1157 results about "Shape-memory polymer" patented technology

An adaptive optic for refractive lens exchange or cataract patients. The intracapsular implant comprises an elastomeric monolith with an equilibrium memory shape that imparts to the capsular sac's periphery the natural shape of the capsule in an accommodated state. In one embodiment, the monolith carries a recessed deformable central lens portion having an ultralow modulus that allows for high accommodative amplitude in response to equatorial tensioning. In a preferred embodiment, the adaptive optic defines an anisotropic modulus with a plurality of on-axis, rotationally symmetric elastomer block portions each having a different Young's modulus. The invention further provides composite materials for enhancing deformation of lens curvature, including the use of auxetic polymeric materials and negative stiffness materials. In preferred embodiments, at least a portion of the lens is fabricated of a shape memory polymer that provides a memory shape and a temporary shape with a reduced cross-sectional shape for introduction into the patient's eye.

A self-expanding medical occlusion device treats a heart defect in a patient and is inserted into the body in minimally invasive fashion using a catheter system, and includes a braiding of thin threads which exhibits a first preliminarily definable shape as the occlusion device is being inserted into the patient's body and a second preliminarily definable shape in the implanted state, whereby the occlusion device is in a collapsed state in the first shape of the braiding and in an expanded state in the second shape of the braiding. The threads of braiding are composed of a shape memory polymer composite such that braiding deforms from a temporary shape to a permanent shape in consequence of an external stimulus, whereby the temporary shape is given in a first profile form of the braiding and the permanent shape is given in a second profile form of the braiding.

This invention relates to a orthopedic implant that comprises a shape memory polymeric material. The orthopedic implant can be fabricated or molded in a desired configuration selected to provide support or tension to bony structures. Examples of implantable devices include spinal rods, bone plates, and bone fixation cords. The orthopedic implant can be deformed to a second configuration different from the first configuration either prior to implantation or after implantation. When desired, the shape memory polymeric material can be induced to revert to it original molded configuration. This can compress the attached bony structure and / or promote arthrodesis.

A screen section has a valve assembly to control flow through it. The valve is open and has a closure spring held compressed by a shape memory material that responds to the presence of a specific well fluid or fluids so that its property changes to allow the spring to deliver the stored potential energy to the valve member to close it when the specific well fluid or fluids are detected. The preferred material is a shape memory polymer that, for example, is sensitive to the presence of water or methane and gets softer to release the potential energy source to operate the downhole tool.

Medical devices for in vivo medical applications are disclosed. The medical devices are constructed of shape memory polymer (SMP) materials capable of assuming a memory shape at physiological temperatures. These medical devices may be used in surgical procedures and in both vascular and non-vascular applications. These SMP medical devices have a post-implantation memory shape that is substantially identical to or slightly larger than the insertion site to adapt to vessel growth or size changes. SMP medical devices may be formed as stents or occlusion devices (i.e., plugs) having a number of different structural features. The SMP medical devices may be formed from a first monomer and a second cross-linking monomer, wherein the weight percentages of the first and second monomers are selected by performing an iterative function to reach a predetermined glass transition temperature (Tg) and a predetermined rubbery modulus to optimize post-implantation memory shape properties of the devices.

A bistable electroactive polymer transducer is provided for electrically actuated deformation of rigid electroactive polymer members. The polymers have glass transition temperatures (Tg) above ambient conditions and turn into rubbery elastomers above Tg and have high dielectric breakdown strength in the rubbery state. They can be electrically deformed to various rigid shapes with maximum strain greater than 100% and as high as 400%. The actuation is made bistable by cooling below Tg to preserve the deformation. The dielectric actuation mechanism includes a pair of compliant electrodes in contact with a dielectric elastomer which deforms when a voltage bias is applied between the pair of electrodes. In some of the transducers of the present invention, the dielectric elastomer is also a shape memory polymer. The deformations of such bistable electroactive polymers can be repeated rapidly for numerous cycles. The polymer transducers have such advantages as high energy and power densities, quietness, mechanical compliancy (for shock resistance and impedance matching), high efficiency, lightweight, and low cost.

An apparatus for controlling fluid flow in a wellbore includes a reactive element that reacts when exposed to a fluid and a flow control device configured to control a flow of the fluid. The flow control device may be actuated by a reaction of the reactive element to the fluid. In embodiments, the reactive element reacts by exhibiting a change in a material property. The reaction of the reactive element may be reversible. In embodiments, the reactive element may be a shape memory polymer. The flow control device may include an actuating element operably coupled to the reactive element. The reaction of the reactive element to a given fluid releases the actuating element to actuate the flow control device.

Endolumenal prostheses that readily and extensively convert from a delivery configuration to a deployed configuration are disclosed. Endolumenal prostheses may be fabricated from one or more shape memory polymers, a high modulus elastomer, a polymer that is both elastomeric and exhibits shape memory behavior, a hydrogel, or some combination thereof. Polymers used to fabricate the prostheses are selectively synthesized to exhibit desired characteristics such as crystallinity, strain fixity rate, strain recovery rate, elasticity, tensile strength, mechanical strength, cross-linking density, extent physical cross-linking, extent of covalent cross-linking, extent of interpenetrating networks, rate of erosion, heat of fusion, crystallization temperature, and acidity during erosion. The endolumenal prostheses convert to the deployed configuration following delivery to a treatment site, upon exposure to an initiator either present within the body naturally or introduced into the body.

Catheter assembly including an elongate shaft comprising a thermoplastic polymer such as a thermoplastic shape memory polymer having a pre-selected glass transition temperature (Tg) and a means for heating the thermoplastic polymer, wherein the thermoplastic polymer is in a rubbery state at temperatures above the glass transition temperature and is in a glassy state at temperatures below the glass transition temperature. The elongate shaft may be selectively heated and cooled to provide sufficient flexibility and retention during a medical procedure.

A hood lift mechanism for reversibly increasing the energy absorption capability at appropriate force levels of a vehicle hood includes a vehicle hood; an active material in operative communication with the vehicle hood, wherein the active material comprises a shape memory alloy, a ferromagnetic shape memory alloy, a shape memory polymer, a magnetorheological fluid, an electroactive polymer, a magnetorheological elastomer, an electrorheological fluid, a piezoelectric material, an ionic polymer metal composite, or combinations comprising at least one of the foregoing active materials; and an activation device in operative communication with the active material, wherein the activation device is operable to selectively apply an activation signal to the active material and effect a reversible change in a property of the active material, wherein the reversible change results in an increased clearance distance between the vehicle hood and an underlying component.

A bistable electroactive polymer transducer is provided for electrically actuated deformation of rigid electroactive polymer members. The polymers have glass transition temperatures (Tg) above ambient conditions and turn into rubbery elastomers above Tg and have high dielectric breakdown strength in the rubbery state. They can be electrically deformed to various rigid shapes with maximum strain greater than 100% and as high as 400%. The actuation is made bistable by cooling below Tg to preserve the deformation. The dielectric actuation mechanism includes a pair of compliant electrodes in contact with a dielectric elastomer which deforms when a voltage bias is applied between the pair of electrodes. In some of the configurations, the dielectric elastomer is also a shape memory polymer. The deformations of such bistable electroactive polymers can be repeated rapidly for numerous cycles.

An implantable medical electrical lead for electrical stimulation of body tissue that includes at least one shape memory polymer portion that has a first configuration and a second configuration, wherein the second configuration is obtained upon exposure of the shape memory polymer portion to a transition stimulus, and wherein the second configuration of the modifiable portion exhibits a greater resistance to movement of the lead within the body tissue than does the first configuration; and at least one electrode configured to provide electrical stimulation of body tissue, wherein the lead has a proximal end and a distal end. Systems and kits as well as methods of utilizing the leads of the invention are also included.

Devices for treatments of diseases and disorders associated with the gastrointestinal tract, especially the stomach, or urinogenital tract are described herein. Initially, the device is in a temporary form which is suitable for oral or rectal administration. After exposure to a stimulus, such as a temperature or pH change, the device changes shape to a permanent form, which allows it to become mechanically fixed in the stomach, esophagus or intestine. In one embodiment, the device is used to reduce the volume of the stomach, esophagus or intestine without interfering with the flow of the food through the gastrointestinal tract. The device may be used to help overweight patients lose weight and to deliver drugs to treat disorders and diseases in the in the stomach or intestine. The devices are manufactured from a stimuli-sensitive polymeric material, which is biocompatible and primarily adapted to the mechanical properties and geometry in the area to which it is applied. In the preferred embodiment, the material is a shape memory polymer. Depending on the desired application, the polymer may be either biodegradable or non-degradable.

Thermoplastic polyurethanes having an alternating sequence of hard and soft segments in which a nanostructured polyhedral oligomeric silsesquioxane diol is used as a chain extender to form a crystalline hard segment constituting SMPs. The polyurethanes are formed by reacting a polyol, a chain extender dihydroxyl-terminated POSS and a diisocyanate. The polyurethanes have multiple applications including for example, implants for human health care, drug delivery matrices, superabsorbant hydrogels, coatings, adhesives, temperature and moisture sensors, etc.