PROGRESS IN THE DEVELOPMENT OF RUGGED LOW POWER COMPACT SILICON MEMS SENSORS FOR USE IN NUCLEAR EXPLOSION MONITORING

In this paper we present the results of our ongoing development of a family of high Q-factor in-plane microelectromechanical systems (MEMS) seismic sensors. We discuss the trade-offs in optimizing the performance for nuclear explosion monitoring. Three different geometries are presented with different optimizations of size versus predicted performance, shock, and vibration resistance. Two of these devices require a vacuum cavity within the device to obtain high Q-factors of the order of ~20,000, while the other device can work with a Q of ~500 that can be obtained in an unsealed cavity. Results of our initial evaluations of the Q obtainable under vacuum are presented showing that Q-factors in excess of 20,000 are obtainable. We also discuss the design and operation of the displacement transducers required for these devices. The transfer of the MEMS fabrication technology from a university to a commercial facility is discussed along with initial fabrication results from a 150mm wafer commercial process, including the formation of vacuum sealed cavities. 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies