High-output MEMS accelerometer

• US 9,581,614 B2
• Filed: 06/02/2014
• Issued: 02/28/2017
• Est. Priority Date: 06/02/2014
• Status: Expired due to Fees

• Current Assignee: PCB Piezotronics of North Carolina, Inc. (Amphenol Corporation)
• Original Assignee: Meggitt PLC
• Inventors: Kwa, Tom
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US14/293,992
• Publication Number:
  US 20150346235A1
• Time in Patent Office: 1,002 Days
• Field of Search: 735/143.3, 735/143.4, 735/143.6, 735/143.8
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2203/0109 Bridges
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: G01P 15/09 by piezoelectric pick-up
• CPC Class Codes: G01P 15/12 by alteration of electrical resistance G01P15/0897, G01P15/105 take precedence
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 2015/0831 the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration

Abstract

A MEMS acceleration sensor is provided. In one embodiment, the MEMS acceleration sensor comprises: a frame; a first proofmass located within the frame, the first proofmass including a left side, right side, top, and bottom; an axis running from the left side to the right side at about a median point between the top and bottom; a first flexure running along the axis and coupling the left side to the frame; a second flexure running along the axis and coupling the right side to the frame; a first channel that extends from the bottom up past the axis to a first channel end; a second channel that extends from the top down past the axis to a second channel end; a second proofmass located within the first channel and coupled to the first proofmass via a first hinge and a first gauge at the first channel end and coupled to the frame at the bottom via a second hinge and a second gauge; and a third proofmass located within the second channel and coupled to the first proofmass via a third hinge and a third gauge at the second channel end and coupled to the frame at the top via a fourth hinge and a fourth gauge.

Claims

1. A MEMS acceleration sensor comprising:

a frame;

a first proofmass located within the frame, the first proofmass including a left side, a right side, a top, and a bottom;

an axis running from the left side to the right side at about a median point between the top and the bottom;

a first flexure running along the axis and coupling the left side to the frame;

a second flexure running along the axis and coupling the right side to the frame;

a first channel that extends from the bottom up past the axis to a first channel end;

a second channel that extends from the top down past the axis to a second channel end;

a second proofmass located within the first channel and coupled to the first proofmass via a first hinge and a first gauge at the first channel end and coupled to the frame at the bottom via a second hinge and a second gauge; and

,

a third proofmass located within the second channel and coupled to the first proofmass via a third hinge and a third gauge at the second channel end and coupled to the frame at the top via a fourth hinge and a fourth gauge.

2. The MEMS acceleration sensor of claim 1, wherein the first proofmass rotates relative to the frame about the axis.

3. The MEMS acceleration sensor of claim 2, wherein the first gauge, the second gauge, the third gauge, and the fourth gauge are made of a piezoresistive material.

4. The MEMS acceleration sensor of claim 3, wherein rotation of the first proofmass about the axis causes a piezoresistive effect in at least one of the first gauge, the second gauge, the third gauge, and the fourth gauge.

5. The MEMS acceleration sensor of claim 1, wherein the second proofmass and the third proofmass are rectangular cuboids.

6. The MEMS acceleration sensor of claim 1, wherein the frame is a stationary rim.

7. The MEMS acceleration sensor of claim 6, wherein the frame has a length of 1.6 millimeters or less and a width of 1.6 millimeters or less.

8. The MEMS acceleration sensor of claim 1, wherein all the hinges are located above a centerline of a thickness of the first proofmass.

9. A MEMS acceleration sensor comprising:

a frame;

an S-shaped proofmass located within the frame;

wherein the S-shaped proofmass includes a top horizontal piece, a center horizontal piece, a bottom horizontal piece, a left side piece that connects the top horizontal piece to the center horizontal piece, and a right side piece that connects the center horizontal piece to the bottom horizontal piece;

wherein the S-shaped proofmass forms a first channel that exists between the top horizontal piece and the center horizontal piece and extends from the frame to the left side piece; and

wherein the S-shaped proofmass forms a second channel that exists between the center horizontal piece and the bottom horizontal piece and extends from the frame to the right side piece;

a first flexure coupling the top horizontal piece to the frame;

a second flexure coupling the bottom horizontal piece to the frame;

a first rectangular cuboid proofmass located within the first channel and coupled to the left side piece of the S-shaped proofmass via a first hinge and a first gauge and coupled to the frame via a second hinge and a second gauge at an opposite end of the first rectangular cuboid proofmass from the first hinge; and

a second rectangular cuboid proofmass located within the second channel and coupled to the right side piece of the S-shaped proofmass via a third hinge and a third gauge and coupled to the frame via a fourth hinge and a fourth gauge at an opposite end of the second rectangular cuboid proofmass from the third hinge.

10. The MEMS acceleration sensor of claim 9, wherein the S-shaped proofmass rotates relative to the frame about an axis running from a top side of the frame to a bottom side of the frame at about a median point between a left side of the frame and a right side of the frame.

11. The MEMS acceleration sensor of claim 10, wherein the first gauge, the second gauge, the third gauge, and the fourth gauge are made of a piezoresistive material.

12. The MEMS acceleration sensor of claim 11, wherein rotation of the S-shaped proofmass about the axis causes a piezoresistive effect in at least one of the first gauge, the second gauge, the third gauge, and the fourth gauge.

13. The MEMS acceleration sensor of claim 9, wherein the frame is a stationary rim.

14. The MEMS acceleration sensor of claim 9, wherein the four hinges are located above a centerline of a thickness of the S-shaped proofmass.

15. A MEMS acceleration sensor comprising:

a frame;

a proofmass located within the frame, the proofmass including at least three vertical blocks and at least two horizontal blocks coupling alternate vertical blocks to form a single proofmass, wherein the proofmass has a left side, a right side, a top, and a bottom;

a first flexure coupling the left side of the proofmass to the frame;

a second flexure coupling the right side of the proofmass to the frame, wherein the first flexure and the second flexure define a pivot axis for the proofmass with respect to the frame;

a first vertical channel that extends from a bottom of the frame up into the proofmass past the pivot axis between two vertical blocks to a first of the at least two horizontal blocks;

a second vertical channel that extends from a top of the frame down into the proofmass past the pivot axis between two vertical blocks to a second of the at least two horizontal blocks;

a first elongated proofmass located within the first vertical channel and coupled to the proofmass via a first hinge and coupled to the frame via a second hinge;

a second elongated proofmass located within the second vertical channel and coupled to the proofmass via a third hinge and coupled to the frame via a fourth hinge; and

at least two gauges wherein the two gauges are located above any two of the four hinges and each gauge is coupled to the same elements as the respective hinge each gauge is located above.

16. The MEMS acceleration sensor of claim 15, wherein the at least two gauges, are made of a piezoresistive material.

17. The MEMS acceleration sensor of claim 16, wherein rotation of the proofmass about the pivot axis causes a piezoresistive effect in at least one of the at least two gauges.

18. The MEMS acceleration sensor of claim 15, wherein the first elongated proofmass and the second elongated proofmass are rectangular cuboids.

19. The MEMS acceleration sensor of claim 15, further comprising four gauges wherein each of the four gauges is located above one of the four hinges and is coupled to the same elements as the respective hinge each gauge is located above.

20. The MEMS acceleration sensor of claim 15, wherein the four hinges are located above a centerline of a thickness of the proofmass.