2226 results about "Shear stress" patented technology

One or more rigid components associated with an articulating bone are used to encase, encapsulate, contain, or otherwise protect a compressible/resilient member. The embodiments are applicable not only to artificial disc replacement (ADR) devices, but also to joint situations including total knee and hip arthroplasty. The cushion elements in the preferred embodiments include synthetic rubbers, hydrogels, elastomers, and other polymeric materials such as viscoelastic polymers and foam polyurethanes. The invention effectively combines the advantages of such materials (cushioning, shape memory, and expansion after insertion in the case of hydrogels), while providing increased protection, particularly the elimination of shear stresses. When applied to an ADR, the invention also minimizes the risk of extrusion.

A method and soft tissue cleat device for improving the repair of soft tissue damage. A disc having projections pierces soft tissue and securely joins with a second disc to coapt the interposed soft tissue. This provides an increased pull-out strength of the suture and resistance to shear stresses, improving the quality of the repair. The present invention may be used with any bone fixation devices to reattach soft tissue to bone, and may also be used to rejoin soft tissues after a tear in the tissue.

Methods of medical treatment and diagnosis using mediators released by endothelial cells stimulated by external addition of pulses to the circulation are disclosed. The external pulses produce circumferential shear stress in body fluid channels that subsequently stimulates the endothelial cells to produce mediators that become available for therapeutic and diagnostic purposes. The preferred means of adding external pulses is the mechanical inducement of periodic acceleration of the body or parts of the body by a reciprocating motion platform.

One or more rigid components associated with an articulating bone are used to encase, encapsulate, contain, or otherwise protect a compressible/resilient member. The embodiments are applicable not only to artificial disc replacement (ADR) devices, but also to joint situations including total knee and hip arthroplasty. The cushion elements in the preferred embodiments include synthetic rubbers, hydrogels, elastomers, and other polymeric materials such as viscoelastic polymers and foam polyurethanes. The invention effectively combines the advantages of such materials (cushioning, shape memory, and expansion after insertion in the case of hydrogels), while providing increased protection, particularly the elimination of shear stresses. When applied to an ADR, the invention also minimizes the risk of extrusion.

A microfluidic platform for single-cell capture, stimulation, and imaging. It passively traps 4,000 single cells on a 4.5 mm² footprint in 30 seconds, with a single-cell loading efficiency of 95%. The array format and optimized geometry allows for easy, robust and efficient single-cell loading, while maintaining captured cells in a low shear stress environment for long-term studies. Because cells are captured sequentially, the system is adequate for rare cell samples. Trapped cells can be exposed to various environmental conditions and chemical stimulus and their dynamic response can be monitored over time. The information gained from high-throughput, single-cell time lapsed imaging presents new opportunities in quantifying cellular responses, as averaged information by other measurement methods eliminates sub-population phenotypes.

The invention provides devices that can be used to deliver a therapeutic agent to a treatment site within the vessel of a patient at increased pressure, while limiting the contact with and pressure placed on the vessel walls. Devices according to the invention include an expandable structure arranged around and on a tube having a lumen. The expandable structure may include a sealing ring that makes contact with the interior surface of a vessel to prevent or decrease fluid flow during delivery of a therapeutic agent. This allows delivery of a therapeutic agent with decreased risk of injury to the treatment site. The invention also provides for large lumen diameters, preventing shearing stress on therapeutic agents such as cell slurries.

According to embodiments of the present invention, a distributed pressure and shear stress sensor includes a flexible substrate, such as PDMS, with a waveguide formed thereon. Along the waveguide path are several Bragg gratings. Each Bragg grating has a characteristic Bragg wavelength that shifts in response to an applied load due to elongation/compression of the grating. The wavelength shifts are monitored using a single input and a single output for the waveguide to determine the amount of applied pressure on the gratings. To measure shear stress, two flexible substrates with the waveguide and Bragg gratings are placed on top of each other such that the waveguides and gratings are perpendicular to each other. To fabricate the distributive pressure and shear sensor, a unique micro-molding technique is used wherein gratings are stamped into PDMS, for example.

A method and apparatus is disclosed for providing shear-induced alignment of nanostructures, such as spherical nanodomains, self-assembled nanodomains, and particles, in thin films, such as block copolymer (BCP) thin films. A silicon substrate is provided, and a thin film is formed on the substrate. A pad is then applied to the thin film, and optionally, a weight can be positioned on the pad. Optionally, a thin fluid layer can be formed between the pad and the thin film to transmit shear stress to the thin film. The thin film is annealed and the pad slid in a lateral direction with respect to the substrate to impart a shear stress to the thin film during annealing. The shear stress aligns the nanostructures in the thin film. After annealing and application of the shear stress, the pad is removed, and the nanostructures are uniformly aligned.

Arthroplasty devices having improved bone in growth to provide a more secure connection within the body. Different embodiments disclosed include devices having threaded intramedullary components, devices configured to receive bone growth promoting substances, devices with resorbable components, and devices configured to reduce shear stress.

A method of forming a multilayer film is disclosed, comprising coextruding a first layer comprising a weatherable composition, and a second layer comprising a polycarbonate composition comprising a visual effect filler, wherein the first and second layers are formed by flowing each of the weatherable composition and polycarbonate composition through separate flow channels in a multi-manifold coextrusion die. The shear stress during extrusion on the polycarbonate composition is greater than or equal to 40 kilo-Pascals.

Arthroplasty devices having improved bone in growth to provide a more secure connection within the body. Different embodiments disclosed include devices having threaded intramedullary components, devices configured to receive bone growth promoting substances, devices with resorbable components, and devices configured to reduce shear stress.

When a substrate layer (desired semiconductor crystal) made of a group III nitride compound is grown on a base substrate comprising a lot of projection parts, a cavity in which a semiconductor crystal is not deposited may be formed between each projection part although it depends on conditions such as the size of each projection part, arranging interval between each projection part and crystal growth. So when the thickness of the substrate layer is sufficiently larger compared with the height of the projection part, inner stress or outer stress become easier to act intensively to the projection part. As a result, such stress especially functions as shearing stress toward the projection part. When the shearing stress becomes larger, the projection part is ruptured. So utilizing the shearing stress enables to separate the base substrate and the substrate layer easily. The larger the cavities are formed, the more stress tends to concentrate to the projection parts, to thereby enable to separate the base substrate and the substrate layer more securely.

The invention provides a method for forming polymer microrods, the method including the steps of providing a polymer solution comprising a polymer dissolved in a first solvent; providing a dispersion medium comprising a second solvent, wherein the first solvent and the second solvent are miscible or partially soluble in each other, and wherein the polymer is insoluble in the second solvent; adding the polymer solution to the dispersion medium to form a dispersed phase of polymer solution droplets within the dispersion medium; and introducing a shear stress to the dispersion medium and dispersed polymer solution droplets for a time and at a shear rate sufficient to elongate the polymer solution droplets to form microrods and solidify the microrods by attrition of the polymer solvent into the dispersion medium.

A device, system and method is disclosed in which small volume blood samples are subjected to shear forces and shear stresses between two parallel planar surfaces to which linear motion trajectories are imparted. The formation of clots or coagulation of the sample is measured from dynamic mechanical coupling which occurs between the two parallel planar surfaces. Detection of the coagulation response can be achieved through optical probing or by measurement of physical effects of the blood sample binding to the planar surfaces, and restricting movement thereof.

A stack of piezoelectric elements, in the form of an elongated rod divided in to segments, for generating electric energy in response to compressive stress is provided comprising: piezoelectric elements stacked one on top of the other such that electrodes of same polarity of adjacent disks are touching A holding structure, such as a screw holds the piezoelectric elements together between a top and a bottom end pieces which transfer mechanical compressive stress to the elements in the stack. The holding structure accepts shear stresses, provides preloading stress on the stack and prevents buckling of the stack under pressure. A recess in the end piece, deeper than the head of the screw, ensures that load placed on the stack will compress the piezoelectric elements and not on the screw.

Improved methods and apparatuses for directly monitoring well casing strain and structural integrity are disclosed that allows for monitoring of potentially damaging strain from any orientation or mode and over long stretches of well casing. In a preferred embodiment, optical fiber sensors are housed within a housing and attached to the exterior surface of the casing. The sensors may be aligned parallel, perpendicular, or at an appropriate angle to the axis of the casing to detect axial, hoop, and shear stresses respectively. The sensors are preferably interferometrically interrogatable and are capable of measuring both static and dynamic strains such as those emitted from microfractures in the well casing. Analysis of microfracture-induced acoustics includes techniques for assessment of relatively high frequencies indicative of the presence of microfractures. Assessment of the timing of the arrival of such acoustics at various sensors deployed along the casing further allows for the location of strain to be pinpointed.