Bimorphic, compositionally-graded, sputter-deposited, thin film shape memory device
OwnerKen K. Ho, Gregory P. Carman +1inventors
InventorsKen K. Ho, Gregory P. Carman, Peter A. Jardine
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Abstract
The present invention discloses devices and a method of fabrication of devices using a shape memory effect, thin film with a compositional gradient through the thickness of the film. Specifically, a NiTi SME thin film is disclosed that can be used in actuators, MEMS devices and flow control. The process of fabrication includes a gradual heating of the target over time during the sputter deposition of a thin film on a substrate under high vacuum, without compositional modification. The resulting thin film exhibits two-way shape memory effect that can be cyclically applied without an external bias force.
Claims13
A sputter deposition process for fabricating a shape memory alloy thin film, comprising:
- inserting a target comprised of nickel and titanium and a substrate in an ultra high vacuum, sputter deposition chamber;
- drawing an ultra high vacuum in the system, wherein the partial pressures of reactive vapors are less than a maximum pressure, wherein the maximum pressure is determined by the pressure at which the reaction between the reactive vapors and one or more of the constituent elements is negligible;
- controlling the initial temperature of the target;
- exposing the substrate;
- depositing material from the target to the substrate, wherein the temperature of the target is changed over time during deposition of the shape memory alloy thin film.
A sputter-deposited, thin film shape memory effect device comprising:
- a SME thin film comprised of nickel and titanium, wherein the thin film is sputter-deposited and the thin film has a compositional gradation through at least a portion of the thickness of the thin film, and the compositional gradation is selected such that a phase change occurs above room temperature, wherein the phase change is capable of activating a two-way shape memory effect.
A microscale actuator for active flow control, comprising:
- a SME thin film comprised of nickel and titanium, wherein the thin film is sputter-deposited, and the thin film comprises a bubble membrane, and the thin film has a compositional gradation through at least a portion of the thickness of the thin film, and the compositional gradation is selected such that a phase change occurs above room temperature, wherein the phase change is capable of activating a two-way shape memory effect in the bubble membrane.
A microscale actuator comprising:
- a SME thin film comprised of nickel and titanium, wherein the thin film is sputter-deposited, wherein the thin film comprises at least one linear element, and wherein the thin film has a compositional gradation through at least a portion of the thickness of the thin film, and wherein the compositional gradation is selected such that a phase change occurs above room temperature, wherein the phase change is capable of activating a two-way shape memory effect in the at least one a linear element.
A sputter deposition process for fabricating a thin film shape memory effect device, comprising:
- inserting a Ni:Ti target and a substrate in an ultra high vacuum, sputter deposition chamber;
- drawing an ultra high vacuum in the system, wherein the partial pressures of water, carbon dioxide and carbon monoxide are less than about 10−8 Torr;
- controlling the temperature of the target;
- exposing the substrate;
- depositing material from the Ni:Ti target to the substrate, wherein the temperature of the target is gradually increased over time.
A sputter-deposited, thin film shape memory effect device, comprising a thin film of NiTi material, wherein the thin film of NiTi material is sputter deposited and wherein the thin film of NiTi has a compositional gradation through the thickness of the film, and wherein the compositional gradation is selected such that a phase change occurs above room temperature that activates a two-way shape memory effect.
Dependencies are inferred from the claim text.