Microfabricated Mechanical Frequency Multiplier

• US 20080024038A1
• Filed: 09/04/2007
• Published: 01/31/2008
• Est. Priority Date: 01/18/2005
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Culpepper, Martin, Chen, Shih-Chi
• Granted Patent: US 7,882,701 B2
• Time in Patent Office: Days
• US Class Current: 310/317
• CPC Class Codes: F03G 7/06 using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like using thermal expansion of non-vaporising liquids F01K
• CPC Class Codes: H02K 2201/18 Machines moving with multiple degrees of freedom
• CPC Class Codes: H02N 10/00 Electric motors using thermal effects motors using expansion or contraction of bodies due to heating or cooling F03G7/06

Abstract

A high-bandwidth MEMS actuation system includes actuator pairs coupled in parallel to a stage, each actuator energizable in a drive direction against a bias to an energized position, and movable upon deenergization, to the rest position to define an actuation cycle. The actuators are asymmetric, with an energization frequency greater than a bias frequency, and are opposably coupled to one another. A pulse generator alternately transmits pulses to the actuators, at an alternation frequency greater than the bias frequency. The pulse generator transmits the energization pulses to each of the actuator pairs sequentially at a sequence frequency greater than the cycle frequency. The actuators are each movable from energized to rest positions faster than the bias frequency, and the actuator pairs are sequentially energizable faster than the cycle frequency, wherein the stage is movable in one degree of freedom at a bandwidth of at least four times the cycle frequency.

Claims

1. A high-bandwidth micro electro-mechanical system (MEMS) actuation system comprising:

a stage;

at least two actuator pairs coupled in parallel to said stage;

said actuator pairs each including at least first and second controlled input bi-directional semiconductor actuators;

said actuators each being energizable to move in a drive direction against a bias from a rest position to an energized position, and each being movable by the bias to the rest position upon deenergization, wherein movement from the rest position to the energized position and back to the rest position defines an actuation cycle;

said actuators being asymmetric, wherein a maximum energization frequency of movement from the rest to the energized positions is greater than a maximum bias frequency of movement from the energized to the rest positions;

said first and second actuators being opposably coupled to one another, wherein drive directions of said actuators oppose one another;

a pulse generator coupled to said actuators of each actuator pair;

said pulse generator configured to alternately transmit energization pulses to said actuators of each actuator pair at an alternation frequency greater than said bias frequency of movement;

said pulse generator configured to transmit said energization pulses to each of said actuator pairs sequentially at a sequence frequency greater than a frequency of said actuation cycle;

wherein said actuators are each movable from their energized positions to their rest positions at a frequency greater than said bias frequency of movement, said actuator pairs are sequentially energizable at a sequence frequency greater than said cycle frequency, and said stage is movable in a single degree of freedom at a bandwidth of at least four times said cycle frequency.

2. The actuation system of claim 1, wherein said stage is movable in a single degree of freedom at a bandwidth of at least ten times said cycle frequency.

3. The actuation system of claim 1, wherein said stage is moveable in a plurality of degrees of freedom.

4. The actuation system of claim 1, wherein said actuators comprise microfabricated actuators.

5. The actuation system of claim 4, being fabricated from a micro-scale structural material selected from the group consisting of silicon, silicon dioxide, gallium arsenide, aluminum nitride, photoresist, SU8, metals and combinations thereof.

6. The actuation system of claim 4, wherein said actuators are coupled to one another by at least one beam.

7. The actuation system of claim 6, wherein said beam is coupled to a stage with at least one flexure hinge, wherein energization of said actuators is configured to generate controlled movement of said stage.

8. The actuation system of claim 7, wherein said actuators, said beam, said stage, and said flexure hinge are disposed within a semiconductor layer.

9. The actuation system of claim 8, wherein said actuators are coupled to a plurality of said beams at spaced locations thereon.

10. The actuation system of claim 7, wherein said first and second actuators extend in a planar direction within a first planar layer, and the actuation system further comprises at least a third controlled input bi-directional actuator extending within a second planar layer;

said first layer being superposed with said second layer, and said third actuator being coupled to said beam;

wherein selective, alternating energization of said actuators is configured to generate controlled movement of said stage in and out of the planar direction.

11. The actuation system of claim 10, wherein said first and second controlled input actuators are superposed with said third controlled input actuators.

12. The actuation system of claim 10, wherein said first layer and said second layer are coupled to one another by an intermediary layer.

13. The actuation system of claim 12, wherein said intermediary layer extends intermittently in the planar direction, so that said first and second layers are coupled to one another at spaced locations thereon.

14. The actuation system of claim 10, wherein:

said first, second, and third actuators are selectively energizable to effect longitudinal expansion thereof;

relative actuation between individual ones of actuators spaced in said planar direction relative to one another is configured to generate controlled movement of said stage within the planar direction;

relative actuation between individual ones of actuators spaced orthogonally to said planar direction relative to one another is configured to generate controlled movement of said stage out of the planar direction; and

the position of said stage is adjustable in each of six degrees of freedom.

15. The actuation system of claim 14, wherein said first, second, and third controlled input actuators comprise thermal actuators.

16. The actuation system of claim 14 wherein the relative position between said stage and ground is adjustable with a translational resolution in increments as small as one Angstrom.

17. The actuation system of claim 14 wherein the relative position between said stage and ground is adjustable with a rotational resolution in increments of less than about 5 micro radians.

18. The actuation system of claim 10, wherein said stage comprises an other stage disposed within said second planar layer.

19. The actuation system of claim 18, wherein said at least one beam comprises at least one other beam extending in the planar direction within said second layer.

20. The actuation system of claim 19, wherein said other beam comprises a plurality of other beams disposed within said second layer.

21. The actuation system of claim 20, comprising a plurality of second flexure hinges disposed within said second layer, coupled to said other stage and to said other beams.

22. The actuation system of claim 21, wherein a plurality of said third actuators are coupled to said other beams at spaced locations thereon.

23. A method for actuation of a first component relative to a second component, said method comprising:

providing the actuation system of claim 7;

fastening the first component to the stage; and

with said pulse generator, alternately transmitting energization pulses to said actuators at an alternation frequency greater than the bias frequency of movement to effect a change in position of the first component relative to the second component.

24. A method for actuation, comprising:

(a) coupling at least two actuator pairs in parallel to a stage, the actuator pairs including at least first and second bi-directional micro- or nano-scale sized actuators, each energizable to move in a drive direction against a bias from a rest position to an energized position, and each being movable by the bias to the rest position upon deenergization, wherein movement from the rest position to the energized position and back to the rest position defines an actuation cycle, the actuators being asymmetric, wherein a maximum energization frequency of movement from the rest to the energized positions is greater than a maximum bias frequency of movement from the energized to the rest positions;

(b) opposably coupling the first and second actuators to one another, wherein drive directions of said actuators oppose one another;

(c) coupling a pulse generator to the to said actuators of each actuator pair;

(d) with the pulse generator, alternately transmitting energization pulses to the actuators of each actuator pair at an alternation frequency greater than the bias frequency of movement;

(e) with the pulse generator, transmitting said energization pulses to each of said actuator pairs sequentially at a sequence frequency greater than a frequency of the actuation cycle;

wherein the actuators are each movable from their energized positions to their rest positions at a frequency greater than the bias frequency of movement, said actuator pairs are sequentially energizable at a sequence frequency greater than the cycle frequency, and the stage is movable in a single degree of freedom at a bandwidth of at least four times the cycle frequency.

25. The method of claim 24, wherein said actuators are selected from the group consisting of electro-mechanical, magnetostrictive, thermomechanical, and active carbon nanotube actuators.

26. A high-bandwidth micro electro-mechanical system (MEMS) actuation system comprising:

stage means;

at least two actuator pairs coupled in parallel to said stage means;

said actuator pairs each including at least first and second controlled input bi-directional actuation means;

said actuation means each being energizable to move in a drive direction against a bias from a rest position to an energized position, and each being movable by the bias to the rest position upon deenergization, wherein movement from the rest position to the energized position and back to the rest position defines an actuation cycle;

said actuation means being asymmetric, wherein a maximum energization frequency of movement from the rest to the energized positions is greater than a maximum bias frequency of movement from the energized to the rest positions;

said first and second actuation means being opposably coupled to one another, wherein drive directions of said actuators oppose one another;

a pulse generation means coupled to said actuators of each actuator pair;

said pulse generation means configured to alternately transmit energization pulses to said actuation means of each actuator pair at an alternation frequency greater than said bias frequency of movement;

said pulse generation means configured to transmit said energization pulses to each of said actuator pairs sequentially at a sequence frequency greater than a frequency of said actuation cycle;

wherein said actuation means are each movable from their energized positions to their rest positions at a frequency greater than said bias frequency of movement, said actuator pairs are sequentially energizable at a sequence frequency greater than said cycle frequency, and said stage means is movable in a single degree of freedom at a bandwidth of at least four times said cycle frequency.

27. The system of claim 26, wherein said actuation means are selected from the group consisting of nano-scale and micro-scale sized actuators.

28. The system of claim 27, wherein said actuation means are selected from the group consisting of electro-mechanical actuators, magnetostrictive actuators, thermomechanical actuators, active carbon nanotube actuators, and combinations thereof.