Vibration induced perpetual energy resource

• US 20030197448A1
• Filed: 04/17/2002
• Published: 10/23/2003
• Est. Priority Date: 04/17/2002
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Tanielian, Minas H.
• Granted Patent: US 6,771,007 B2
• Time in Patent Office: Days
• US Class Current: 310/328
• CPC Class Codes: H02N 2/186 Vibration harvesters
• CPC Class Codes: H10N 30/01 Manufacture or treatment
• CPC Class Codes: H10N 30/306 Cantilevers
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49149 by metal fusion bonding
• CPC Class Codes: Y10T 29/49798 Dividing sequentially from leading end, e.g., by cutting or breaking

Abstract

A piezoelectric device connected to a vibration source converts vibration energy to electrical current. A plurality of pairs of oppositely polarized piezoelectric wafers deflect to produce an electrical current. Each pair of wafers are arranged back-to-back and electrically joined together. The plurality of pairs of wafers are each connected to a set of micro-machined parts. Each pair of wafers form a bimorph, configured as a cantilevered beam attached to a set of parts to form an element. Each cantilevered beam has a mass weighted first end and is fixedly attached to one or more flexible sheaths on a second end. A plurality of elements form a cell unit. A plurality of cell units form an array. The electrical current produced varies by the number of elements per cell unit, and/or with the number of cell units per array.

Claims

1. A bimorph piezoelectric device comprising:

a plurality of micro-electro-mechanical-system (MEMS) piezoelectric beams, said plurality of MEMS beams arranged as pairs of MEMS beams, each pair having a connecting end and a weighted end;

each of said pairs of MEMS beams being electrically and mechanically joined through its connecting end to at least one flexible sheath having a plurality of electrically conductive traces to form a joined array of MEMS beams each having its weighted end free to deflect; and

each weighted end of said pairs of MEMS beams of said joined array being deflectable to produce an electric current proportional to a quantity of said pairs of MEMS beams, said electric current collectable from each of said at least one flexible sheath.

2. The device of claim 1, wherein each of said plurality of MEMS piezoelectric beams comprises a layer of piezoelectric material sandwiched between adjoining layers of electrically conductive material.

3. The device of claim 3, wherein each pair of MEMS beams is formed by joining an inner adjoining electrically conductive layer of one beam of each beam pair to an inner adjoining electrically conductive layer of an alternate beam of each beam pair.

4. The device of claim 3, wherein each said weighted end has a weighted mass attached to each of an opposed pair of outer layers of electrically conductive material of each beam pair.

5. The device of claim 4, further comprising:

said at least one flexible sheath being an upper sheath and a lower sheath;

an upper intermediate beam connecting a first of said opposed pairs of outer layers of electrically conductive material to said upper sheath;

a lower intermediate beam connecting a second of said opposed pairs of outer layers of electrically conductive material to said lower sheath.

6. The device of claim 5, wherein both said upper intermediate beam and said lower intermediate beam are joined to each said flexible sheath by an electrically conductive adhesive.

7. The device of claim 5, wherein each said flexible sheath provides a deflection limit for each adjacent weighted mass to prevent fracture of said piezoelectric material of each pair of MEMS beams by over-deflection of said piezoelectric material.

8. The device of claim 7 wherein each said flexible sheath further comprises a plurality of perforations providing for flow of an etching solution.

9. The device of claim 3 further wherein each pair of MEMS beams is connected at its connecting end to a single flexible sheath forming a vertical array of MEMS beams.

10. The device of claim 9 wherein said weighted end of both MEMS beams forming each pair of MEMS beams form a pair of weighted ends having a single mass attached thereto.

11. A piezoelectric device for converting vibration energy to electric current comprising:

a plurality of pairs of oppositely polarized piezoelectric layers deflectable to produce an electrical current;

said plurality of pairs of layers each connected to a set of micro-machined elements;

each said set of elements with said pairs of layers forming a bimorph, said bimorph configured as a cantilevered beam;

each said cantilevered beam being mass weighted on a first beam end and fixedly attached to at least one protective sheath on a second beam end; and

a plurality of said bimorphs on said at least one protective sheath forming an array.

12. The device of claim 11, further comprising:

each said protective sheath having a bimorph attachment side and a vibration body attachment side; and

said bimorph attachment side collects said electrical current from each bimorph attached thereto for one of extraction, storage, and distribution of said electrical current.

13. The device of claim 12, wherein said vibration body attachment side is rigidly fixed to a vibration source to produce an oscillating deflection of each bimorph to generate said electrical current.

14. The device of claim 13, wherein a quantity of said bimorphs within said array varies in direct proportion to a value of said electrical current.

15. The device of claim 11, wherein said plurality of micro-machined refractory metal elements is selected from the group consisting of tungsten, molybdenum, tantalum, and titanium.

16. The device of claim 11, further comprising:

said array forms a first layer of a multilayer piezoelectric power generator; and

each layer of said power generator is a copy of said array.

17. A method for forming a horizontally configured piezoelectric electrical current generating device which comprises the steps of:

creating an initial sub-assembly by;

joining paired piezoelectric material plates to an upper surface of a micromachining a lower surface of said substrate to both form a plurality of masses supported by said piezoelectric material plates and retain a plurality of non-machined lower surface areas;

electrically bonding said plurality of non-machined lower surface areas to a protective sheath having electrical traces; and

cutting through said piezoelectric material to separate a plurality of individual cantilevered piezoelectric material beam lengths; and

constructing a mirror-image sub-assembly to said initial sub-assembly; and

connecting said mirror image sub-assembly to said initial sub-assembly.

18. The method of claim 17, further comprising the step of preparing a mirror image sub-assembly to said initial sub-assembly by the steps of claim 17.

19. The method of claim 18, further comprising the steps of:

aligning each of said plurality of individual cantilevered piezoelectric material beam lengths of said mirror image sub-assembly with selected ones of said plurality of individual cantilevered piezoelectric material beam lengths of said initial sub-assembly; and

connecting each aligned plurality of individual cantilevered piezoelectric material beam lengths to form a plurality of bimorph beams.

20. The method of claim 19, further comprising the steps of:

forming a pattern of trenches using photolithography and etching on said upper surface of said substrate prior to joining said paired piezoelectric material plates; and

filling said trenches with a sacrificial material.

21. The method of claim 20, further comprising the step of depositing a metallization film over said upper surface of said substrate and said sacrificial material after filling said trenches with said sacrificial material and prior to joining said paired piezoelectric material plates.

22. The method of claim 21, further comprising the step of removing a pattern of trenches using photolithography and etching from a lower surface of said substrate after joining said paired piezoelectric material plates.

23. The method of claim 22, further comprising the step of etching to remove a remaining portion of said sacrificial material after culling through said piezoelectric material.

24. A method for forming a vertically configured piezoelectric electrical current generating device which comprises the steps of:

filling until dry a sacrificial plastic replica mold with a ceramic piezoelectric slurry to form a piezoceramic green body;

bonding a piezoceramic wafer to said piezoceramic green body;

heat curing said piezoceramic wafer and piezoceramic green body to both remove said plastic mold and expose a plurality of piezoceramic vertical beams;

casting a resist over said beams along a top surface thereof;

aligning an X-ray exposure to create a plurality of recesses for an electrode structure;

flood exposing a remaining portion of said vertical beams;

spin-coating a metal filled, negative X-ray resist on said top surface to provide a cantilevered mass; and

stripping both a remaining portion of said negative resist and said flood exposed resist to form a plurality of said cantilevered piezoceramic vertical beams each having one of a plurality of cantilevered masses.

25. The method of claim 24, further comprising the step of fabricating a mold insert to prepare at least one of said sacrificial replica molds.

26. The method of claim 25, further comprising the step of fabricating said mold insert using a lithographie galvanic abformung (LIGA) machining process.

27. The method of claim 28, further comprising the step of fabricating said mold insert from a nickel material.

28. The method of claim 24, further comprising the steps of:

polishing an exposed surface of said dried piezoceramic green body prior to bonding said wafer to said piezoceramic green body; and

depositing a metal conductive layer through a mask onto said polished surface to form a plurality of electrical contacts to said piezoceramic vertical beams.

29. The method of claim 24, further comprising the step of plating said recesses with a nickel material prior to flood exposure.

30. The method of claim 24, further comprising the step of planarizing said top surface prior to casting said resist over said beams.

31. The method of claim 24, further comprising the step of developing said remaining portion of said negative resist and said flood exposed resist.