216results about "Magnetic field measurement using permanent magnets" patented technology

The present invention provides an MFM or MRFM analytical device comprising a micro-dimensional probe that is capable of detecting single proton and single electron spin. Furthermore, it provides an MFM or MRFM device comprising a micro-dimensional probe, that is capable of detecting magnetic structures of size of order one nanometer. In particular, the present invention provides a micro-dimensional probe for an MFM or MRFM device that comprises a CNT cantilever that comprises a nanoscale ferromagnetic material. The CNT cantilever can be attached to an electrode as a component of a microscopic probe which is coupled with an electrical circuit as a component of a device for nanoscale MFM or MRFM micro-dimensional probes. The device comprising the probe and electrical circuit can be incorporated into an existing scanning probe microscope (SPM) apparatus having accommodation for electrical readout.

A magnetic-field-detecting and / or generating apparatus comprises a non-ferromagnetic tip with a longitudinal member of ferromagnetic material embedded in the tip. Further, magnetic-shield means is arranged around the tip. At the end of the longitudinal member a magnetic-field device is arranged. The same principle can be applied to read / write heads for use in magnetic-storage devices.

A magnetic field sensor including a body including a magnetic mechanism capable of forming a torque applied on the body by action of an external magnetic field to be detected; a connector, separated from the body, mechanically connecting the body to an inlay portion of the sensor by at least one pivot link having an axis perpendicular to the direction of the magnetic field to be detected; a detector detecting stress applied by the body by action of the torque, separated from the connector and including at least one suspended stress gauge including a first part mechanically connected to the inlay portion, a second part mechanically connected to the body, and a third part provided between the first and second parts and suspended between the inlay portion and the body.

There is disclosed a scanning probe microscope for producing a topographic image of a surface of a sample by noncontact AFM (atomic force microscopy). First, a first topographic image of the sample undergoing magnetic effects is produced from the resonance frequency of a cantilever by FM detection. Then, a second topographic image of the sample free of magnetic effects is produced from the amplitude of the cantilever by slope detection. The difference between these two topographic images is taken. Thus, a magnetic force image is produced.

A micromachined magnetic field sensor comprising is disclosed. The micromachined magnetic field comprises a substrate; a drive subsystem, the drive subsystem comprises a plurality of beams, and at least one anchor connected to the substrate; a mechanism for providing an electrical current through the drive subsystem along a first axis; and Lorentz force acting on the drive subsystem along a second axis in response to a magnetic field along a third axis. The micromachined magnetic field sensor also includes a sense subsystem, the sense subsystem comprises a plurality of beams, and at least one anchor connected to the substrate; wherein a portion of the sense subsystem moves along a fourth axis; a coupling spring between the drive subsystem and the sense subsystem which causes motion of the sense subsystem in response to the magnetic field; and a position transducer to detect the motion of the sense subsystem.

A linear motion sensor has two pairs of opposed spaced apart stacks of two simple two-pole bar magnets. Each stack has one shorter outer magnet and one longer inner magnet, with the outer magnets centered on the inner magnets. The poles of the magnets are oriented the same in each pair, but opposite with respect to the other pair. The shape of the magnets results in the magnetic fields produced by each pair of magnets being substantially outside of the magnets themselves, so that the load line for the combined magnets is above the knee in its B / H material demagnetization curve. The pairs of magnets define a gap therebetween in which a magnetic field sensor is mounted for travel. The shorter magnets are about one half the length of the longer magnets such that the magnetic field in the gap varies substantially linearly as the sensor moves along the gap.

A micromachined magnetic field sensor is disclosed. The micromachined magnetic field sensor comprises a substrate; and a drive subsystem partially supported by the substrate with a plurality of beams, and at least one anchor; a mechanism for providing an electrical current through the drive subsystem along a first axis; and Lorentz force acting on the drive subsystem along a second axis in response to a magnetic field vector along a third axis. The micromachined magnetic field sensor also includes a position transducer to detect the motion of the drive subsystem and an electrostatic offset cancellation mechanism coupled to the drive subsystem.

Disclosed herein are a magnetic field sensor and a sensing apparatus using the same. The present invention provides a magnetic field sensor including: a magnetic field detection unit which includes a substrate, a piezoelectric driving body formed on the substrate, and a magnetostrictive layer stacked on one portion of the piezoelectric driving body and is vibrated at a vibration frequency changed from a natural frequency in proportion to a magnitude of an external magnetic field; and a control unit which drives the piezoelectric driving body with a constant AC voltage and calculates a magnitude of the external magnetic field from an output voltage output from the magnetic field detection unit, and a sensing apparatus using the same.

A system for measuring a physical characteristic of a bearing includes a permanent magnet and a magnetic sensor. The permanent magnetic is coupled to at least a portion of a bearing, and has a magnetic field that changes as a function of the physical characteristic. For example, the permanent magnet has a magnetic characteristic that changes as a function of temperature. The magnetic sensor is operably disposed in a magnetic field sensing relationship with the permanent magnet, and is configured to generate a voltage signal and / or current signal corresponding to a sensed magnetic field.

A current sensor includes a pair of magnetic balance sensors and a switching circuit. The magnetic balance sensors each include a magnetic sensor element and a feedback coil. The magnetic sensor element varies in characteristics due to an induction field caused by measurement current. The feedback coil is disposed near the magnetic sensor element and produces a canceling magnetic field canceling out the induction field. Each of the magnetic balance sensors outputs, as a sensor output, a value corresponding to current flowing through the feedback coil when a balanced state in which the induction field and the canceling magnetic field cancel each other out is reached after the feedback coil is energized. The switching circuit turns on / off one of the magnetic balance sensors.

Two suspended masses are configured so as to be flowed by respective currents flowing in the magnetometer plane in mutually transversal directions and are capacitively coupled to lower electrodes. Mobile sensing electrodes are carried by the first suspended mass and are capacitively coupled to respective fixed sensing electrodes. The first suspended mass is configured so as to be mobile in a direction transversal to the plane in presence of a magnetic field having a component in a first horizontal direction. The second suspended mass is configured so as to be mobile in a direction transversal to the plane in presence of a magnetic field having a component in a second horizontal direction, and the first suspended mass is configured so as to be mobile in a direction parallel to the plane and transversal to the current flowing in the first suspended mass in presence of a magnetic field having a component in a vertical direction.

A scanning probe detects phase changes of a cantilevered tip proximate to a sample, the oscillations of the cantilevered tip are induced by a lateral bias applied to the sample to quantify the local impedance of the interface normal to the surface of the sample. An ac voltage having a frequency is applied to the sample. The sample is placed at a fixed distance from the cantilevered tip and a phase angle of the cantilevered tip is measured. The position of the cantilevered tip is changed relative to the sample and another phase angle is measured. A phase shift of the deflection of the cantilevered tip is determined based on the phase angles. The impedance of the grain boundary, specifically interface capacitance and resistance, is calculated based on the phase shift and the frequency of the ac voltage. Magnetic properties are measured by applying a dc bias to the tip that cancels electrostatic forces, thereby providing direct measurement of magnetic forces.

A scanning microscope for high resolution current imaging by direct magnetic field sensing of a sample maintained in an ambient environment. The scanning microscope uses a magnetic sensor such as a SQUID and a fiber probe magnetically coupled between the SQUID sensor and the sample under study. The fiber probe has a sharply defined tip for high resolution probing and for reaching minute cavities on the surface of the sample. The coupling between the tip of the fiber probe and the sample is controlled by a distance control mechanism, in the range of 1-100 nm. The material of the fiber probe with high permeability and low magnetic noise is chosen to optimize flux transmission to the magnetic sensor. Magnetic coupling to the sensor is maximized by keeping the distance between the end of the fiber probe and the sensor to approximately 0-100 μm. The fiber probe is integrated into the fiber holder for easy replacement of the fiber probe.

A magnetic-field sensor, including: a die, a current generator in the die. The current generator generating a driving current. A Lorentz force transducer also in the die and being configured to obtain measurements of magnetic field based upon the Lorentz force is coupled to the current generator. The transducer having a resonance frequency. The current generator is such that the driving current has a non-zero frequency different from the resonance frequency.

A system for measuring a physical characteristic of mechanical face seal includes a permanent magnet and a magnetic sensor. The permanent magnet is affixed to a structure proximate to a bearing surface of the mechanical face seal. The permanent magnet has a magnetic field that decreases as a function of temperature. The magnetic sensor is mounted on the mechanical face seal in a magnetic field sensing relationship with the permanent magnet. The magnetic sensor is configured to generate a voltage signal corresponding to a sensed magnetic field.

Sensors for outputting signals indicative of a magnetic drag force between a ferromagnetic sample that is or has been in motion relative to one or more measurement magnets are described. Such sensors include at least one measurement magnet and a sensing element operably associated therewith, such that upon or after exposure of the measurement magnet(s) to a ferromagnetic sample in motion relative thereto, the sensor can sense the drag force, if any, or changes therein, experienced by the measurement magnet. Devices for detecting and / or measuring magnetic drag force that employ one or more of these sensors are also described, as are various applications for such devices.

A passive alternating current sensor for sensing a current-carrying conductor is disclosed. The passive alternating current sensor includes a substrate, a magnetic body, at least one coil and a first measuring circuit. The substrate has a flexible structure layer. The magnetic body is disposed correspondingly to the current-carrying conductor and located at one side of the substrate. The coil is disposed on the substrate and correspondingly winds around the magnetic body. The first measuring circuit is connected with the coil. When the magnetic body is subjected to the magnetic field generated by the current-carrying conductor and enabled a relative motion with the coil, the coil produces an induced electromotive force. The first measuring circuit measures the induced electromotive force and accordingly outputs a first induction signal.

Provided is a small-sized metal detection sensor capable of detecting a minute foreign metal substance by an electromagnetic induction detection method. The metal detection sensor 20 for detecting a metal 14 included in an inspection object moving on a path 18, includes: magnets 24, 26 which generate static magnetic fields; and a coil 30 which detects a magnetic field 28 generated by the metal 14.The magnets 24, 26 are positioned outside the coil 30 relative to the axial direction of the coil 30. The coil 30 is positioned outside the magnets 24, 26 relative to the axial direction connecting the N pole and the S pole of each of the magnets 24, 26. The magnets 24, 26 are opposed to the coil 30.

The present invention provides an amplitude modulator, which is disposed in an area through which a magnetic field flows so as to modulate amplitudes, comprising: a substrate; a first driving electrode which receives a first frequency signal and a second frequency signal supplied from the substrate and carries out resonant motion by the magnetic field; and a second driving electrode for receiving the second frequency signal and carries out resonant motion by the first driving electrode and the magnetic field, wherein a modulated signal is generated by modulating the amplitudes of the first and second frequency signals through the resonant motions of the first and second driving electrodes. Therefore, since the signal generated by modulating a carrier signal through mechanical resonance according to the magnetic field is outputted, amplitude modulation can be carried out without a complicated circuit configuration. In addition, since an MEMS device is a single structure that does not include an insulating layer, a single signal is applied to one structure, thereby simplifying driving, and all the driving electrodes of both ends thereof are driven so as to double a change in variable capacitance, thereby improving sensing ability.

An apparatus comprising a substrate and a MEM device. The MEM includes a comb capacitor and a magnetic element physically connected to one electrode of the comb capacitor. The magnetic element is capable of moving the one electrode in a manner that alters a capacitance of the comb capacitor. The apparatus also includes at least one spring physically connecting the magnetic element to the substrate.

A device and method for mapping magnetic fields of a sample at a resolution less than the wavelength of light without altering the magnetic field of the sample is disclosed. A device having a tapered end portion with a magneto-optically active particle positioned at the distal end thereof in communication with a fiber optic for transferring incoming linearly polarized light from a source thereof to the particle and for transferring reflected light from the particle is provided. The fiber optic has a reflective material trapping light within the fiber optic and in communication with a light detector for determining the polarization of light reflected from the particle as a function of the strength and direction of the magnetic field of the sample. Linearly polarized light from the source thereof transferred to the particle positioned proximate the sample is affected by the magnetic field of the sample sensed by the particle such that the difference in polarization of light entering and leaving the particle is due to the magnetic field of the sample. Relative movement between the particle and sample enables mapping.

In a method for scanning microscopy, for which the surface of a sample is scanned point-by-point using a tunnel tip and locally resolved tunnel current measurement is performed, during scanning the tunnel tip is remagnetized by a predetermined remagnetization frequency, and from the tunnel current (It) or a z coordinate of the distance between the tunnel tip and the sample or a value derived from this, locally resolved signal components are derived, occurring at the remagnetization frequency and being characteristic for magnetic sample properties, whereby on the basis of the derived signal components an imaging of the magnetic structure of the sample surface is performed.