MEMS BASED PYROELECTRIC THERMAL ENERGY HARVESTER
First Claim
1. A pyroelectric thermal energy harvesting apparatus for generating an electric current comprising:
- a first surface having a first temperature (TH);
a second surface spaced apart from the first surface, the second surface having a second temperature (TL) that is less the first temperature (TH) resulting in a temperature difference between the first surface and the second surface;
a layered capacitor disposed between the first surface and the second surface, the capacitor having,a conductive, bimetal top electrode layer cantilevered from one of the first surface and the second surface by an anchor,a conductive bottom electrode layer facing the second surface,a pyroelectric dielectric layer sandwiched between the top and bottom electrodes;
a pair of proof masses, one proof mass affixed to each electrode layer and each facing one of the first surface and the second surface; and
wherein the temperature difference between the first surface and the second surface causes the layered capacitor to deform by differential thermal expansion between the top electrode layer and the dielectric layer, causing the proof masses to alternately contact the first and second surfaces at the resonant frequency of the layered capacitor such that a pyroelectric current is generated between the electrodes.
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Abstract
A pyroelectric thermal energy harvesting apparatus for generating an electric current includes a cantilevered layered pyroelectric capacitor extending between a first surface and a second surface, where the first surface includes a temperature difference from the second surface. The layered pyroelectric capacitor includes a conductive, bimetal top electrode layer, an intermediate pyroelectric dielectric layer and a conductive bottom electrode layer. In addition, a pair of proof masses is affixed at a distal end of the layered pyroelectric capacitor to face the first surface and the second surface, wherein the proof masses oscillate between the first surface and the second surface such that a pyroelectric current is generated in the pyroelectric capacitor due to temperature cycling when the proof masses alternately contact the first surface and the second surface.
41 Citations
24 Claims
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1. A pyroelectric thermal energy harvesting apparatus for generating an electric current comprising:
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a first surface having a first temperature (TH); a second surface spaced apart from the first surface, the second surface having a second temperature (TL) that is less the first temperature (TH) resulting in a temperature difference between the first surface and the second surface; a layered capacitor disposed between the first surface and the second surface, the capacitor having, a conductive, bimetal top electrode layer cantilevered from one of the first surface and the second surface by an anchor, a conductive bottom electrode layer facing the second surface, a pyroelectric dielectric layer sandwiched between the top and bottom electrodes; a pair of proof masses, one proof mass affixed to each electrode layer and each facing one of the first surface and the second surface; and wherein the temperature difference between the first surface and the second surface causes the layered capacitor to deform by differential thermal expansion between the top electrode layer and the dielectric layer, causing the proof masses to alternately contact the first and second surfaces at the resonant frequency of the layered capacitor such that a pyroelectric current is generated between the electrodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A pyroelectric thermal energy harvesting apparatus for generating an electric current comprising:
an elongated, layered capacitor extending between a first surface and a second surface, the first surface having a temperature difference from the second surface, the layered capacitor having a proximal end anchored to the first surface and an opposite distal end, the layered capacitor including a conductive, bimetal top electrode layer, an intermediate pyroelectric dielectric layer and a conductive bottom electrode layer, wherein the layered capacitor oscillates between and makes contact with the first surface and the second surface such that a temperature change is induced in the layered capacitor thereby generating a current when the layered capacitor is connected to an external circuit. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of generating an electric current from a pyroelectric thermal energy harvesting apparatus comprising the steps of:
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a) providing a thermal energy source including, a first surface having a first temperature (TH), a second surface having a second temperature (TL) that is less than the first temperature (TH), the second surface being spaced apart from the first surface, a layered capacitor disposed between the first surface and the second surface, the capacitor having, a conductive, bimetal top electrode layer cantilevered from the first surface by an anchor, a conductive bottom electrode layer facing the second surface, a pyroelectric dielectric layer sandwiched between the top and bottom electrodes, a pair of proof masses, one proof mass affixed to each electrode layer and each facing one of the first surface and the second surface; b) alternately deforming the bimetal top electrode with the temperature gradient between the first temperature (TH) and the second temperature (TL), such that the proof masses alternately contact the first surface and the second surface at the resonant frequency of the layered capacitor; and c) placing an electric load between the top electrode and the bottom electrode. - View Dependent Claims (21, 22, 23, 24)
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Specification