Lateral motion MEMS Switch

• US 6,798,315 B2
• Filed: 12/04/2001
• Issued: 09/28/2004
• Est. Priority Date: 12/04/2001
• Status: Expired due to Fees

• Current Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Original Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Inventors: Schaefer, Timothy M.
• Primary Examiner(s): Lee, Benny
• Assistant Examiner(s): GLENN, KIMBERLY E
• Application Number:
  US10/006,865
• Publication Number:
  US 20030102936A1
• Time in Patent Office: 1,029 Days
• Field of Search: 333/101-108, 333/262, 200/244, 200/253.1, 200/329, 200/181, 361/78, 361/80, 361/106, 361/185
• US Class Current: 333/105
• CPC Class Codes: B81B 2203/0136 Comb structures
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• 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: H01H 1/06 characterised by the shape or structure of the contact-making surface, e.g. grooved
• CPC Class Codes: H01H 2001/0078 with parallel movement of the movable contact relative to the substrate
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

A micro-electrical-mechanical system (MEMS) switch. The switch includes a compliant spring that supports a contact shuttle for movement in a lateral direction generally parallel to the substrate and biases the contact shuttle to a normally open switch state position. A plurality of moving electrodes are coupled to the contact shuttle. A plurality of fixed electrodes are interleaved with the moving electrodes. The moving electrodes and the fixed electrodes have generally planar major surfaces perpendicular to the plane of the substrate. Electrostatic forces developed between the fixed and moving electrodes cause the contact shuttle to move to a closed switch state position in response to the application of an actuation voltage. The moving direction of the moving electrodes and the contact shuttle is along a longitudinal axis parallel to the substrate and perpendicular to the planar major surfaces of the electrodes.

Claims

1. A MEMS switch comprising:

a substrate defining a plane;

first and second switch contacts;

a contact shuttle that is movable in a linear path between first and second switch state positions with respect to the switch contacts;

a spring biasing the contact shuttle to the first switch state position;

a plurality of moving electrodes coupled to the contact shuttle and having generally planar major surfaces perpendicular to the plane of the substrate; and

a plurality of fixed electrodes, each located interleaved with and adjacent to one of the moving electrodes, having generally planar major surfaces perpendicular to the plane of the substrate, wherein in response to the application of an electric actuation voltage, electrostatic forces develop between the moving and fixed electrodes causing the moving electrodes to move along an axis parallel to the plane of the substrate and perpendicular to the planar major surfaces of the electrodes, thereby forcing the contact shuttle to move to the second switch state position along the axis parallel to the plane of the substrate and perpendicular to the planar major surfaces of the electrodes.

2. The MEMS switch of claim 1 wherein the contact shuttle is electrically isolated from the moving and fixed electrodes.

3. The MEMS switch of claim 2 wherein the contact shuttle includes:

a polysilicon base;

a metal contact member on the base; and

native oxide between the base and metal contact member.

4. The MEMS switch of claim 1 wherein the spring includes:

a relatively rigid member connected to the contact shuttle; and

at least one resilient member connected to the relatively rigid member.

5. The MEMS switch of claim 4 wherein the moving electrodes are connected to and extend from the relatively rigid member of the spring.

6. The MEMS switch of claim 5 wherein the moving electrodes include moving electrodes connected to and extending from opposite sides of the relatively rigid member.

7. The MEMS switch of claim 6 wherein the spring includes a plurality of resilient members connected to and extending from opposite sides of the relatively rigid member.

8. The MEMS switch of claim 1 wherein the fixed electrodes and moving electrodes have major surfaces facing one another.

9. The MEMS switch of claim 1 wherein the spring includes:

a relatively rigid member connected to the contact shuttle and movable in the linear path; and

at least two resilient members connected to and extending from the rigid member.

10. The MEMS switch of claim 9 wherein the resilient members are parallel to the plane of the substrate.

11. The MEMS switch of claim 10 wherein the moving electrodes are connected to and extend from opposite sides of the rigid member.

12. The MEMS switch of claim 11 wherein the moving electrodes include at least two electrodes on both opposite sides of the rigid member.

13. The MEMS switch of claim 12 wherein the spring is a parallelogram structure.

14. The MEMS switch of claim 1 wherein the spring is parallelogram structure including:

a relatively rigid member connected to the contact shuttle and movable in the linear path;

first and second end members extending from the rigid member at spaced-apart locations;

a first side member connected to and extending between the first and second end members on a first side of the rigid member;

a second side member connected to and extending between the first and second end members on a second side of the rigid member;

a first support arm having a first end connected to the first side member and a second end connected to the substrate; and

a second support arm having a first end connected to the second side member and a second end connected to the substrate.

15. The MEMS switch of claim 14 wherein:

the second end of the first support arm is located between the rigid member and the first side member; and

the second end of the second support arm is located between the rigid member and the second side member.

16. The MEMS switch of claim 1 wherein the first and the second switch contacts are positioned adjacent to but are electrically isolated from one another to form a concave gap that opens toward the contract shuttle.

17. The MEMS switch of claim 16 wherein the contact shuttle is a convex member that is sized and shaped to extend into the concave gap between the first and the second switch contacts.

18. The MEMS switch of claim 16 wherein the first and the second switch contacts have planar faces to form a V-shaped gap that opens toward the contract shuttle.

19. The MEMS switch of claim 18 wherein the contact shuttle is a triangularly-shaped member that is sized and shaped to extend into the V-shaped gap between the first and the second switch contacts.

20. A MEMS switch, including:

a substrate;

a contact shuttle movable with respect to the substrate between switch state positions;

a plurality of moving electrodes coupled to the contact shuttle at spaced-apart locations and having generally planar major surfaces facing each other to form a comb structure; and

a plurality of fixed electrodes coupled to the substrate at spaced-apart locations and having generally planar major surfaces facing each other to form a comb structure, the fixed electrode comb structure interleaved with the moving electrode comb structure, wherein in response to the application of an electric actuation voltage, electrostatic forces develop between the moving and fixed electrodes causing the major surfaces of the moving electrodes to move with respect to the major surfaces of the fixed electrodes, thereby forcing the contact shuttle to move between the switch state positions along a longitudinal axis parallel to the substrate and perpendicular to the planar major surfaces of the electrodes.

21. The MEMS switch of claim 20 and further including:

a member connected to the contact shuttle; and

wherein the moving electrodes are mounted to the member.

22. A MEMS switch, including:

switch contacts;

a driven member;

a contact shuttle connected to the driven member and movable between switch state positions with respect to the switch contacts; and

an isolation mount connecting the contact shuttle to the driven member, including;

a retainer member fixedly connected to the other of the contact shuttle and driven member; and

an engaging member fixedly connected to the other of the contact shuttle and driven member, the engaging member free from fixed connection to but retained by the retainer member, and wherein adjacent surfaces of the contact shuttle, retainer member and engaging member are coated with an oxide insulator.

23. The MEMS switch of claim 22 wherein the contact shuttle includes:

a polysilicon base;

a metal contact member on the base; and

native oxide between the bast and metal contact member.

24. A MEMS switch comprising:

first and second switch contacts positioned adjacent to and electrically isolated from one another to form a concave gap;

a convex contact shuttle sized and shaped to extend into the concave gap and movable in a linear path between first and second switch state positions with respect to the switch contacts; and

an electrostatic actuating mechanism for driving the contact shuttle between the first and the second switch state positions.

25. The MEMS switch of claim 24 wherein the first and the second switch contacts have planar faces to form a V-shaped gap that opens toward the contract shuttle.

26. The MEMS switch of claim 25 wherein the contact shuttle is a triangularly-shaped member that is sized and shaped to extend into the V-shaped gap between the first and the second switch contacts.

27. The MEMS switch of claim 24 wherein the contact shuttle includes:

a polysilicon base;

a metal contact member on the base; and

native oxide between the base and metal contact member.

28. A MEMS actuator comprising:

a substrate defining a plane;

a plurality of moving electrodes having generally planar major surfaces perpendicular to the plane of the substrate;

a plurality of fixed electrodes, each located interleaved with and adjacent to one of the moving electrodes, having generally planar major surfaces perpendicular to the plane of the substrate, wherein in response to the application of an electric actuation voltage, electrostatic forces develop between the moving and fixed electrodes causing the moving electrodes to move along an axis parallel to the plane of the substrate and perpendicular to the planar major surfaces of the electrodes; and

at least one spring for biasing the movable comb structure to a rest position upon removal of the electric actuation voltage.