Abstract: Methods are provided for shape-setting hyperelastic, single-crystal shape memory alloy (SMA) material while preserving the hyperelastic properties of the material. A wire or rod of a single crystal shape memory alloy material is heated to an annealing temperature (Ta). While maintained at the annealing temperature, the wire or rod is shaped by driving the wire or rod and a shaping form together into contact with each other, and the shaped wire or rod is quenched in a quenching medium virtually simultaneously with the shaping.

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: Described herein are methods, systems, and apparatus for shape-setting hyperelastic, single-crystal shape memory alloy (SMA) material while preserving the hyperelastic properties of the material. Also described are hyperelastic, single-crystal SMA devices that have been shape set by these methods. In particular, described herein are hyperelastic, single crystal SMA dental archwires and methods of forming them while preserving the hyperelastic properties, e.g., without significant grain boundaries in the crystal structure.

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 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: We describe herein biocompatible single crystal Cu-based shape memory alloys (SMAs). In particular, we show biocompatibility based on MEM elution cell cytotoxicity, ISO intramuscular implant, and hemo-compatibility tests producing negative cytotoxic results. This biocompatibility may be attributed to the formation of a durable oxide surface layer analogous to the titanium oxide layer that inhibits body fluid reaction to titanium nickel alloys, and/or the non-existence of crystal domain boundaries may inhibit corrosive chemical attack. Methods for controlling the formation of the protective aluminum oxide layer are also described, as are devices including such biocompatible single crystal copper-based SMAs.

Abstract: Shape-setting methods for fabricating devices made of single crystal shape memory alloys. In particular the methods described may be used to fabricate dental arches of single-crystal shape memory alloys. The methods include drawing a single crystal of a shape memory alloy from a melt of the alloy. This is followed by heating, forming, 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: 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: 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 methods, systems, and apparatus for shape-setting hyperelastic, single-crystal shape memory alloy (SMA) material while preserving the hyperelastic properties of the material. Also described are hyperelastic, single-crystal SMA devices that have been shape set by these methods. In particular, described herein are hyperelastic, single crystal SMA dental archwires and methods of forming them while preserving the hyperelastic properties, e.g., without significant grain boundaries in the crystal structure.

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: 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: Shape-setting methods for fabricating devices made of single crystal shape memory alloys. In particular the methods described may be used to fabricate dental arches of single-crystal shape memory alloys. The methods include drawing a single crystal of a shape memory alloy from a melt of the alloy. This is followed by heating, forming, 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: 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 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: We describe herein biocompatible single crystal Cu-based shape memory alloys (SMAs). In particular, we show biocompatibility based on MEM elution cell cytotoxicity, ISO intramuscular implant, and hemo-compatibility tests producing negative cytotoxic results. This biocompatibility may be attributed to the formation of a durable oxide surface layer analogous to the titanium oxide layer that inhibits body fluid reaction to titanium nickel alloys, and/or the non-existence of crystal domain boundaries may inhibit corrosive chemical attack. Methods for controlling the formation of the protective aluminum oxide layer are also described, as are devices including such biocompatible single crystal copper-based SMAs.

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 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: 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: 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.