Magnetoelectric magnetic field sensor with longitudinally biased magnetostrictive layer
First Claim
1. A magnetoelectric magnetic field sensor, comprising:
- a) a magnetostrictive layer having a longitudinal bias magnetic field, wherein the magnetostrictive layer has a L/T aspect ratio greater than 1;
b) a piezoelectric layer bonded to the magnetostrictive layer; and
c) a means for creating the longitudinal bias magnetic field in the magnetostrictive layer.
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Abstract
A magnetoelectric magnetic field sensor has one or more laminated magnetostrictive layers and piezoelectric layers. The magnetostrictive layers are magnetized by a bias magnetic field in a longitudinal, in-plane direction. The piezoelectric layers can be poled in the longitudinal direction or perpendicular direction. The longitudinal magnetization of the magnetostrictive layers provides greatly increased sensitivity at lower bias fields compared to other magnetoelectric sensors. Perpendicular poling of the piezoelectric layers tends to provide higher sensitivity at lower detection frequency (e.g. less than 1 Hz). Longitudinal poling tends to provide higher sensitivity at high detection frequency (e.g. above 10 Hz). Also included are embodiments having relative thicknesses for the magnetostrictive layers that are optimized for sensitivity. Equations are provided for calculating the best relative thickness for the magnetostrictive layer for maximum sensitivity.
32 Citations
22 Claims
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1. A magnetoelectric magnetic field sensor, comprising:
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a) a magnetostrictive layer having a longitudinal bias magnetic field, wherein the magnetostrictive layer has a L/T aspect ratio greater than 1; b) a piezoelectric layer bonded to the magnetostrictive layer; and c) a means for creating the longitudinal bias magnetic field in the magnetostrictive layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 20)
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15. A magnetoelectric magnetic field sensor, comprising:
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a) one or more magnetostrictive layers having a longitudinal magnetization; b) one or more piezoelectric layers bonded to the magnetostrictive layer, and wherein a thickness ratio of adjacent magnetostrictive and piezoelectric layers is within 50% of a value given by the equation - View Dependent Claims (16, 17, 18, 21)
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19. A magnetoelectric magnetic field sensor, comprising:
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a) a magnetostrictive layer having a longitudinal bias magnetic field, wherein the magnetostrictive layer has a L/T aspect ratio greater than 1.5; b) a piezoelectric layer bonded to the magnetostrictive layer; and c) a permanent magnet for creating the longitudinal bias magnetic field in the magnetostrictive layer. - View Dependent Claims (22)
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Specification