A gradiometer includes a at least one magnet attached to a beam. The magnet moves in response to a magnetic force. A sensing element is configured to measure movement or deflection of the beam or magnet. The gradiometer is configured to determine a gradient of a magnetic field acting on the first magnet based on movement of the magnet. The gradiometer can further measure higher order gradients.

Nano-electromechanical systems (NEMS) devices that utilize thin electrically conductive membranes, which can be, for example, graphene membranes. The membrane-based NEMS devices can be used as sensors, electrical relays, adjustable angle mirror devices, variable impedance devices, and devices performing other functions. The NEMS devices have a serpentine shape arrangement of the electrically conductive membrane. The electrically conductive membrane can be controllably wicked down on the edge of the oxide cavity to increase sensitivity of the NEMS device.

A method is disclosed. In one example, the method includes bonding a first panel of a first material to a base panel in a first gas atmosphere, wherein multiple hermetically sealed first cavities encapsulating gas of the first gas atmosphere are formed between the first panel and the base panel. The method further includes bonding a second panel of a second material to at least one of the base panel and the first panel, wherein multiple second cavities are formed between the second panel and the at least one of the base panel and the first panel.

A method, device, and system for detecting a current leak in a traction power rail. Magnetic or electrical properties of the rail are measured. The measurements are performed using a rail instrument that senses the properties around the rail at various times while the instrument is being moved down the rail, such as using a cart or train. The rail instrument may be a flux concentrator or open Rogowski coil. The locations of the rail, about which the readings are taken by the rail instrument, may be determined and correlated with the measurements themselves. The method may comprise measuring the magnetic field of the rail along a length of the rail, and identifying a leak based on differences between the magnetic field measurements. The system may comprise a cart comprising the rail instrument and a location instrument.

A gradiometer includes a at least one magnet attached to a beam. The magnet moves in response to a magnetic force. A sensing element is configured to measure movement or deflection of the beam or magnet. The gradiometer is configured to determine a gradient of a magnetic field acting on the first magnet based on movement of the magnet. The gradiometer can further measure higher order gradients.

A micro-electro-mechanical system (MEMS) magnetometer is provided for measuring magnetic field components along three orthogonal axes. The MEMS magnetometer includes a top cap wafer, a bottom cap wafer and a MEMS wafer having opposed top and bottom sides bonded respectively to the top and bottom cap wafers. The MEMS wafer includes a frame structure and current-carrying first, second and third magnetic field transducers. The top cap, bottom cap and MEMS wafer are electrically conductive and stacked along the third axis. The top cap wafer, bottom cap wafer and frame structure together form one or more cavities enclosing the magnetic field transducers. The MEMS magnetometer further includes first, second and third electrode assemblies, the first and second electrode assemblies being formed in the top and/or bottom cap wafers. Each electrode assembly is configured to sense an output of a respective magnetic field transducer induced by a respective magnetic field component.

Magnetic field detectors include a proof mass suspended by deformable arms similar to a three dimensional accelerometer. The magnetic field detectors further include magnetically sensitive material present on the proof mass and/or deformable arms to cause movement of the proof mass and/or deformable arms when in the presence of a magnetic field. This movement is converted to an electrical signal and that electrical signal is compared to a reference to determine if a magnetic field of interest is present. The magnetic field detector may be included within an implantable medical device, and when the magnetic field detector indicates that a magnetic field of an MRI scanner is present, the implantable medical device may switch to an MRI mode of operation. The device may also switch back to a normal mode of operation once the MRI scanner is no longer detected such as after a predefined amount of time.

Systems and methods for filtering a micro-electromechanical system sensor rate signal with error feedback are provided. In one example, a micro-electromechanical system sensor rate signal is provided. Next, a feedback signal from a feedback loop is subtracted from the micro-electromechanical system sensor rate signal to produce a first combined signal. The first combined signal is then filtered to produce a filtered rate output. The micro-electromechanical system sensor rate signal is then subtracted from the filtered rate output to produce an error signal, wherein the error signal is used in the feedback loop to generate a feedback signal for a future time step.

The disclosure provides a magnetic field sensor for sensing the magnetic field caused by a current to be measured, which includes: substrate; a first drive electrode with a path for flowing a reference current supplied from the substrate arranged so as to be moveable by the magnetic field of the current to be measured; and a second drive electrode with a path for flowing a reference current supplied from the substrate arranged so as to be moveable by the magnetic field of the current to be measured, thus measuring the variation of a capacitance caused by the movement of the first drive electrode and the second drive electrode. Hence, the sensing is achieved by the two drive electrodes with no reference electrode, thus maximizing the mechanical displacement to improve the sensing capability.

A magnetic field gradient sensor includes a support and a structure having at least a first and a second mobile element, at least one magnetic sensor, each magnetic sensor being mechanically secured to one of the first and/or second mobile elements so as to be able to apply a mechanical force to the structure in the presence of a magnetic field gradient, a coupler for coupling between the first and second mobile elements so that the structure can be moved in at least one balanced mechanical mode in the presence of a magnetic field gradient, and a sensor for measuring the movement of the structure at least in balanced mode.