Multi-layer micro-energy harvester and method of making the same

• US 20100301699A1
• Filed: 05/28/2009
• Published: 12/02/2010
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: Gang Zhang
• Original Assignee: Gang Zhang
• Inventors: Zhang, Gang
• Granted Patent: US 8,410,658 B2
• Time in Patent Office: Days
• US Class Current: 310/300
• 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: H02N 1/08 with conductive charge carrier, i.e. capacitor machines

Abstract

The embodiments of the present invention are directed to multi-layer electrostatic energy harvester structures for extracting and converting more ambient vibration energy into electrical energy and/or extracting ambient vibration energy at a plurality of different vibration frequencies or frequency ranges. In some embodiments, a multi-layer electrostatic energy harvester structure comprises a plurality of bonded variable capacitor layers. In some embodiments, a multi-layer electrostatic energy harvester structure comprises a plurality of variable capacitor layers and at least one moving mass layer that are bonded together. Still in some embodiments, a multi-layer electrostatic energy harvester structure comprises a plurality of separate variable capacitor layers. One preferred multi-layer microfabrication method is provided to make multi-layer electrostatic energy harvester structures disclosed in the present invention, comprising: forming a plurality of separate layers that compose a multi-layer electrostatic energy harvester structure wherein each of the plurality of separate layers comprises at least one material and wherein at least one of the plurality of separate layers comprises a sacrificial material; bonding at least the plurality of separate layers together; and removing at least a portion of the sacrificial material.

Claims

1. A multi-layer structure that is at least a portion of an electrostatic energy harvester for extracting and converting ambient vibration energy into electrical energy, comprising:

(a) a plurality of variable capacitor layers, each of which comprises at least one fixed electrode, one movable electrode, and at least one spring structure that supports the movable electrode wherein the at least one fixed electrode forms at least one variable capacitor with the movable electrode,

wherein the plurality of variable capacitor layers are bonded together as desired to form at least one multi-layer variable capacitor comprising at least one multi-layer fixed electrode, one multi-layer movable electrode, and at least one multi-layer spring structure.

2. The structure of claim 1, further comprising:

(a) a substrate; and

(b) a plurality of separate anchor components which are secured to the substrate,

wherein the at least one multi-layer variable capacitor is anchored to the substrate by bonding the at least one multi-layer fixed electrode and the at least one multi-layer spring structure to the plurality of anchor components as desired, and

wherein the multi-layer movable electrode is suspended above the substrate by the at least one multi-layer spring structure.

3. The structure of claim 1 wherein on each of the plurality of variable capacitor layers the at least one fixed electrode and the movable electrode comprise a plurality of comb fingers wherein the comb fingers of the at least one fixed electrode are arranged to be interdigitated with the comb fingers of the movable electrode to form at least one variable comb capacitor.

4. The structure of claim 1 wherein each of the variable capacitor layers comprises at least a material of silicon.

5. The structure of claim 2 wherein material of the plurality of anchor components is silicon and material of the substrate is glass or silicon comprising a layer of silicon dioxide on at least one silicon surface to which the plurality of anchor components are secured, wherein material of the plurality of anchor components is silicon oxide and material of the substrate is silicon, or wherein materials of the plurality of anchor components and the substrate are glass.

6. The structure of claim 3 wherein the at least one variable comb capacitor is an in-plane constant gap comb capacitor or an in-plane gap closing comb capacitor.

7. A multi-layer structure that is at least a portion of an electrostatic energy harvester for extracting and converting ambient vibration energy into electrical energy, comprising:

(a) at least two variable capacitor layers, each of which comprises at least one fixed electrode, one movable electrode, and at least one spring structure that supports the movable electrode wherein the at least one fixed electrode forms at least one variable capacitor with the movable electrode; and

(b) at least one moving mass layer, each of which comprises at least one moving mass component and a plurality of separate connection components,

wherein the at least two variable capacitor layers and the at least one moving mass layer are bonded together as desired to form at least one multi-layer variable capacitor comprising at least one multi-layer fixed electrode, one multi-layer movable electrode, and at least one multi-layer spring structure,

wherein all of the connection components are a portion of the at least one multi-layer fixed electrode and the at least one multi-layer spring structure wherein each of the at least one multi-layer fixed electrode and the at least one multi-layer spring structure comprises at least one connection component,

wherein all of the moving mass components are a portion of the multi-layer movable electrode, and

wherein two outermost layers of the bonded layers are two variable capacitor layers.

8. The structure of claim 7, further comprising:

(a) a substrate; and

(b) a plurality of separate anchor components which are secured to the substrate,

wherein the at least one multi-layer variable capacitor is anchored to the substrate by bonding the at least one multi-layer fixed electrode and the at least one multi-layer spring structure to the plurality of anchor components as desired, and

wherein the multi-layer movable electrode is suspended above the substrate by the at least one multi-layer spring structure.

9. The structure of claim 7 wherein on each of the at least two variable capacitor layers the at least one fixed electrode and the movable electrode comprise a plurality of comb fingers wherein the comb fingers of the at least one fixed electrode are arranged to be interdigitated with the comb fingers of the movable electrode to form at least one variable comb capacitor.

10. The structure of claim 7 wherein each of the bonded layers comprises at least a material of silicon.

11. The structure of claim 7 wherein at least one of the moving mass components comprises at least one closed silicon frame inside which there is at least one filled material wherein the at least one filled material has a higher density than that of silicon.

12. The structure of claim 11 wherein one of the at least one filled material is silver or gold.

13. The structure of claim 12 wherein the silver or gold is formed by filing and firing at least silver or gold particles.

14. The structure of claim 8 wherein material of the plurality of anchor components is silicon and material of the substrate is glass or silicon comprising a layer of silicon oxide on at least one silicon surface to which the plurality of anchor components are secured, wherein material of the plurality of anchor components is silicon dioxide and material of the substrate is silicon, or wherein materials of the plurality of anchor components and the substrate are glass.

15. The structure of claim 9 wherein the at least one variable comb capacitor is an in-plane constant gap comb capacitor or an in-plane gap closing comb capacitor.

16. A multi-layer structure that is at least a portion of an electrostatic energy harvester for extracting and converting ambient vibration energy into electrical energy, comprising:

(a) a substrate; and

(b) a plurality of separate variable capacitor layers, each of which comprises at least one fixed electrode, one movable electrode, and at least one spring structure that supports the movable electrode, wherein the at least one fixed electrode forms at least one variable capacitor with the movable electrode,

wherein the plurality of variable capacitor layers are respectively anchored to the substrate and located in different height planes above the substrate by bonding the at least one fixed electrode and the at least one spring structure of each variable capacitor layer to a plurality of separate anchor components as desired wherein the plurality of anchor components are secured to the substrate, and

wherein the movable electrode of each of the plurality of variable capacitor layers is suspended above the substrate by the at least one spring structure of the same layer.

17. The structure of claim 16 wherein on each of the plurality of separate variable capacitor layers the at least one fixed electrode and the movable electrode comprise a plurality of comb fingers wherein the comb fingers of the at least one fixed electrode are arranged to be interdigitated with the comb fingers of the movable electrode to form at least one variable comb capacitor.

18. The structure of claim 16 wherein each of the plurality of separate variable capacitor layers comprises at least a material of silicon.

19. The structure of claim 16 wherein material of all of the anchor components is silicon and material of the substrate is glass or silicon comprising a layer of silicon dioxide on at least one silicon surface to which all of the anchor components are secured.

20. The structure of claim 17 wherein the at least one variable comb capacitor is an in-plane constant gap comb capacitor or an in-plane gap closing comb capacitor.