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Novel Ultrasensitive Magnetic Field Sensors for Earthquake Early Warning Systems and Medical Imaging Gopalan Srinivasan, Oakland University, DMR 0902701.

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  1. Novel Ultrasensitive Magnetic Field Sensors for Earthquake Early Warning Systems and Medical ImagingGopalan Srinivasan, Oakland University, DMR 0902701 The research focuses on materials capable of converting hard-to-measure magnetic field to an easy-to-measure voltage. The composites have two phases, one that responds to a magnetic field by changing its shape and a second phase that converts this shape change to voltage. The primary objective is to obtain new composites that are capable of measuring extremely small magnetic fields that are a billion time smaller than the Earth’s magnetic field. Efforts during the past year resulted in a new family of highly efficient ultrasensitive composites with piezoelectrics such as langatate or quartz and ferromagnetic alloys. The composites are superior to traditional ferroelectric based composites and are capable of measuring pico-Tesla fields. Fig.1: Data showing conversion of magnetic-to-electrical field (voltage) in a composite of piezoelectric langatate (LGT) and permendur (P) which is a ferromagnetic alloy. The LGT-P sample is exposed to a magnetic field and the composite in turn produces a voltage. The LGT-P composite shows a much higher field conversion efficiency compared to traditional composites with ferroelectric PZT or PMN-PT. Appl. Phys. Lett. 100, 052901 (2012)

  2. Novel Ultrasensitive Magnetic Field Sensors for Earthquake Early Warning Systems and Medical Imaging Gopalan Srinivasan, Oakland University, DMR 0902701 The miniature, inexpensive composite sensors developed under this program have the potential to replace expensive, bulky SQUID sensors for use in magneto-cardiography (MCG). An array of the composites could function as an early warning system for earthquakes. Low-frequency magnetic fluctuations in the earth’s magnetic field are reported hours or days before an earthquake. Two high school interns spent 16 weeks during 2011-12. They won several honors and awards including: -Regional semifinalists in the 2011- Siemens competition, and - Distinguished Achievement Awards by the Society of Exploration Geophysicists and by theAmerican Association of Physics Teachers and APS at the Intel International Science and Engineering Fair-2012 (Pittsburgh, PA). Fig.2: Magnetic noise at low frequencies for magnetic sensors of trilayers of permendur and LGT, PZT and PMN-PT. The lowest noise is measured for LGT-based sensor which is sensitive enough to measure the fields encountered in magneto-cardiography and field fluctuations in the Earth’s magnetic field that appear hours or days before an earthquake. Appl. Phys. Lett. 100, 052901 (2012)

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