Electric generators and magnetic-field sensors of a proposed type would be based on the magnetoelectric effect. A simple device of this type (see figure) would consist mainly of an inner layer of a magnetoelectric material sandwiched between two outer layers of a ferromagnetic material. Electrical contacts would be placed at opposite ends of the magnetoelectric material.
As its name suggests, a magnetoelectric material is one that exhibits the magnetoelectric effect, which is a linear coupling between magnetization and electric polarization. The polarization electric field is perpendicular to the magnetic induction vector and its magnitude is proportional to the strength of the magnetic induction vector.
The electrical contacts could be used to connect the ends of the magnetoelectric layer to a voltmeter or other suitable instrument for measuring changes in the polarization electric charge. The voltage reading would be proportional to the change in the charge and thus to the change in the polarization electric field and thus, further, to change in the magnetic induction. Operated in this way, the device could be used as a magnetic-field sensor.
If the ends of the magnetoelectric layer were connected to suitable external circuitry and the magnetic field varied, then a sustained electrical current would flow. Operated in this way, the device could be used to sense or to extract power from a strongly varying magnetic field.
This work was done by Julian Blosiu and Mary Boghosian of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Electronics & Computers category. NPO-20523
This Brief includes a Technical Support Package (TSP).
Magnetoelectric Sensors and Electric Generators
(reference NPO-20523) is currently available for download from the TSP library.
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