scholarly journals Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Andrea D. Muschenborn ◽  
Keith Hearon ◽  
Brent L. Volk ◽  
Jordan W. Conway ◽  
Duncan J. Maitland
Keyword(s):  
Crosslink Density ◽  
Blood Clot ◽  
Shape Memory Polymer ◽  
Thermomechanical Properties ◽  
Recovery Stress ◽  
Element Analysis ◽  
Clot Removal ◽  
Acrylic Copolymers ◽  
Thrombectomy Device ◽  
And Performance

Purpose. To evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery. Methods. Four thermoset acrylic copolymers containing benzyl methacrylate (BzMA) and bisphenol A ethoxylate diacrylate (Mn∼512, BPA) were designed with differing thermomechanical properties. Finite element analysis (FEA) was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy. Results. Devices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole% BPA devices endured all testing and their recovery stress (5 kPa) enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content. Conclusion. While the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application.

Effects of Discontinuous Fiber Reinforcement on the Mechanical and Thermomechanical Properties of a Shape Memory Polymer

2007 ◽  
Author(s):  
Michael B. Lyons ◽  
Robin Shandas
Keyword(s):  
Shape Memory ◽  
Production Cost ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Thermomechanical Properties ◽  
Large Strains ◽  
Cardiovascular Stents ◽  
Clot Removal ◽  
Discontinuous Fiber ◽  
Removal System

Over the last few years, we have developed shape memory polymers (SMPs) with several properties suitable for use in minimally-invasive biomedical devices. These properties include biocompatibility, the ability to fully recover large strains, the potential to serve as medication reservoirs for drug delivery, and low production cost. We and others have proposed use of shape memory polymers for various applications including cardiovascular stents, an endovascular clot removal system, and a self-tying suture.

Shape Memory Alloy Clip for Compression Colonic Anastomosis

2004 ◽  
Vol 127 (2) ◽  
pp. 351-354 ◽  
Author(s):  
Chengli Song ◽  
Tim Frank ◽  
Alfred Cuschieri
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Computer Aided Design ◽  
Colonic Anastomosis ◽  
Material Model ◽  
Colon Surgery ◽  
Thermomechanical Properties ◽  
Nonlinear Material ◽  
Element Analysis ◽  
And Performance

This study was setup to investigate the design and performance of a shape memory alloy clip for colonic anastomosis. The thermomechanical properties of the shape memory alloy material were studied and the data were used to derive a nonlinear material model. This enabled the development of computer computer aided design models and finite element analysis of the clip and tissue compression. The maximum strain of the anastomosis clip was within the recoverable range, and it exerted parallel compression of the colonic walls with a uniform pressure distribution. The design of the anastomosis clip was optimized for safe, simple, and effective use in colon surgery.

Shape fixity and shape recovery of polyurethane shape-memory polymer foams

2003 ◽  
Vol 217 (2) ◽  
pp. 135-143 ◽  
Author(s):  
H Tobushi ◽  
D Shimada ◽  
S Hayashi ◽  
M Endo
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymer ◽  
High Temperature Stress ◽  
Thermomechanical Properties ◽  
Recovery Stress ◽  
Original Shape ◽  
Number Of Cycles ◽  
Shape Fixity

The thermomechanical properties of polyurethane shape memory polymer (SMP) foams were investigated experimentally. The results obtained can be summarized as follows. (1) By cooling the foam after compressive deformation at high temperature, stress decreases and the deformed shape is fixed. Stress decreases markedly in the region of temperature below the glass transition temperature Ts during the cooling process. (2) By heating the shape-fixed foam under no load, the original shape is recovered. Strain is recovered markedly at the temperature region in the vicinity of Tg. (3) The ratio of shape fixity is 100 per cent and that of shape recovery 98 per cent. Neither ratio depends on the number of cycles. (4) Recovery stress increases by heating under constraint of the fixed shape. Recovery stress is about 80 per cent of the applied maximum stress. Relaxed stress at high temperature is not recovered. (5) The shape deformed at high temperature is maintained for six months under no load at Tg’60 K without depending on maximum strain, and the original shape is recovered by heating thereafter. (6) If the deformed shape is kept at high temperature, the original shape is not recovered. The factors influencing the shape irrecovery are the holding conditions of strain, temperature, and time.

Quantifying the mechanical and histological properties of thrombus analog made from human blood for the creation of synthetic thrombus for thrombectomy device testing

2018 ◽  
Vol 10 (12) ◽  
pp. 1168-1173 ◽  
Author(s):  
William Merritt ◽  
Anne Marie Holter ◽  
Sharna Beahm ◽  
Connor Gonzalez ◽  
Timothy A Becker ◽  
...  
Keyword(s):  
Human Blood ◽  
Ex Vivo ◽  
Blood Clot ◽  
Testing System ◽  
Interpenetrating Network ◽  
Shear Moduli ◽  
Clot Removal ◽  
Blood Clots ◽  
Thrombectomy Device

BackgroundUntreated ischemic stroke can lead to severe morbidity and death, and as such, there are numerous endovascular blood-clot removal (thrombectomy) devices approved for human use. Human thrombi types are highly variable and are typically classified in qualitative terms – ‘soft/red,’ ‘hard/white,’ or ‘aged/calcified.’ Quantifying human thrombus properties can accelerate the development of thrombus analogs for the study of thrombectomy outcomes, which are often inconsistent among treated patients.Methods‘Soft’human thrombi were created from blood samples ex vivo (ie, human blood clotted in sample vials) and tested for mechanical properties using a hybrid rheometer material testing system. Synthetic thrombus materials were also mechanically tested and compared with the ‘soft’ human blood clots.ResultsMechanical testing quantified the shear modulus and dynamic (elastic) modulus of volunteer human thrombus samples. This data was used to formulate a synthetic blood clot made from a composite polymer hydrogel of polyacrylamide and alginate (PAAM-Alg). The PAAM-Alg interpenetrating network of covalently and ionically cross-linked polymers had tunable elastic and shear moduli properties and shape memory characteristics.ConclusionsDue to its adjustable properties, PAAM-Alg can be modified to mimic various thrombi classifications. Future studies will include obtaining and quantitatively classifying patient thrombectomy samples and altering the PAAM-Alg to mimic the results for use with in vitro thrombectomy studies.

Materials Issues and Characterization of Low-k Dielectric Materials

MRS Bulletin ◽  
1997 ◽  
Vol 22 (10) ◽  
pp. 49-54 ◽  
Author(s):  
E. Todd Ryan ◽  
Andrew J. McKerrow ◽  
Jihperng Leu ◽  
Paul S. Ho
Keyword(s):  
Process Integration ◽  
Dielectric Materials ◽  
Propagation Delay ◽  
Thermomechanical Properties ◽  
General Criterion ◽  
Crosstalk Noise ◽  
Total Delay ◽  
Interlayer Dielectrics ◽  
Performance Improvements ◽  
And Performance

Continuing improvement in device density and performance has significantly affected the dimensions and complexity of the wiring structure for on-chip interconnects. These enhancements have led to a reduction in the wiring pitch and an increase in the number of wiring levels to fulfill demands for density and performance improvements. As device dimensions shrink to less than 0.25 μm, the propagation delay, crosstalk noise, and power dissipation due to resistance-capacitance (RC) coupling become significant. Accordingly the interconnect delay now constitutes a major fraction of the total delay limiting the overall chip performance. Equally important is the processing complexity due to an increase in the number of wiring levels. This inevitably drives cost up by lowering the manufacturing yield due to an increase in defects and processing complexity.To address these problems, new materials for use as metal lines and interlayer dielectrics (ILDs) and alternative architectures have surfaced to replace the current Al(Cu)/SiO2 interconnect technology. These alternative architectures will require the introduction of low-dielectric-constant k materials as the interlayer dielectrics and/or low-resistivity conductors such as copper. The electrical and thermomechanical properties of SiO2 are ideal for ILD applications, and a change to material with different properties has important process-integration implications. To facilitate the choice of an alternative ILD, it is necessary to establish general criterion for evaluating thin-film properties of candidate low-k materials, which can be later correlated with process-integration problems.

Investigate of Electrical Conductivity of Shape-Memory Polymer Filled with Carbon Black

2008 ◽  
Vol 47-50 ◽  
pp. 714-717 ◽  
Author(s):  
Xin Lan ◽  
Jin Song Leng ◽  
Yan Ju Liu ◽  
Shan Yi Du
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Shape Memory ◽  
Shape Recovery ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Recovery Process ◽  
Thermomechanical Properties ◽  
Electrically Conductive ◽  
New System

A new system of thermoset styrene-based shape-memory polymer (SMP) filled with carbon black (CB) is investigated. To realize the electroactive stimuli of SMP, the electrical conductivity of SMP filled with various amounts of CB is characterized. The percolation threshold of electrically conductive SMP filled with CB is about 3% (volume fraction of CB), which is much lower than many other electrically conductive polymers. When applying a voltage of 30V, the shape recovery process of SMP/CB(10 vol%) can be realized in about 100s. In addition, the thermomechanical properties are also characterized by differential scanning calorimetery (DSC).

Thermomechanical properties of shape memory polymer subjected to tension in various conditions

2009 ◽  
Vol 6 (2) ◽  
pp. 189-205 ◽  
Author(s):  
Elzbieta A. Pieczyska ◽  
Wojciech K. Nowacki ◽  
Hisaaki Tobushi ◽  
Shunichi Hayashi
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Thermomechanical Properties

Tensegrity Structures in the Design of Flexible Structures for Offshore Aquaculture

2007 ◽  
Author(s):  
O̸sten Jensen ◽  
Anders Sunde Wroldsen ◽  
Pa˚l Furset Lader ◽  
Arne Fredheim ◽  
Mats Heide ◽  
...  
Keyword(s):  
Flexible Structures ◽  
Weather Conditions ◽  
High Energy ◽  
Open Ocean ◽  
Element Analysis ◽  
Tensegrity Structures ◽  
Stiffness Properties ◽  
Offshore Aquaculture ◽  
And Performance ◽  
Open Ocean Aquaculture

Aquaculture is the fastest growing food producing sector in the world. Considerable interest exists in developing open ocean aquaculture in response to a shortage of suitable, sheltered inshore locations. The harsh weather conditions experienced offshore lead to a focus on new structure concepts, remote monitoring and a higher degree of automation in order to keep the cost of structures and operations within an economically viable range. This paper proposes tensegrity structures in the design of flexible structures for offshore aquaculture. The finite element analysis program ABAQUS™ has been used to investigate stiffness properties and performance of tensegrity structures when subjected to various forced deformations and hydrodynamic load conditions. The suggested concept, the tensegrity beam, shows promising stiffness properties in tension, compression and bending, which are relevant for development of open ocean aquaculture construction for high energy environments. When designing a tensegrity beam, both pre-stress and spring stiffness should be considered to ensure the desired structural properties. A large strength to mass ratio and promising properties with respect to control of geometry, stiffness and vibration could make tensegrity an enabling technology for future developments.

Sign in / Sign up

Export Citation Format

Share Document