figure-of-eight characteristic. In combination with a laser vibrometer it was shown that this setup is a fully functioning microphone. Yet there is plenty of space for improvement. Reduction in internal stress and a portable transduction setup are upcoming challenges for SiNx-fiber sensors.