Microcavity apparatus and systems for maintaining a microcavity over a macroscale area

• US 6,232,546 B1
• Filed: 10/25/1999
• Issued: 05/15/2001
• Est. Priority Date: 07/30/1997
• Status: Expired due to Term

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: DiMatteo, Robert Stephen, Weinberg, Marc Steven, Kirkos, Gregory A.
• Primary Examiner(s): DIAMOND, ALAN D
• Application Number:
  US09/426,542
• Time in Patent Office: 568 Days
• Field of Search: 136/253, 136/201, 136/200, 310/306, 438/57, 438/73, 438/90
• US Class Current: 136/253
• CPC Class Codes: H02S 10/30 Thermophotovoltaic systems photovoltaic cells specially adapted for conversion or sensing of infrared [IR] radiation H01L31/00; thermoelectric devices H10N10/00
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

A microcavity apparatus and systems for maintaining microcavity spacing over a macroscopic area. An application of this invention is a microscale generator. This microscale generator includes a first element for receiving energy; a second element, opposite the first element for transferring energy; at least one panel on either of the first element or the second element, the panel facing the other element; a device for controlling the distance between the at least one panel and the facing element to form a predetermined, sub-micron gap between the panel and the facing element for increasing energy transfer to the element for receiving; and a device, responsive to the energy transfer, for generating electricity.

Claims

1. A microscale generator comprising:

a first element for receiving energy;

a second element, opposite said first element, for transferring energy;

at least one panel on either of the first element or the second element, the panel facing the other element;

a device for controlling the distance between the at least one panel and the facing element to form a sub-micron gap between the panel and the facing element for increasing energy transfer to the element for receiving; and

a converter, responsive to the energy transfer, for generating electricity.

2. The microscale generator of claim 1 in which the device for controlling includes an actuating flexure for urging the panel toward or away from the facing element to form the sub-micron gap, the flexure thermally coupling the panel to the element to which the panel is attached.

3. The microscale generator of claim 2 in which the actuating flexure is disposed below the panel.

4. The microscale generator of claim 2 in which the flexure is disposed about the perimeter of the panel.

5. The microscale generator of claim 2 further including at least one spacing element disposed on the panel between the panel and the facing element for maintaining the sub-micron gap between the panel and the facing element.

6. The microscale generator of claim 5 in which the flexure includes and also serves as a spring to passively urge the panel towards the facing element to maintain the sub-micron gap.

7. The microscale generator of claim 2 in which the flexure includes a piezoelectric actuator responsive to a control circuit which selectively applies a voltage to the actuator for controlling the sub-micron gap.

8. The microscale generator of claim 1 in which the device for controlling includes at least one spacer disposed on the panel between the panel and the facing element for maintaining the sub-micron gap.

9. The microscale generator of claim 8 in which the spacer includes a thermally resistant material.

10. The microscale generator of claim 9 in which the thermally resistant material includes a piezoelectric material.

11. The microscale generator of claim 10 further including a control circuit for activating the spacer to maintain the sub-micron gap.

12. The microscale generator of claim 2 in which the first element is at a higher temperature than the second element.

13. The microscale generator of claim 12 in which the panel is on the first element.

14. The microscale generator of claim 1 in which the first element is at a lower temperature than the second element.

15. The microscale generator of claim 14 in which the panel is on the first element.

16. The microscale generator of claim 1 in which the first element is at the same temperature as the second element.

17. A thermophotovoltaic generator comprising:

a first element for receiving energy;

a second element, opposite the first element, for transferring energy;

at least one panel on either or both of the first element and the second element, the panel facing the other element;

an actuator for controlling the distance between the at least one panel and the facing element to form a sub-micron gap between the panel and the facing element for increasing energy transfer to the element for receiving; and

a converter, responsive to the energy transfer, for generating electricity.

18. The thermophotovoltaic generator of claim 17 in which the actuator is disposed about the perimeter of the panel, thermally coupling the panel to one of the first and second element.

19. The thermophotovoltaic generator of claim 18 in which the actuator is a spring loaded flexure for urging the panel toward the facing element.

20. The thermophotovoltaic generator of claim 17 in which the actuator includes a piezoelectric element responsive to a control circuit which selectively applies a voltage to the piezoelectric actuator for controlling the sub-micron gap.

21. The thermophotovoltaic generator of claim 17 in which the actuator is disposed on the panel, between the panel and the facing element, to form at least one spacer for maintaining the sub-micron gap between the panel and the facing element.

22. The thermophotovoltaic generator of claim 21 in which the actuating spacer includes a piezoelectric element, responsive to a control circuit which selectively applies a voltage to the spacer to control the sub-micron gap.

23. A system for maintaining a microcavity over a macroscale, the system comprising:

a first element;

a second element spaced from the first element;

an array of panels mounted on the second element having surfaces facing the first element defining a sub-micron gap between the panel surfaces and the first element; and

a device associated with each panel which allows each panel to move with respect to the second element to position each panel'"'"'s surface at a spacing from the first element thereby defining a microcavity between the first and second elements.

24. The system of claim 23 in which each panel'"'"'s surface includes protrusions thereon which are engagable with the first element for limiting the spacing between each panel'"'"'s surface and the first element.

25. The system of claim 23 in which the device includes flexural elements connected between at least one panel of the array of panels and the second element for passively maintaining the spacing between each panel'"'"'s surface and the first element.

26. The system of claim 23 in which the device includes an actuator connected between at least one panel of the array of panels and the second element for actively maintaining the spacing between each panel'"'"'s surface and the first element.

27. The system of claim 23 in which the first element is positioned to receive thermal energy.

28. The system of claim 27 in which the second element is connected to a converter for generating electricity in response to thermal energy transferred from the first element to the panel surfaces.

29. The system of claim 23 in which the microcavity is an oscillating cavity and the device includes an actuator for moving each panel to cause oscillations in the cavity.

30. A microelectro mechanical cell comprising a pair of juxtaposed parallel opposing planar surfaces separated by a microgap of spacing, one surface comprising a mosaic of similar planar silicon surfaces each provided with silicon dioxide protrusions at a plurality of points on each silicon surface, the mosaic being mounted against the other surface with said protrusions of each silicon surface contacting the other surface.

31. The microelectro mechanical cell of claim 30 wherein the silicon surfaces are each flexible to control the mounting against said other surface.

32. The microelectro mechanical cell of claim 30 wherein means is provided for maintaining the surfaces at different temperatures.

33. The microelectro mechanical cell of claim 31 wherein a sensor is provided for sensing said spacing, and means is provided responsive to said sensing for varying the spacing through flexing of one or more of the silicon surfaces.

34. A method of constructing a microelectro mechanical cell comprising a planar photovoltic surface juxtaposed with a parallel mosaic of planar silicon surfaces therefrom to define a microgap there between to provide such a microgap of uniform spacing that comprises oxidizing a plurality of marginal points of each silicon surface that is to oppose the photovoltic surface to grow corresponding silicon oxide protrusions from the silicon surfaces;

and juxtaposing the mosaic and photovoltic surfaces with the silicon oxide protrusions of each silicon surface resting on the opposing points of the juxtapose photovoltic surface.

35. The method of claim 34 and in which the opposing silicon surfaces are made compliant to flex upon such juxtaposition.

36. The method of claim 34 wherein said microgap is evacuated.

37. The method of claim 34 where the photovoltaic surface is heated.