A Small Seismic Accelerometer Utilizing Single Crystal Piezoelectric Material

70490 Existing seismic transducers, needed for nuclear explosion monitoring, are not small, sensitive, rugged, or low enough in cost for deployment in large numbers. This project will develop a small seismic accelerometer using bulk piezocrystals to monitor and verify compliance with the Comprehensive Nuclear-Test-ban Treaty. Phase I will design and demonstrate the feasibility and advantages of a small seismic accelerometer exploiting high-coupling relaxor peizocrystals in their bulk form combined with the strain amplification of a Platform UniMorph Accelerometer. Mathematical modeling and finite element analysis will be used to determine the feasibility of building a small seismic accelerometer with the following specifications: (1) physical dimensions of 15 mm x 15 mm x 15 mm; (2) measurement range from 0.03Hz to 100 Hz; (3) full scale range of 0.5 g; (4) dynamic range of 160dB; (5) shock limits of 5g when operating, 200g non-operating; (6) temperature range from 0¿C to 50¿C; and (7) output sensitivity of 10 volts/g. Three mechanical prototypes will be built and demonstrated. Phase II will optimize the transducer design, provide signal conditioning electronics to compensate for thermal fluctuations in the PMNT, minimize power requirements, and develop approaches for automating the manufacture of the accelerometer. Commercial Applications and Other Benefits as described by the awardee: A single crystal-based small seismic accelerometer should have application to acoustic detection/ASW/military ship silencing machinery condition monitoring; intrusion detection; and seismic monitoring (DoD and commercial). In industrial markets, a small seismic accelerometer should provide possibilities for embedded use in active vibration cancellation for manufacturing machinery used in photolithography for integrated circuit manufacturing.