Abstract: Thermally activated devices, including thermally activated release devices. These devices may be used as part of any device or system in which thermal activation may be desired. In particular, described herein are thermally activated devices configured as sprinkler valves. The thermally activated devices typically include a channel and a plug element, where the plug element is a shape memory material, which may be a single-crystal shape memory alloy. The channel has two connected regions, where the first region has a diameter that is greater than the diameter of a plug element in a first configuration and the second region has a diameter that is less than the diameter of the plug element in the first configuration but greater than the diameter of the plug element in its second configuration.

Abstract: A temperature-activated valve for a conventional fire sprinkler utilizing a hyperelastic single-crystal shape memory alloy is described. The shape-memory element expands as it is heated, forcing a bolt to break, thereby opening the sprinkler valve. The devices described are less susceptible to accidental breakage than conventional actuators, and have fewer moving parts. Transition temperature of the shape memory alloy can be tuned to a narrow range.

Abstract: A temperature-activated valve for a conventional fire sprinkler utilizing a hyperelastic single-crystal shape memory alloy is described. The shape-memory element expands as it is heated, forcing a bolt to break, thereby opening the sprinkler valve. The shape memory element typically communicates with the valve so as to force it open. The devices described are less susceptible to accidental breakage than conventional actuators, and have fewer moving parts. Transition temperature of the shape memory alloy can be tuned to a narrow range.

Abstract: Metal seeds for forming single-crystal shape-memory alloys (SMAs) may be fabricated with high reliability and control by alloying thin films of material together. In particular, described herein are methods of forming AlCuNi SMAs by first producing high-quality seeds (ingots) of copper, aluminum, and nickel to produce for pulling single crystal shape memory alloys, in particular superelastic or hyperelastic alloys. The method is applicable to a wide range of alloys in which one or more of the components are reactive. The method is an improvement upon traditional methods such as mixing and melting pellets. In this improved method, a reactive layer (e.g., aluminum) is provided in thin flat layers between layers of other materials (e.g., copper and layers of nickel).

Abstract: Described herein are devices and methods fabricating devices having nanostructures that allow adhesion or growth of one cell type, such as endothelial cells, more than another cell type, such as smooth muscle cells. In particular, stent covers having such nanostructures are described, and methods for fabricating these stent covers. Also described herein are methods for optimizing the nanostructures forming the devices.

Abstract: A thin film device, such as an intravascular stent, is disclosed. The device is formed of a seamless expanse of thin-film (i) formed of a sputtered nitinol shape memory alloy, defining, in an austenitic state, an open, interior volume, having a thickness between 0 5-50 microns, having an austenite finish temperature Af below 37° C.; and demonstrating a stress/strain recovery greater than 3% at 37° C. The expanse can be deformed into a substantially compacted configuration in a martensitic state, and assumes, in its austenitic state, a shape defining such open, interior volume. Also disclosed is a sputtering method for forming the device.

Abstract: Shape-setting methods for fabricating devices made of single crystal shape memory alloys. The method include drawing a single crystal of a shape memory alloy from a melt of the alloy. This is followed by heating and quenching the crystal sufficiently rapid to limit the formation of alloy precipitates to an amount which retains hyperelastic composition and properties of the crystal.

Abstract: A thin film device and fabrication method providing optimum tear resistance. A thin film layer is formed with a first and second of rows of holes. The holes in each row are spaced-apart along an axis which extends along an edge of the layer. The holes in one row are in overlapping relationship with adjacent holes in the other row. The holes have a diameter which is sufficiently large so that an imaginary line extending perpendicular from any location along the edge will intersect at least one hole, thus preventing further propagation of any tears or cracks which start from the edge.

Abstract: Devices and methods of making devices having one or more components made of single crystal shape memory alloy capable of large recoverable distortions, defined herein as “hyperelastic” SMA. Recoverable Strains are as large as 9 percent, and in special circumstances as large as 22 percent. Hyperelastic SMAs exhibit no creep or gradual change during repeated cycling because there are no crystal boundaries. Hyperelastic properties are inherent in the single crystal as formed: no cold work or special heat treatment is necessary. Alloy components are Cu—Al—X where X may be Ni, Fe, Co, Mn. Single crystals are pulled from melt as in the Stepanov method and quenched by rapid cooling to prevent selective precipitation of individual elemental components. Conventional methods of finishing are used: milling, turning, electro-discharge machining, abrasion. Fields of application include aerospace, military, automotive, medical devices, microelectronics, and consumer products.

Abstract: A magnetic data storage system having a scanning tip array based system and a shape memory thin film-based data storage medium. Prior to storing data, the medium is in its non-ferromagnetic austenitic phase. Indentation stress locally induces martensitic transformation of the medium, which in turn generates a locally ferromagnetized surface. By measuring the magnetic force interaction between the tip and the medium surface, inscribed magnetic information can be read. The shape memory thin film enables the stress-induced local magnetic transition to provide a fast data storage system with high data storage density.

Abstract: Devices and methods of making devices having one or more components made of single crystal shape memory alloy capable of large recoverable distortions, defined herein as “hyperelastic” SMA. Recoverable Strains are as large as 9 percent, and in special circumstances as large as 22 percent. Hyperelastic SMAs exhibit no creep or gradual change during repeated cycling because there are no crystal boundaries. Hyperelastic properties are inherent in the single crystal as formed: no cold work or special heat treatment is necessary. Alloy components are Cu—Al—X where X may be Ni, Fe, Co, Mn. Single crystals are pulled from melt as in the Stepanov method and quenched by rapid cooling to prevent selective precipitation of individual elemental components. Conventional methods of finishing are used: milling, turning, electro-discharge machining, abrasion. Fields of application include aerospace, military, automotive, medical devices, microelectronics, and consumer products.

Abstract: Shape-setting methods for fabricating devices made of single crystal shape memory alloys. The method include drawing a single crystal of a shape memory alloy from a melt of the alloy. This is followed by heating and quenching the crystal sufficiently rapid to limit the formation of alloy precipitates to an amount which retains hyperelastic composition and properties of the crystal.

Abstract: A method of forming a single crystal in a thin film by progressively rapidly heating (and cooling) a narrow band of amorphous material. The amorphous thin film may be of shape memory alloy such as TiNi or CuAlNi. Heating may be accomplished by a line-focused laser beam. The thin film may be formed by sputter deposition on a substrate such as silicon. The thin film crystal that is formed has non-isotropic stress/strain characteristics, and very large recoverable strain in a preferred direction. The single crystal SMA exhibits greater strain recovery; Constant force deflection; Wider transition temperature range; Very narrow loading hysteresis; and Recovery that is repeatable & complete. Single Crystal SMA is manufactured by pulling a single crystal from melt, a method similar to that used by the semiconductor industry to fabricate silicon boules. This process enables manufacture of materials that approach theoretical limits.

Abstract: A temperature-activated valve for a conventional fire sprinkler utilizing a hyperelastic single-crystal shape memory alloy is described. The shape-memory element expands as it is heated, forcing a bolt to break, thereby opening the sprinkler valve. The devices described are less susceptible to accidental breakage than conventional actuators, and have fewer moving parts. Transition temperature of the shape memory alloy can be tuned to a narrow range.

Abstract: Eyeglass frame hinges are replaced by flexures made of hyperelastic single-crystal shape memory alloy. These flexures exhibit more than 8 percent recoverable strain. Eyeglass frames with these flexures can be distorted repeatedly in ways that would destroy ordinary hinges, and recover without damage. Flexures may be incorporated in eyeglass frames in ways that make them attractive as fashion items, thus enhancing the value of a commodity consumer product.

Abstract: A device and method for holding or clamping components together, and with the clamping being selectively loosened to permit the components to move through a predetermined distance without being fully released. A bolt has its head end attached to one component and its threaded end attached to the other component. A portion of the bolt's shank is formed with a necked-down portion. An actuator of shape memory alloy material is mounted about the bolt. When energized by heat, the actuator expands and exerts a great force which stretches the bolt, permanently deforming the bolt. This enables limited movement of the components while still restraining them from separating.

Abstract: Described herein are fasteners and devices for securing together several components so that the load applied to the components is constant or nearly constant. The fasteners described herein include a hyperelastic member having first end to which a first retainer is coupled and a second end to which a second retainer is coupled. The retainers are configured to contact the structures being fastened and transfer the load from the structures to the hyperelastic member. The hyperelastic member may be an elongate shaft (e.g., a rod, cylinder, strut, etc.), and is a shape memory alloy that is typically fabricated as a single crystal.

Abstract: A microrelay device formed on a silicon substrate wafer for use in opening and closing a current path in a circuit. A pair of electrically conducting latching beams are attached at their proximal ends to terminals on the substrate. Proximal ends of the beams have complementary shapes which releasably fit together to latch the beams and close the circuit. A pair of shape memory alloy actuators are selectively operated to change shapes which bend one of the beams in a direction which latches the distal ends, or bend the other beam to release the distal ends and open the circuit. The microrelay is bistable in its two positions, and power to the actuators is applied only for switching it open or closed.

Abstract: Contraceptive intrauterine devices made of thin film shape memory alloy materials. The devices are formed in three-dimensional shapes which contact uterus tissue of a human or other mammal to prevent conception. In certain embodiments, structural features such as tails, fenestrations, ridges or grooves are formed on the devices to enhance the contraceptive effect.

Abstract: A zinc-air battery and control valve for controlling air flow to energize the battery. Telescoping inner and outer valve sleeves each have a plurality of openings that when aligned communicate air from the exterior to the interior of the valve. Two actuators are provided, one to open the valve and the other to close it. All of the openings are opened or closed simultaneously by sliding motion of the valve sleeves that fit concentrically together. A bistable latching mechanism is provided to keep the valve in either of its two positions. A pair of switches operate in coordination with the latching mechanism so that a closed circuit is established for changing the state from that which was last established.