Micromachined cantilever structure providing for independent multidimensional force sensing using high aspect ratio beams
First Claim
1. A micromachined cantilever structure for deflection sensing comprising:
- a) a base;
b) a beam portion having a fixed end and a free end, said fixed end being attached to said base, said beam portion comprising at least one X-deflecting high aspect ratio rib extending in a Y-direction and oriented planar parallel to a ZY plane such that the rib may laterally deflect in a X-direction;
c) a first lateral-sensing piezoresistor positioned in a side of said at least one high aspect ratio rib such that the resistance of said first lateral-sensing piezoresistor changes when said free end is deflected laterally; and
d) a first electrical circuit in said cantilever structure for sensing the change in resistance of said first lateral-sensing piezoresistor.
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Accused Products
Abstract
A micromachined structure providing for independent vertical and lateral deflection sensing. The structure uses high aspect ratio ribs which bend much more easily in one direction than in other directions (i.e., have a predominant direction of compliance). One or more ribs are combined to form beams which also have one predominant direction of compliance. Two such beams are bonded end to end, and one end of the beam pair is bonded to a base. The beams are oriented orthogonally to one another such that they independently bend to vertical and lateral external forces. Further, three dimensional force sensing can be accomplished by adding a third beam. Sensors can independently sense the bending in each beam and thereby independently measure the dimensional components of bending forces applied to the free end of the structure. In the preferred embodiment, piezoresistive sensors are formed on the ribs comprising the beams. The piezoresistors can be made by ion-implantation, for example. Measurement of the change in resistance of the sensors is then a measure of the beam deflection and the external force. The resistances of the sensors can be measured independently. Other sensing means include voltage measurement of piezoelectric effects, optical deflection and interference sensing techniques, and capacitive deflection sensors.
87 Citations
35 Claims
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1. A micromachined cantilever structure for deflection sensing comprising:
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a) a base; b) a beam portion having a fixed end and a free end, said fixed end being attached to said base, said beam portion comprising at least one X-deflecting high aspect ratio rib extending in a Y-direction and oriented planar parallel to a ZY plane such that the rib may laterally deflect in a X-direction; c) a first lateral-sensing piezoresistor positioned in a side of said at least one high aspect ratio rib such that the resistance of said first lateral-sensing piezoresistor changes when said free end is deflected laterally; and d) a first electrical circuit in said cantilever structure for sensing the change in resistance of said first lateral-sensing piezoresistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19)
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18. A micromachined cantilever structure for three dimensional deflection sensing comprising:
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a) a base; b) at least one X-deflecting high aspect ratio rib having a fixed end and a free end, the fixed end being attached to the base such that the rib extends in a Y-direction from the base, wherein the rib is disposed planar parallel with a ZY plane such that the rib may deflect in a X-direction, and wherein the rib has an aspect ratio of at least 2;
1;c) a probe base attached to the free end of the rib; d) a Y-deflecting high aspect ratio rib attached to the probe base, wherein the Y-deflecting rib is disposed planar parallel with a XZ plane such that the Y-deflecting rib may deflect in a Y-direction, and wherein the Y-deflecting rib has an aspect ratio of at least 2;
1;d) a high aspect ratio probe attached to the Y-deflecting rib, the probe having a probe tip, wherein the probe is disposed planar parallel with a XY-plane such that the probe may deflect in a Z-direction; whereby the X-deflecting rib deflects in the X-direction in response to a force applied in the X-direction to the probe tip, the Y-deflecting rib deflects in the Y-direction in response to a force applied in the Y-direction to the probe tip, and the probe deflects in the Z-direction in response to a force applied in the Z-direction to the probe tip. - View Dependent Claims (32, 33, 34, 35)
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20. A micromachined cantilever structure for multidirectional deflection sensing comprising:
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a) a base; b) a first high aspect ratio rib oriented planar parallel to a first plane such that it most easily bends in a first direction; c) a second high aspect ratio rib oriented planar parallel to a second plane such that it most easily bends in a second direction, and d) a sensing means for independently sensing bending in said first rib and bending in said second rib; wherein; 1) said first direction and said second direction are perpendicular; 2) one end of said first rib is bonded to said base; 3) one end of said second rib is bonded to said first rib opposite said base such that said second rib has a free end opposite said first rib; and 4) said first plane and said second plane are perpendicular; whereby said first rib and said second rib may bend in perpendicular directions in response to a force applied to said free end. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A micromachined cantilever structure for deflection sensing comprising:
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a) a base; b) at least one X-deflecting high aspect ratio rib having a fixed end and a free end, the fixed end being attached to the base such that the rib extends in a Y-direction from the base, wherein the rib is disposed planar parallel with a ZY plane such that the rib may deflect in a X-direction, and wherein the rib has an aspect ratio of at least 2;
1;c) a probe base attached to the free end of the rib; d) a high aspect ratio probe attached to the probe base, the probe having a probe tip, wherein the probe is disposed planar parallel with a XY-plane such that the probe may deflect in a Z-direction; whereby the rib deflects in the X-direction in response to a force applied in the X-direction to the probe tip, and the probe deflects in the Z-direction in response to a force applied in the Z-direction to the probe tip. - View Dependent Claims (27, 28, 29, 30, 31)
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Specification