Multi-dimensional precision micro-actuator

• US 5,375,033 A
• Filed: 01/06/1993
• Issued: 12/20/1994
• Est. Priority Date: 04/14/1992
• Status: Expired due to Term

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Inventors: MacDonald, Noel C.
• Primary Examiner(s): Reynolds, Bruce A.
• Assistant Examiner(s): Mills, Gregory L.
• Application Number:
  US08/002,500
• Time in Patent Office: 713 Days
• Field of Search: 156/628, 156/630, 156/625, 250/306, 250/307, 361/311, 361/312, 361/313, 361/278, 361/281, 361/290, 361/289, 361/296, 310/309, 333/235
• US Class Current: 361/281
• CPC Class Codes: B82Y 35/00 Methods or apparatus for measurement or analysis of nanostructures
• CPC Class Codes: G01Q 10/04 Fine scanning or positioning
• CPC Class Codes: H01H 1/0094 Switches making use of nanoelectromechanical systems [NEMS]
• CPC Class Codes: H01H 2001/0068 with multi dimensional movement, i.e. the movable actuator performing movements in at least two different directions
• CPC Class Codes: H01H 2001/0078 with parallel movement of the movable contact relative to the substrate
• CPC Class Codes: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type

Abstract

Mechanically movable microstructure fabricated from a single crystal such as silicon and actuator structures for providing a high degree of controlled, precision motion of nanometer-scale variable impedances.

Claims

1. A precision microactuator for movable microstructures, comprising:

an integrated circuit wafer having a cavity;

a cantilevered beam having a longitudinal axis and having a first end fixed to said wafer and a second remote end extending into said cavity;

actuator means within said cavity between said first and second ends of said beam and dividing said beam into relatively movable, axially aligned, longitudinal segments;

means for applying a potential across said actuator means to cause said relatively movable beam segments to move with respect to each other to cause said remote end of said beam to move along said longitudinal axis with respect to said fixed end to vary the length of the beam; and

variable impedance means within said cavity and connected to said remote end of said beam for adjustment in response to application of said potential to said actuator means.

2. The microactuator of claim 1, wherein said variable impedance means comprises at least a first pair of capacitor plates, one plate of said pair being integrated with said remote end of said beam.

3. The microactuator of claim 2, wherein said actuator means comprises a second pair of capacitor plates dividing said beam into a corresponding plurality of relatively movable longitudinal segments.

4. The microactuator of claim 3 wherein said actuator means further includes flexible spring bias means connected to said second pair of capacitor plates.

5. The microactuator of claim 4, wherein said spring bias means comprises end spacer means between said second pair of capacitor plates.

6. The microactuator of claim 4, wherein said spring bias means comprises connector means connected to said beam segments.

7. The microactuator of claim 4, wherein said spring bias means comprises electrically insulating end spacer means between said second pair of capacitor plates.

8. The microactuator of claim 4, wherein said spring bias means comprises electrically conductive connector means connected to said beam segments.

9. The microactuator of claim 8, wherein said spring bias means further includes electrically insulating flexible end spacer means between said second pair of capacitor plates.

10. The microactuator of claim 1, wherein said means for applying a potential across said actuator means includes electrically conductive connector means connected between selected beam segments and electrical circuit means on said wafer.

11. The microactuator of claim 10, wherein said electrically conductive connector means comprises flexible connector arms which mechanically support and spring bias said beam segments and actuator means.

12. The microactuator of claim 1, wherein said variable impedance means comprises a first pair of capacitor plates having at least one plate integral with said remote end of said beam and wherein said actuator means comprises a plurality of pairs of capacitor drive plates spaced along said beam and dividing said beam into a corresponding plurality of relatively movable longitudinal segments.

13. The microactuator of claim 12 wherein said beam, said variable impedance means, said actuator means, and said integrated circuit wafer are fabricated from a single-crystal, electrically conductive substrate to form a cantilevered microstructure, the beam, the actuator means, and the variable impedance means being integrally formed from the substrate.

14. The microactuator of claim 13, further including a layer of electrically insulating material on selected surfaces of said capacitor drive plates.

15. The microactuator of claim 14, further including flexible spring bias means fabricated from said electrically insulating material and connected between opposed capacitor drive plates for maintaining said drive plates in a predetermined spaced relationship.

16. The microactuator of claim 15, further including electrically conductive connector means connected to corresponding segments of said beam, said connector means forming a part of said cantilevered microstructure.

17. The actuator of claim 16, wherein said connector means are integrally formed from the substrate.

18. The microactuator of claim 1, wherein said variable impedance means comprises first and second interdigitated capacitor plates, the first capacitor plate being connected to said remote end of said beam for motion with said beam with respect to the second capacitor plate.

19. The microactuator of claim 18, wherein said second capacitor plate of said variable impedance means is fixed.

20. The microactuator of claim 18 wherein said first and second capacitor plates of said variable impedance are connected between relatively movable segments of said beam.

21. A precision microactuator for movable microstructures, comprising:

an integrated circuit wafer having a cavity;

first and second axially aligned cantilevered beams, each beam having an axis, a first end affixed to said wafer and a second, remote, axially aligned end extending into said cavity, the remote ends of said beams being spaced apart;

first and second actuators within said cavity and interposed between the first and second ends of said first and second beams, respectively, to divide each beam into relatively movable, axially aligned longitudinal segments;

means for applying selected potentials across each said actuators to selectively produce relative axial motion of said longitudinal segments for each of said beams to selectively vary the length of each beam; and

a variable impedance connected between the remote ends of said beams, whereby variation of the length of either of said beams will vary said impedance.

22. The microactuator of claim 21, wherein said variable impedance comprises first and second capacitor plates integrally formed on respective remote ends of said first and second beams for relative motion upon selective variation of the lengths of said beams, said capacitor plates forming a variable capacitor.