Abstract: An accelerometer includes a housing, a magnetic fluid within the housing, and an inertial body suspended in the magnetic fluid and generally constrained to move along a single axis. Centering magnets are positioned on two sides of the inertial body along the axis. A detector provides a signal indicative of acceleration based on displacement of the inertial body. A plurality of stops can be placed on the inertial body inside the housing. A coil winding can be placed on the housing to be coupled to the inertial body for maintaining the inertial body substantially in place. Cavities with air can be on sides of the inertial body. Openings in the housing can be placed at locations of the cavities. The inertial body can have a channel connecting the cavities. The detector can be a Hall sensor, a digital Hall sensor, or two Hall sensors for differential detection of the acceleration. The housing can have two lids that substantially enclose, within the housing, magnetic fields from the centering magnets.

Abstract: A sensor includes a housing and a magnetic fluid within the housing that incompletely fills the housing. An inertial body is in contact with the magnetic fluid. Displacement of the inertial body relative to the magnetic fluid is indicative of acceleration on the housing. The acceleration includes linear and/or angular acceleration. The inertial body can be an air bubble, or a dissimilar liquid. A plurality of magnets are mounted on the housing, wherein the magnetic fluid is positioned in droplets between the magnets and the inertial body. The magnetic fluid can be a single droplet between each magnet and the inertial body, or multiple droplets between each magnet and the inertial body. The remaining volume in the housing can be filled with a non-magnetic fluid.

Abstract: An accelerometer includes an inertial body; a magnetized fluid holding the inertial body in suspension; and a plurality of capacitive elements, each forming a capacitor with the inertial body. A displacement of the inertial body produces a change of capacitance of the capacitive elements that is indicative of acceleration. The capacitive elements include at least two capacitive elements per side of the accelerometer. A housing encloses the inertial body and the magnetized fluid, and the plurality of capacitive elements are mounted on the housing. The housing can be cylindrical shaped, rectangular shaped and tetrahedral-shaped. The inertial body can include a disk-shaped magnet, an annular-shaped magnet, or be non-magnetic, or be weakly magnetic. The acceleration can be linear acceleration, angular acceleration, or three components of angular acceleration and three components of linear acceleration. A plurality of magnets magnetize the magnetic fluid.

Abstract: A sensor includes an inertial body; a plurality of sources of magnetic field located generally surrounding the inertial body; magnetic fluid between the sources and the inertial body; and a non-magnetic coating on surfaces of the sources facing the magnetic fluid. Displacement of the inertial body is indicative of acceleration. The acceleration can include linear acceleration and angular acceleration. The angular acceleration can include three components of acceleration about three orthogonal axes. The sources include permanent magnets, or electromagnets, or both. A plurality of sensing coils detect changes in magnetic field within the magnetic fluid due to the displacement of the inertial body. The non-magnetic coating can also cover the sensing coils. A housing encloses the inertial body and the magnetic fluid. The magnetic fluid can use kerosene, water or oil as the carrier liquid. The magnetic fluid is a colloidal suspension.

Abstract: A sensor includes a housing and a magnetic fluid within the housing that incompletely fills the housing. An inertial body is in contact with the magnetic fluid. Displacement of the inertial body relative to the magnetic fluid is indicative of acceleration on the housing. The acceleration includes linear and/or angular acceleration. The inertial body can be an air bubble, or a dissimilar liquid. A plurality of magnets are mounted on the housing, wherein the magnetic fluid is positioned in droplets between the magnets and the inertial body. The magnetic fluid can be a single droplet between each magnet and the inertial body, or multiple droplets between each magnet and the inertial body. The remaining volume in the housing can be filled with a non-magnetic fluid.