Rotatable micromachined device for sensing magnetic fields
First Claim
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1. A micromachined electromechanical device comprising:
- a structure suspended above a substrate, rotatable about a first axis, and having at least one rotatable structure finger;
at least one flexible suspension arm, each suspension arm having a first end connected to the substrate and a second end connected to the rotatable structure;
at least one first fixed finger connected to the substrate, each first fixed finger being adjacent to a first side of one of the rotatable structure fingers;
at least one second fixed finger connected to the substrate, each second fixed finger being adjacent to a second side of one of the rotatable structure fingers; and
a ferromagnetic material having a magnetic moment along a second axis, perpendicular to the first axis, and connected to the rotatable structure, so that the rotatable structure is rotatable in response to a magnetic field having a component perpendicular to the first axis and perpendicular to the second axis.
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Abstract
A micromachined magnetometer is built from a rotatable micromachined structure on which is deposited a ferromagnetic material magnetized along an axis parallel to the substrate. A structure rotatable about the Z-axis can be used to detect external magnetic fields along the X-axis or the Y-axis, depending on the orientation of the magnetic moment of the ferromagnetic material. A structure rotatable about the X-axis or the Y-axis can be used to detect external magnetic fields along the Z-axis. By combining two or three of these structures, a dual-axis or three-axis magnetometer is obtained.
56 Citations
21 Claims
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1. A micromachined electromechanical device comprising:
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a structure suspended above a substrate, rotatable about a first axis, and having at least one rotatable structure finger; at least one flexible suspension arm, each suspension arm having a first end connected to the substrate and a second end connected to the rotatable structure; at least one first fixed finger connected to the substrate, each first fixed finger being adjacent to a first side of one of the rotatable structure fingers; at least one second fixed finger connected to the substrate, each second fixed finger being adjacent to a second side of one of the rotatable structure fingers; and a ferromagnetic material having a magnetic moment along a second axis, perpendicular to the first axis, and connected to the rotatable structure, so that the rotatable structure is rotatable in response to a magnetic field having a component perpendicular to the first axis and perpendicular to the second axis. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A micromachined electromechanical device comprising:
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a plurality of magnetometers, each magnetometer having a first structure rotatable about an axis, the structure being suspended above a substrate and having a rotatable electrode; at least one flexible suspension arm, each suspension arm having a first end connected to the substrate and a second end connected to the rotatable structure; a first fixed plate connected to the substrate and having a first electrode, the first electrode and the rotatable electrode forming a first capacitor, wherein rotation of the structure in a first direction about the axis increases the capacitance of the first capacitor and rotation of the structure in a second direction about the axis decreases the capacitance of the first capacitor; a second fixed plate connected to the substrate and having a second electrode, the second electrode and the rotatable electrode forming a second electrode, the second electrode and the rotatable electrode forming a second capacitor, wherein rotation of the structure in the first direction decreases the capacitance of the second capacitor and rotation of the structure in the second direction increases the capacitance of the second capacitor; and a ferromagnetic material having a magnetic moment oriented perpendicularly to the axis and connected to the rotatable structure, so that the rotatable structure is rotatable in response to a magnetic field having a component perpendicular to the axis and perpendicular to the orientation of the magnetic moment. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A micromachined electro-mechanical device comprising:
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a structure rotatable about a first axis perpendicular to a top surface of a substrate, the structure being suspended above the substrate and having at least one rotatable finger; a plurality of flexible suspension arms suspended above the substrate, each suspension arm having a first end connected to the rotatable structure and a second end extending outward from the first end and connected to the substrate; at least one first fixed finger suspended above the substrate, each first finger being adjacent to a first side of one of the rotatable fingers and connected to the substrate; at least one second finger suspended above the substrate, each second finger being adjacent to a second side of one of the rotatable fingers and connected to the substrate; and a ferromagnetic material having a magnetic moment along a second axis, parallel to the top surface of the substrate, and connected to the rotatable structure, so that the rotatable structure is rotatable in response to a magnetic field having a component parallel to the top surface of the substrate and perpendicular to the second axis. - View Dependent Claims (15, 16, 17, 18)
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19. A micromachined electromechanical device comprising:
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a structure rotatable about a first axis parallel to a top surface of a substrate, the structure being suspended above the substrate and having a rotatable electrode; a plurality of flexible suspension arms suspended above the substrate, each suspension arm having a first end connected to the rotatable structure and a second end extending outward from the first end and connected to the substrate; a first fixed plate connected to the substrate, the first plate having a first electrode, the first electrode and the rotatable electrode forming a first capacitor wherein rotation of the rotatable structure in a first direction about the first axis increases the capacitance of the first capacitor and rotation of the rotatable structure in a second direction about the first axis decreases the capacitance of the first capacitor; a second fixed plate connected to the substrate, the second plate having a second electrode, the second electrode and the rotatable electrode forming a second capacitor wherein rotation of the rotatable structure in the first direction decreases the capacitance of the second capacitor and rotation of the rotatable structure in the second direction increases the capacitance of the second capacitor; and a ferromagnetic material having a magnetic moment along a second axis, parallel to the top surface of the substrate and perpendicular to the first axis, and connected to the rotatable structure, so that the rotatable structure is rotatable in response to a magnetic field having a component perpendicular to the top surface of the substrate. - View Dependent Claims (20, 21)
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Specification