Inertial or resonating sensor in surface technology, with out of plane detection by strain gauge

• US 8,371,166 B2
• Filed: 01/22/2010
• Issued: 02/12/2013
• Est. Priority Date: 01/23/2009
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: Robert, Philippe
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US12/692,051
• Publication Number:
  US 20100186510A1
• Time in Patent Office: 1,117 Days
• Field of Search: 735/142.9, 735/143.2, 735/040.4, 735/040.2, 735/041.2, 735/041.4, 735/041.6
• US Class Current: 73/514.29
• CPC Class Codes: G01C 19/5656 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5769 Manufacturing; Mounting; Housings
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/097 by vibratory elements

Abstract

A MEMS surface sensor, including: a substrate, a surface of which defines a substrate plane; a first zone having a first thickness, of which two surfaces form a first plane and a second plane parallel in relation to one another and to the substrate plane, first zone forming at least one mobile mass that moves in a direction out of the substrate plane; and a second zone, linked to a fixed zone of the substrate, the second zone forming at least a pivot link of the mobile mass in relation to said substrate, and having a thickness less or equal to that of the mobile mass and being linked to the mobile mass, an axis of the pivot link being between the first plane and the second plane, and parallel to the first plane and the second plane.

Claims

1. A MEMS surface sensor, comprising:

a substrate, a surface of which defines a substrate plane;

a first zone having a first thickness, of which two surfaces form a first plane and a second plane parallel in relation to one another and to the substrate plane, first zone forming at least one mobile mass that moves in a direction out of the substrate plane;

a second zone, linked to a fixed zone of the substrate, the second zone forming at least a pivot link of the mobile mass in relation to said substrate, and having a thickness less or equal to that of the mobile mass and being linked to the mobile mass, an axis of the pivot link being between the first plane and the second plane, and parallel to the first plane and the second plane, the mobile mass moving in the direction out of the substrate plane about the axis of the pivot link, the second zone having, along a direction perpendicular to the substrate plane, a lower part and an upper part, at least one of the upper part of the second zone and the lower part of the second zone being in the first plane or in the second plane common to the first and second zones;

a third zone of a lesser thickness than that of the second zone, forming at least a suspended strain gauge that detects movement of the mobile mass around the axis of the pivot link in the direction out of the substrate plane, the third zone having, along a direction perpendicular to the substrate plane, a lower part and an upper part, one of the upper part of the third zone or the lower part of the third zone being in a plane common with the first zone or with the second zone, and the third zone

extends in a plane parallel to the substrate plane not containing the axis of the pivot link,

extends perpendicular to a rotation axis of the pivot link, and

is linked to the mobile mass on one side and to the substrate on another.

2. The sensor according to claim 1, wherein the second zone:

has a width, along a direction of the pivot axis H, less than a width of the mobile mass along the direction of the pivot axis;

or includes two extended arms, disposed on either side of the mobile mass or in a gap made in this mobile mass.

3. The sensor according to claim 1, wherein the mobile mass has a thickness strictly greater than that of the second zone.

4. The sensor according to claim 1, wherein the third zone and the first zone:

have a common plane, which is the second plane of the mobile mass and the third zone and the first zone are situated on a same side in relation to the common plane,

or have a common plane, which is the second plane of the mobile mass, and is situated on both sides of the common plane.

5. The sensor according to claim 1, wherein the axis of the pivot link is in a plane parallel to the first plane and to the second plane of the sensor, and extends through a center of gravity of the mobile mass.

6. The sensor according to claim 1, wherein application points of strains produced by the mobile mass on each strain gauge being in a perpendicular plane to each of the first plane and second plane and including the axis of the pivot link.

7. The sensor according to claim 1, wherein the third zone includes at least two strain gauges, situated in an anti-symmetrical fashion in relation to each other and in relation:

to a plane perpendicular to the first and second planes of the mobile mass and including the axis of the pivot link,

and to a plane perpendicular to the axis of the pivot link.

8. The sensor according to claim 1, wherein the strain gauge includes a piezo-resistant material.

9. The sensor according to claim 8, wherein the strain gauge is single branch or double branch.

10. The sensor according to claim 1, wherein the strain gauge includes at least a detection resonator, including at least a vibrating blade vibrating in a plane parallel to the first and second planes, a means for exciting the vibrating blade, and a means for detecting the vibration.

11. The sensor according to claim 10, wherein the means for exciting the vibrating blade is electrostatic, and the sensor includes electrostatic means for detecting resonance.

12. The sensor according to claim 11, wherein the strain gauge includes at least one electrode placed, in relation to the vibrating blade, in a direction of the vibration.

13. The sensor according to claim 10, wherein the strain gauge includes piezo-resistive means for resonance detection, disposed on the vibrating blade.

14. The sensor according to claim 1, also including means for triggering movement of the mobile mass.

15. The sensor according to claim 14, wherein the means for triggering movement of the mobile mass includes:

an electrode present on, or in, the substrate with regard a side of the mobile mass,

or a layer of conductive material disposed on the mobile mass and linked to the substrate, electrically insulated from the mobile mass by an insulation layer, forming a bimetal with the mobile mass,

or a layer of piezo-electric material disposed on the mobile mass and linked to the substrate, electrically insulated from the mobile mass by an insulation layer.

16. The sensor according to claim 1, comprising, on a surface of the mobile mass, means for selecting a molecule capable of being surface adsorbed or absorbed.