Micromachined Infrasound Sensors

The Ground-based Nuclear Detonation Detection Research and Development office seeks advanced technology for the monitoring of explosion events using infrasonic signatures. In this STTR, Silicon Audio, Inc. and The University of Texas at Austin will team together to develop an advanced microelectromechanical-system MEMS) based piezoelectric infrasonic-sensor technology. The sensor will aim to exceed all of the threshold specifications important for explosion and treaty-monitoring applications, while at the same time focusing on robustness against wind noise so that ultimately a compact sensor system may be realized. The developed sensor will be ideal for large distributed arrays, which have potential advantages in some scenarios including ease of installation, portability, and versatility with respect to enabling innovative data-processing. In Phase I, we aim to develop a micromachined piezoelectric transducer node that has ultra-low noise, below 10-8 Pa2/Hz noise spectral density across the majority of the 0.01 10-Hz monitoring bandwidth. Highlights of the sensor construction include a unique wafer-bonding construction, and the integration of a mechanical-acoustical band-limiting filter prior to transduction. In Phase II, we aim to develop a digital version of the sensor node to interface with a telemetry system for a large-array demonstration. The commercial feasibility of a sound-intensity digital-sensor node will also be investigated in Phase II. The proposed sensor development aims to make a contribution to the field of infrasonic monitoring by making commercially available an ultra-low-noise sensor element. The dominant benefit of the proposed work is increased public safety that results from accurately monitoring explosions and gathering intelligence regarding rogue testing activities. The sensor development will also benefit scientific applications, including the study of volcanoes, earthquakes, tsunamis, and various atmospheric phenomena.