Lateral piezoelectric microelectromechanical system (MEMS) actuation and sensing device

• US 7,420,318 B1
• Filed: 03/20/2006
• Issued: 09/02/2008
• Est. Priority Date: 03/20/2006
• Status: Expired due to Fees

• Current Assignee: The United States Of America As Represented By The Secretary Of The Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Pulskamp, Jeffrey S.
• Primary Examiner(s): Dougherty; Thomas M.
• Assistant Examiner(s): Gordon; Bryan P
• Application Number:
  US11/387,078
• Time in Patent Office: 897 Days
• Field of Search: 310/311, 310/316.01, 310/332, 347/71, 347/72, 367/160, 367/161, 367/162
• US Class Current: 310/328
• CPC Class Codes: H10N 30/2044 having multiple segments mechanically connected in series, e.g. zig-zag type
• CPC Class Codes: H10N 30/2045 adapted for in-plane bending displacement

Abstract

A microelectromechanical system (MEMS) device comprises a substrate; an anchored end connected to the substrate; a free end comprising an end effector opposite to the anchored end; a spring attached to the end effector; multiple actuation beams; multiple connection beams adapted to connect the multiple actuation beams to one another; and an actuator/sensor comprising a first electrode; a piezoelectric layer over the first electrode; and a set of second electrodes over the piezoelectric layer, wherein the set of second electrodes being defined by a transverse gap therebetween. Each of the multiple actuation beams comprises two sets of the second electrodes. The set of second electrodes comprise an extensional electrode and a contraction electrode. One of the sets of second electrodes is actuated asymmetrically with respect to a first plane resulting in a piezoelectrically induced bending moment arm in a lateral direction that lies in a second plane.

Claims

1. A microelectromechanical system (MEMS) device comprising:

a substrate;

an anchored end connected to said substrate;

a free end positioned opposite to said anchored end;

a central gap separating said anchored end from said free end and positioned along a central longitudinal axis of said MEMS device; and

multiple actuation beams each having a longitudinal axis positioned transverse to said central longitudinal axis of said central gap and said MEMS device, wherein said multiple actuation beams comprise a first set of multiple actuation beams and a second set of multiple actuation beams positioned on opposite sides of said central gap, wherein said central gap separates said first set of multiple actuation beams from said second set of multiple actuation beams, and wherein each actuation beam comprises;

a first electrode;

a piezoelectric layer over said first electrode; and

multiple sets of second electrodes over said piezoelectric layer, wherein each of said sets of second electrodes being defined by a transverse gap there between, and wherein one of said sets of second electrodes are actuated asymmetrically with respect to a first plane resulting in a piezoelectrically induced bending moment arm in a lateral direction that lies in a second plane.

2. The device of claim 1, all the limitations of which are incorporated herein by reference, further comprising:

an end effector positioned at said free end and opposite to said anchored end; and

a spring attached to said end effector, wherein said spring does not directly contact said multiple actuation beams.

3. The device of claim 1, all the limitations of which are incorporated herein by reference, further comprising:

multiple connection beams adapted to connect said multiple actuation beams to one another, wherein each connection beam is positioned substantially perpendicular to said multiple actuation beams, and wherein said each connection beam is positioned substantially parallel to said central gap.

4. The device of claim 3, all the limitations of which are incorporated herein by reference, wherein each of said multiple actuation beams comprise two sets of said second electrodes.

5. The device of claim 1, all the limitations of which are incorporated herein by reference, wherein said set of second electrodes comprise an extensional electrode and a contraction electrode.

6. The device of claim 2, all the limitations of which are incorporated herein by reference, wherein said spring comprises a residual stress deformation mitigation spring adapted to prevent out-of-plane stress deformation of said each actuation beam.

7. The device of claim 2, all the limitations of which are incorporated herein by reference, wherein said spring comprises a residual stress deformation mitigation spring adapted to restrict translational motion of said end effector to be within said second plane, and wherein said first plane is transverse to said second plane.

8. A microelectromechanical system (MEMS) device comprising:

at least one actuation beam comprising;

a continuous lower electrode;

a piezoelectric layer over said lower electrode; and

at least one pair of upper electrodes over said piezoelectric layer;

an anchored end connected to said actuation beam;

a free end opposite to said anchored end, wherein said free end comprises an end effector; and

a spring member connected to said free end, wherein said spring member does not directly contact said at least one actuation beam, and wherein said spring member flanks lateral sides of said end effector.

9. The device of claim 8, all the limitations of which are incorporated herein by reference, further comprising connection beams adapted to connect multiple actuation beams to one another, wherein each connection beam is positioned substantially perpendicular to said multiple actuation beams.

10. The device of claim 8, all the limitations of which are incorporated herein by reference, wherein said actuation beam comprises multiple pairs of said upper electrodes.

11. The device of claim 8, all the limitations of which are incorporated herein by reference, wherein said pair of upper electrodes comprises a first electrode and a second electrode, and wherein said pair of upper electrodes comprising a gap between said first electrode and said second electrode.

12. The device of claim 8, all the limitations of which are incorporated herein by reference, wherein said pair of upper electrodes comprise an extensional electrode and a contraction electrode.

13. The device of claim 8, all the limitations of which are incorporated herein by reference, wherein said spring member comprises a residual stress deformation mitigation spring adapted to prevent out-of-plane stress deformation of said actuation beam.

14. The device of claim 10, all the limitations of which are incorporated herein by reference, wherein one of said multiple pairs of upper electrodes are actuated asymmetrically with respect to a first plane resulting in a piezoelectrically induced bending moment arm in a lateral direction that lies in a second plane.

15. The device of claim 14, all the limitations of which are incorporated herein by reference, wherein said spring member comprises a residual stress deformation mitigation spring adapted to restrict translational motion of said end effector to be within said second plane, and wherein said first plane is transverse to said second plane.

16. The device of claim 8, all the limitations of which are incorporated herein by reference, further comprising a silicon substrate attached to said anchored end.

17. A microelectromechanical system (MEMS) device having a first end and a second end, said device comprising:

a sensor positioned in between said first end and said second end and comprising;

a piezoelectric layer; and

multiple electrodes sandwiching said piezoelectric layer, said multiple electrodes comprising a continuous first electrode attached to a first side of said piezoelectric layer and at least one pair of second electrodes attached to a second side of said piezoelectric layer, wherein said pair of second electrodes comprises a primary electrode and a secondary electrode defined by a transverse gap therebetween;

a substrate anchored to said first end;

an end effector attached to said second end; and

a spring member attached to lateral sides of said end effector and spaced apart from said sensor,

wherein said multiple electrodes are adapted to receive voltage, said voltage causing said end effector to laterally deflect in a geometric plane of said substrate.

18. The device of claim 17, all the limitations of which are incorporated herein by reference, further comprising:

multiple actuation beams; and

multiple connection beams adapted to connect said multiple actuation beams to one another,

wherein each of said multiple actuation beams comprise two pairs of said second electrodes.

19. The device of claim 17, all the limitations of which are incorporated herein by reference, wherein said primary electrode is an extensional electrode and said secondary electrode is a contraction electrode.

20. The device of claim 17, all the limitations of which are incorporated herein by reference, wherein said spring member comprises a residual stress deformation mitigation spring adapted to prevent out-of-plane stress deformation of said device.

21. The device of claim 17, all the limitations of which are incorporated herein by reference, wherein one of said pairs of second electrodes are actuated asymmetrically with respect to a first plane resulting in a piezoelectrically induced bending moment arm in a lateral direction that lies in a second plane.

22. The device of claim 21, all the limitations of which are incorporated herein by reference, wherein said spring member comprises a residual stress deformation mitigation spring adapted to restrict translational motion of said end effector to be within said second plane, and wherein said first plane is transverse to said second plane.