Sensormatic Electronics Corporation

Massachusetts Institute of Technology

Spinix Corporation

Ferro Solutions, Inc.

Other

Robert C O'Handley

Wing Kei Ho

Yi-Qun Li

Ming-Ren Lian

Nen-Chin Liu

Gerald Francis Dionne

David Bono

Chun Zhang

Jiankang Huang

Richard Loyd Copeland

Nicholas J Grant

David N Lambeth

Kevin Robert Coffey

Alan P Sliski

Enrique J Lavernia

Kari M Ullakko

Dennis Michael Gadonniex

Benjamin L Averbach

Yutaka Hara

Yi-Wun Li

Hariharan Venketesh Sundram

Toshiro Kuji

Laura J Henderson

Teiichi Ando

Tetsuji Harada

Nen-chin Liu

Apparatus and method for harvesting energy from the environment and/or other external sources and converting it to useful electrical energy. The harvester does not contain a permanent magnet or other local field source but instead relies on the earth's magnetic field of another source of a magnetic field that is external to the sensing device. One advantage of these new harvesters is that they can be made smaller and lighter than energy harvesters that contain a magnet and/or an inertial mass.

Apparatus and method utilizing magnetic field

Energy harvester utilizing external magnetic field

An inductive energy harvester comprises a permanent magnet magnetic field source attached by a pair of compact spiral disk springs to an induction coil. The springs position the magnet so that the induction coil surrounds one end of the magnet where the flux density is greatest. In addition, the magnetic flux emerging from that end of the magnet is enhanced by a disk of magnetic material having high permeability and high flux density. In another embodiment, the magnetic field source comprises two dipole magnets arranged in opposing flux relationship with a thin layer of high flux density, high magnetic permeability material located in a gap between the magnets.

High efficiency, inductive vibration energy harvester

In a vibrational energy harvester, an external vibration causes relative motion between a permanent magnet and a magnetic field sensing element composed of a magnetostrictive material bonded to an electroactive material. The changing magnetic field causes a rotation of magnetization in the magnetostrictive material and the rotating magnetization generates a stress in the magnetostrictive material. The stress is transmitted to the electroactive material, which responds by generating electrical power.

High efficiency vibration energy harvester

Passive solid-state magnetic sensors comprise a magnetostrictive material in contact with a piezoelectric material. The magnetostrictive material strains under the influence of an external magnetic field and imparts stress to the piezoelectric material to produce a detectable voltage signal indicative of the external field. Sensors have applications in rotor speed detection, electrical current measurements, magnetic imaging, magnetic field detection, read heads, and MRAM, for example.

Passive magnetic field sensors having magnetostrictive and piezoelectric materials

Passive solid-state magnetic sensors are based on the combination of magnetorestrictive materials and piezoelectric materials. Sensors have applications in rotor speed detection, magnetic field detection, read heads, and MRAM, for example.

Passive solid-state magnetic field sensors and applications therefor

Passive solid-state magnetic sensors are based on the combination of magnetorestrictive materials and piezoelectric materials. Sensors have applications in motor speed detection, magnetic field detection, read heads, and MRAM, for example.

Method and system for estimating a concentration of free electrons with a selected spin polarization in a semiconductor material. A static magnetic field and an electromagnetic field are impressed on the semiconductor, and free electrons are injected (through diffusion or tunneling) into the semiconductor material from a ferromagnetic material. Motion of the injected, spin-polarized electrons, within the semiconductor gives rise to a Hall voltage across the semiconductor. This voltage is measured at one or more spaced apart locations and analyzed to detect presence of, and estimate a concentration of, free electrons with a selected spin at at least one location within the semiconductor. Effects of an imposed stress, temperature, illumination or electromagnetic field on the semiconductor can be determined.

Detection of polarized spin transport in semiconductors

A magnetostrictive element for use in a magneto-mechanical marker has a resonant frequency characteristic that is at a minimum at a bias field level corresponding to the operating point of the magnetomechanical marker. The magnetostrictive element has a magnetomechanical coupling factor k in the range 0.28 to 0.4 at the operating point. The magnetostrictive element is formed by applying cross-field annealing to an iron-rich amorphous metal alloy ribbon (45 to 82 percent iron) which includes a total of from 2 to 17 percent of one or more of Mn, Mo, Nb, Cr, Hf, Zr, Ta, V. Cobalt, nickel, boron, silicon and/or carbon may also be included. The metal alloy may include one early transition element selected from the group consisting of Zr, Hf and Ta, and also a second early transition element selected from the group consisting of Mn, Mo, Nb, Cr, and V.

Iron-rich magnetostrictive element having optimized bias-field-dependent

A magnetomechanical EAS marker is formed of a housing, a magnetostrictive active element in the housing and a bias element fixedly mounted on the housing. A central portion of the active element is secured to the housing to keep the active element from shifting in a longitudinal direction relative to the bias element and to keep ends of the active element spaced from the housing. The active element remains free to mechanically resonate in response to an EAS interrogation signal. The stable positioning of the active element prevents variations in the bias magnetic field due to shifting relative to the bias element, while keeping ends of the active element free from frictional damping due to mechanical loading from contact with the housing.

Stabilizing the position of an active element in a magnetomechanical EAS

Magnetically-controlled actuator materials are provided that produce large actuation stroke, that exhibit fast actuation response time and corresponding high-frequency operation, and that enable efficient actuation energy conversion at convenient operating temperatures. The actuator materials exhibit an austenitic crystal structure above a characteristic phase transformation temperature and exhibit a martensitic twinned crystal structure below the phase transformation temperature. One actuator material provided by the invention is an alloy composition that can be defined generally as (Ni.sub.a Fe.sub.b Co.sub.c).sub.65-x-y (Mn.sub.d Fe.sub.e Co.sub.f).sub.20+x (Ga.sub.g Si.sub.h Al.sub.i).sub.15+y, where x is between about 3 atomic % and about 15 atomic % and y is between about 3 atomic % and about 12 atomic %, and where a+b+c=1, where d+e+f=1, and g+h+i=1. The actuator material is characterized by a magnetocrystalline anisotropy energy that is sufficient for enabling motion of twin boundaries of the martensitic twinned crystal structure in response to application of a magnetic field to the martensitic twinned crystal structure. This enables the material to produce an actuation stroke in response to the magnetic field. Based on this actuation mechanism, the actuator materials of the invention overcome the thermal, stroke, and frequency response limitations typically associated with actuator materials, and enable a class of actuators with large stroke and high speed at convenient temperatures.

High-strain, magnetic field-controlled actuator materials

A magnetostrictive element for use in a magnetomechanical marker has a resonant frequency characteristic that is at a minimum at a bias field level corresponding to the operating point of the magnetomechanical marker. The magnetostrictive element has a magnetomechanical coupling factor k in the range 0.28 to 0.4 at the operating point. The magnetostrictive element is formed by applying current-annealing to an iron-nickel-cobalt based amorphous metal ribbon, or by cross-field annealing an iron-nickel-cobalt alloy that includes a few percent chromium and/or niobium.

Magnetostrictive element having optimized bias-field-dependent resonant

A self-biasing magnetostrictive element for use in a magnetomechanical EAS marker is a strip of amorphous alloy with crystalline particles of semi-hard or hard magnetic material distributed throughout the bulk of the amorphous alloy strip. The crystalline particles are magnetized to bias the amorphous alloy strip to resonate in response to an interrogation signal. The crystalline particles are formed by heat-treating the amorphous alloy strip at a temperature above the Curie temperature of the amorphous alloy in the presence of a longitudinal magnetic field. The alloy strip is then cross-field annealed at a temperature below the Curie temperature of the amorphous alloy to form a transverse anisotropy in the amorphous bulk of the alloy strip. A preferred alloy composition includes iron, cobalt, niobium, copper, boron and silicon.

Active element for magnetomechanical EAS marker incorporating particles

A self-biasing magnetostrictive element for a magnetomechanical EAS marker is formed by first annealing a ribbon of ferromagnetic material in the presence of a magnetic field applied in a transverse direction relative to the ribbon's longitudinal axis, and then annealing the ribbon a second time in the presence of a magnetic field applied in the direction of the longitudinal axis. The twice-annealed ribbon exhibits remanent magnetization along the longitudinal axis and has plural magnetic domains situated along the longitudinal axis. The orientation of magnetization in each domain is canted by .+-..theta..degree.&lt;90.degree. from the ribbon axis with the direction of canting alternating from domain to domain.

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Andover, MA, United States of America

Robert C O'Handley