scholarly journals Mechanically Robust, Softening Shape Memory Polymer Probes for Intracortical Recording

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 619 ◽  
Author(s):  
Allison Stiller ◽  
Joshua Usoro ◽  
Jennifer Lawson ◽  
Betsiti Araya ◽  
María González-González ◽  
...  
Keyword(s):  
Shape Memory ◽  
Room Temperature ◽  
Shape Memory Polymer ◽  
Microelectrode Arrays ◽  
Device Fabrication ◽  
High Modulus ◽  
Mechanical Instability ◽  
Rat Cortex ◽  
Clinical Scenarios ◽  
Stiff Material

While intracortical microelectrode arrays (MEAs) may be useful in a variety of basic and clinical scenarios, their implementation is hindered by a variety of factors, many of which are related to the stiff material composition of the device. MEAs are often fabricated from high modulus materials such as silicon, leaving devices vulnerable to brittle fracture and thus complicating device fabrication and handling. For this reason, polymer-based devices are being heavily investigated; however, their implementation is often difficult due to mechanical instability that requires insertion aids during implantation. In this study, we design and fabricate intracortical MEAs from a shape memory polymer (SMP) substrate that remains stiff at room temperature but softens to 20 MPa after implantation, therefore allowing the device to be implanted without aids. We demonstrate chronic recordings and electrochemical measurements for 16 weeks in rat cortex and show that the devices are robust to physical deformation, therefore making them advantageous for surgical implementation.

Characristics of Shape Memory Composites Combined with Shape Memory Alloy and Shape Memory Polymer

2013 ◽  
Vol 705 ◽  
pp. 169-172
Author(s):  
Xue Feng ◽  
Li Min Zhao ◽  
Xu Jun Mi
Keyword(s):  
Shape Memory ◽  
Room Temperature ◽  
Shape Recovery ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Young Modulus ◽  
Thermomechanical Properties ◽  
The Matrix ◽  
Shape Memory Composites ◽  
Shape Fixity

In order to develop high functionality of shape memory materials, the shape memory composites combined with TiNi wire and shape memory epoxy were prepared, and the mechanical and thermomechanical properties were studied. The results showed the addition of TiNi wire increased the Young modulus and breaking strength both at room temperature and at elevated temperature. The composites maintained the rates of shape fixity and shape recovery close to 100%. The maximum recovery stress increased with increasing TiNi wire volume fraction, and obtained almost 3 times of the matrix by adding 1vol% TiNi wire.

Design of variable stiffness fixture for computerized embroidery machine based on shape memory polymer

2022 ◽  
pp. 1045389X2110721
Author(s):  
Yawen Yang ◽  
Lei Tian ◽  
Xi Chen ◽  
Jiayuan Wang ◽  
Yongyan Zhang ◽  
...  
Keyword(s):  
Shape Memory ◽  
Material Properties ◽  
Room Temperature ◽  
Working Condition ◽  
Raw Materials ◽  
Shape Memory Polymer ◽  
Variable Stiffness ◽  
Fixture Design ◽  
Stiffness Characteristic ◽  
The Relationship

It is a challenge to handle the metal fixture used for cloth clamping in a computerized embroidery machine because of its fixed stiffness. Herein, a prototype that acts as a fixture to provide variable stiffness property is explored by discussing the potential of a thermal-sensitive epoxy resin-based shape memory polymer (SMP). The general model of fixture design is obtained after analyzing the working condition of the metal fixture. The structure of the SMP fixture is designed by discussing the material properties and working requirements of SMP, and a theoretical model is established to deduce the relationship between thickness and stiffness of the fixture. Six SMP fixtures that memorized clamping and opening state were manufactured with different proportions of raw materials. The results show that the designed fixtures have a lighter weight but higher clamping force than the metal fixture at room temperature (RT). It is the first work that demonstrates the potential of the SMP fixture to replace the metal fixture in the computerized embroidery machine and provides inspiration for product design with variable stiffness characteristic in engineering.

Method to Analyze Chemo-Mechanical Behavior of Shape Memory Polymer in Response to Solvent

2011 ◽  
Vol 230-232 ◽  
pp. 21-25
Author(s):  
Hai Bao Lu ◽  
Jin Ying Yin ◽  
Jiu Si Jia
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Chemical Potential ◽  
Shape Memory Polymer ◽  
Entropy Change ◽  
Dipole Interaction ◽  
Positive Definite ◽  
Free Energy Function ◽  
Mechanical Instability ◽  
Recovery Behavior

Thermo-responsive shape-memory polymer (SMP) has been experimentally demonstrated that shape recovery can be induced by plasticizing solvent. Subject to being immersed into solvent, deformed SMP recover from the temporary shape to original shape, leading to shape recovery induced by the molecular interaction. The actuation of styrene-based SMP has been carried out by electrostatic dipole-dipole interaction and physical swelling effect, respectively. The model can be used to predict the effect of prestress, strain, volume change and chemical potential on SMP actuation in the solvent. Finally, it is found that the simulation agrees well with experimental results. The authors show that the chemo-mechanical instability occurs when the Hessian of the free-energy function ceases to the positive definite. Their calculations show that the shape recovery behavior of SMP is driven by the entropy change markedly, agreeing with existing experimental observations.

Towards Novel Light-Activated Shape Memory Polymer: Thermomechanical Properties of Photo-responsive Polymers

2005 ◽  
Vol 872 ◽  
Author(s):  
Emily A. Snyder ◽  
Tat H. Tong
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Room Temperature ◽  
Shape Memory Polymer ◽  
Crosslinking Density ◽  
Material System ◽  
Effect Change ◽  
Responsive Polymers ◽  
Original Shape

AbstractThe basic principle for the operation of a thermally stimulated shape memory polymer (SMP) is a drastic change in elastic modulus above the glass transition temperature (Tg). This change from glassy modulus to rubbery modulus allows the material to be deformed above the Tg and retain the deformed shape when cooled below the Tg. The material will recover its original shape when heated above the Tg again. However, thermal activation is not the only possibility for a polymer to exhibit this shape memory effect or change of modulus. This paper discusses results of an alternative approach to SMP activation.It is well known that the Tg of a thermosetting polymer is proportional to its crosslinking density. It is possible for the crosslinking density of a room temperature elastomer to be modified through photo-crosslinking special photo-reactive monomer groups incorporated into the material system in order to increase its Tg. Correspondingly, the modulus will be increased from the rubbery state to the glassy state. As a result, the material is transformed from an elastomer to a rigid glassy photoset, depending on the crosslinking density achieved during exposure to the proper wavelength of light. This crosslinking process is reversible by irradiation with a different wavelength, thus making it possible to produce light-activated SMP materials that could be deformed at room temperature, held in deformed shape by photo-irradiation using one wavelength, and recovered to the original shape by irradiation with a different wavelength.In this work, monomers which contain photo-crosslinkable groups in addition to the primary polymerizable groups were synthesized. These monomers were formulated and cured with other monomers to form photo-responsive polymers. The mechanical properties of these materials, the kinetics, and the reversibility of the photo-activated shape memory effect were studied to demonstrate the effectiveness of using photo-irradiation to effect change in modulus (and thus shape memory effect).

Light-Activated Hydrophobic Adhesive for Shape-Memory Polymer Nerve Cuffs

MRS Advances ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 1-7
Author(s):  
Victoria Wobser ◽  
Kejia Yang ◽  
Romil Modi ◽  
Wyatt Archer ◽  
Yogi Patel ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shape Memory ◽  
Room Temperature ◽  
Shape Memory Polymer ◽  
Hydrophobic Polymers ◽  
Nerve Cuff ◽  
Lap Shear

ABSTRACTIn this study, three hydrophobic polymers are investigated as potential adhesives for a shape memory polymer nerve cuff. At room temperature, the adhesive candidate exhibited a maximum lap shear stress of 1.7251 MPa, compared to 0.87641 MPa and 2.1815 MPa for two commercially available biocompatible adhesives.

Deployment performance of shape memory polymer composite hinges at low temperature

2019 ◽  
Vol 30 (17) ◽  
pp. 2625-2638 ◽  
Author(s):  
Van Luong Le ◽  
Vinh Tung Le ◽  
Nam Seo Goo
Keyword(s):  
Low Temperature ◽  
Shape Memory ◽  
Polymer Composite ◽  
Room Temperature ◽  
Shape Memory Polymer ◽  
Heating Element ◽  
Heating Process ◽  
Space Applications ◽  
Design Modification ◽  
The Impact

Shape memory polymer composite hinges, adapted for possible space applications, were successfully designed and fabricated, and performance tests at room temperature confirmed their full recoverability in our previous studies. Since shape memory polymer composite hinges are intended for space applications, they should be able to operate at low temperature. Even though the deployment of the hinge at room temperature triggered by the stimulation of a heating element has been quite promising, a suitable design for a shape memory polymer composite hinge with a heating element is more important at low temperatures because shape memory polymer composite hinges lose much heat to the environment. The recoverability of shape memory polymer composite hinges and the impact of the heating element design on the deployment time at low temperature are brought to light in this article. A shape memory polymer composite hinge with an attached heating element was fabricated as in our previous studies. The necessary power and supply power for deployment of the shape memory polymer composite hinge at a low temperature of –10°C were calculated, and a finite element analysis for the heating process was performed with the supply power. A folding and deployment test of the shape memory polymer composite hinge at –10°C was performed to show its shape recoverability. However, the shape memory polymer composite hinge did not deploy to its original shape. To determine the reason, measurements of temperature distribution were done using an infrared camera and thermocouples. The results revealed that the low temperature along the two side edges of the shape memory polymer composite tape prevented full deployment of the shape memory polymer composite hinge, which also revealed the need for design modification. The folding and deployment test of our modified shape memory polymer composite hinge demonstrated a nearly full deployment.

Toward the low actuation temperature of flexible shape memory polymer composites with room temperature deformability via induced plasticizing effect

2017 ◽  
Vol 5 (44) ◽  
pp. 8845-8853 ◽  
Author(s):  
Shenyang Cai ◽  
Yu-Chen Sun ◽  
Jie Ren ◽  
Hani E. Naguib
Keyword(s):  
Low Temperature ◽  
Shape Memory ◽  
Polymer Composites ◽  
Room Temperature ◽  
Shape Memory Polymer ◽  
Shape Memory Properties

Room temperature deformable PLA/TPU/PEG blends demostrate superior shape memory properties under low temperature environments due to the induced plasticizing effect.

Hybrid Electroactive Shape Memory Polymer Composites with Room Temperature Deformability

2019 ◽  
Vol 304 (10) ◽  
pp. 1900196 ◽  
Author(s):  
Yu‐Chen Sun ◽  
Marco Chu ◽  
Morris Huang ◽  
Omer Hegazi ◽  
Hani E. Naguib
Keyword(s):  
Shape Memory ◽  
Polymer Composites ◽  
Room Temperature ◽  
Shape Memory Polymer

Effect of C12-14 Alcohols on the Thermomechanical Properties of Epoxy Shape-Memory Polymer

2014 ◽  
Vol 787 ◽  
pp. 275-280
Author(s):  
Li Min Zhao ◽  
Xue Feng ◽  
Xu Jun Mi ◽  
Yan Feng Li ◽  
Hao Feng Xie ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Shape Memory ◽  
Room Temperature ◽  
Aliphatic Alcohol ◽  
Shape Memory Polymer ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Epoxy System ◽  
Scanning Calorimetry ◽  
Epoxy Polymers

A critical parameter for a shape memory polymer (SMP) lies in its shape memory transition temperature. For an amorphous SMP polymer, it is highly desirable to develop methods to tailor its Tg, which corresponds to its shape memory transition temperature. Starting with an amine cured aromatic epoxy system, epoxy polymers were synthesized by introducing flexible aliphatic alcohol. The thermal and thermomechanical properties of these epoxy polymers were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). All the crosslinked epoxy polymers with Tg’s above room temperature were found to possess shape memory properties.

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