Shape memory alloy MEMS heat engine
First Claim
1. An oscillating shape memory alloy heat engine comprising;
- an oscillating memberwherein said member has a dimension less than 100 micronswherein a first portion of said member comprises a shape memory alloya heat sourcea cold sourcewherein said heat engine has a temperature gradient between said heat source and said cold source,wherein said temperature gradient is the difference between said heat source and said cold source,wherein said temperature gradient has a heat flow,wherein a portion of said heat flow is converted into mechanical power,wherein said mechanical power portion is a fraction of said heat flow,wherein said mechanical power fraction is proportional to said difference between said heat source and said cold source,wherein said heat engine contains an isolation region,wherein said isolation region reduces said heat flow into said cold sourcewherein said oscillating member contains at least one thin filmwherein said heat source has a distance from said oscillating member,wherein said distance from said oscillating member oscillates when said oscillating member oscillates,wherein said oscillating member has at least a first and a second position,wherein said heat source has a heat source temperature above an austenite transformation temperature for said shape memory alloy,wherein said cold source has a cold source temperature below a martensite transformation temperature for said shape memory alloy,wherein said heat source temperature is capable of transforming the phase of a portion of the shape memory alloy of the oscillating member when in said first position from martensite to austenite thus changing the oscillating member position from said first position to said second position,wherein said cold source temperature is capable of transforming the phase of a portion of the shape memory alloy of the oscillating member when in said second position from austenite to martensite thus changing the oscillating member position from said second position to said first position,wherein said cold source transforming the phase occurs when said heat source is at said heat source temperature,wherein said oscillating member contains a means for converting mechanical energy into electrical energy.
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Abstract
A microelectromechanical systems (MEMS) based heat engine capable of converting thermal energy gradients into mechanical or electrical energy, as well as its fabrication process is disclosed. This heat engine design consists of a stressed oscillating beam formed from a shape memory alloy (SMA) thin film. As the temperature of the beam changes, its shape changes due to the phase transformation of the shape memory alloy, causing it to oscillate between a hot source and a cold source. Due to the hysteretic behavior of the phase transformation, the oscillating SMA cantilever beam produces a net mechanical work output that may be either converted to electrical energy or mechanically linked to other MEMS devices.
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Citations
16 Claims
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1. An oscillating shape memory alloy heat engine comprising;
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an oscillating member wherein said member has a dimension less than 100 microns wherein a first portion of said member comprises a shape memory alloy a heat source a cold source wherein said heat engine has a temperature gradient between said heat source and said cold source, wherein said temperature gradient is the difference between said heat source and said cold source, wherein said temperature gradient has a heat flow, wherein a portion of said heat flow is converted into mechanical power, wherein said mechanical power portion is a fraction of said heat flow, wherein said mechanical power fraction is proportional to said difference between said heat source and said cold source, wherein said heat engine contains an isolation region, wherein said isolation region reduces said heat flow into said cold source wherein said oscillating member contains at least one thin film wherein said heat source has a distance from said oscillating member, wherein said distance from said oscillating member oscillates when said oscillating member oscillates, wherein said oscillating member has at least a first and a second position, wherein said heat source has a heat source temperature above an austenite transformation temperature for said shape memory alloy, wherein said cold source has a cold source temperature below a martensite transformation temperature for said shape memory alloy, wherein said heat source temperature is capable of transforming the phase of a portion of the shape memory alloy of the oscillating member when in said first position from martensite to austenite thus changing the oscillating member position from said first position to said second position, wherein said cold source temperature is capable of transforming the phase of a portion of the shape memory alloy of the oscillating member when in said second position from austenite to martensite thus changing the oscillating member position from said second position to said first position, wherein said cold source transforming the phase occurs when said heat source is at said heat source temperature, wherein said oscillating member contains a means for converting mechanical energy into electrical energy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 16)
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13. A method of producing self assembled devices comprising;
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depositing a first layer on a substrate; depositing a second layer thus forming a shape; wherein said first and second layers have different thermal expansion coefficients; changing temperature of the layers by at least 10 degrees centigrade; wherein said changing of the temperature changes the shape, wherein said shape has a dimension less than 100 microns, wherein said self assembled device is a heat engine by adding, a heat source and a cold source, wherein said heat engine has a temperature gradient between said heat source and said cold source, wherein said temperature gradient is the difference between said heat source and said cold source, wherein said temperature gradient has a heat flow, wherein a portion of said heat flow is converted into mechanical power, wherein said mechanical power portion is a fraction of said heat flow, wherein said mechanical power fraction is proportional to said difference between said heat source and said cold source, wherein said heat engine contains an isolation region, wherein said isolation region reduces said heat flow into said cold source, wherein an oscillating member has at least a first and a second position, wherein said heat source has a distance from said oscillating member, wherein said distance from said oscillating member oscillates when said oscillating member oscillates wherein said heat source has a heat source temperature above the austenite transformation temperature, wherein said cold source has a cold source temperature below the martensite transformation temperature, wherein said heat source temperature is capable of transforming the phase of a portion of the shape memory alloy of the oscillating member when in said first position from martensite to austenite thus changing the oscillating member position from said first position to said second position, wherein said cold source temperature is capable of transforming the phase of a portion of the shape memory alloy of the oscillating member when in said second position from austenite to martensite thus changing the oscillating member position from said second position to said first position, wherein said cold source transforming the phase occurs when said heat source is at said heat source temperature, said heat engine having means for converting mechanical energy into electrical energy.
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14. The method as claimed in claim l3;
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wherein said shape change causes contact with and moves a second device, wherein said second device is a micromirror.
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Specification