Multiscale Study on Effect of Humidity on Shape Memory Polymers Used in 3D Printing

2021 ◽  
pp. 1-25
Author(s):  
Frank Livolsli ◽  
Thomas May ◽  
Dylan Caputo ◽  
Kamran Fouladi ◽  
Babak Eslami
Keyword(s):  
3D Printing ◽  
Shape Memory ◽  
Fluid Dynamic ◽  
Shape Memory Polymers ◽  
3 Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Macro Scale ◽  
3D Printed ◽  
Scale Characterization

Abstract Shape memory polymers (SMP) are used in the 3D printing field for different applications such as soft robotics or medical devices. Although this technology has expanded the capabilities of additive manufacturing, there still exists fundamental questions regarding the optimum condition for manufacturing these 3D printed parts. Various factors play a crucial role in the final quality of printed parts, such as deposition orientation, percentage infill, or environmental conditions. In this paper, we study the effect of humidity on commercially available SMPs (NinjaFlex©) at both micro- and macro-scale. By performing a 3-dimensional computational fluid dynamic model for the printing environment, it is found there are significant temperature and humidity fluctuations around the hot-end and printing bed. Macro-scale characterization through ASTM D638 tensile testing shows that for humidity levels higher than 60% there is 5-10% reduction in the strength of material (ultimate strength and tangent modulus). This study is verified by micro-scale characterization performed with atomic force microscopy on thin-films. It is shown that in addition to the effect of humidity on the stiffness of materials, there is an effect on the loss moduli of the matter as well. As humidity increases, these polymers become more viscoelastic. Simultaneously, it is shown higher humidity levels cause increased micro-level surface roughness, which can be the cause for the strength reduction for higher humidities.

scholarly journals 3D Printed Shape Memory Polymers Produced via Direct Pellet Extrusion

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 87
Author(s):  
Trenton Cersoli ◽  
Alexis Cresanto ◽  
Callan Herberger ◽  
Eric MacDonald ◽  
Pedro Cortes
Keyword(s):  
3D Printing ◽  
Shape Memory ◽  
Memory Performance ◽  
Shape Memory Polymer ◽  
Shape Memory Polymers ◽  
Qr Code ◽  
Thermal Stimulus ◽  
Conventional Film ◽  
3D Printed ◽  
Smart Actuator

Shape memory polymers (SMPs) are materials capable of changing their structural configuration from a fixed shape to a temporary shape, and vice versa when subjected to a thermal stimulus. The present work has investigated the 3D printing process of a shape memory polymer (SMP)-based polyurethane using a material extrusion technology. Here, SMP pellets were fed into a printing unit, and actuating coupons were manufactured. In contrast to the conventional film-casting manufacturing processes of SMPs, the use of 3D printing allows the production of complex parts for smart electronics and morphing structures. In the present work, the memory performance of the actuating structure was investigated, and their fundamental recovery and mechanical properties were characterized. The preliminary results show that the assembled structures were able to recover their original conformation following a thermal input. The printed parts were also stamped with a QR code on the surface to include an unclonable pattern for addressing counterfeit features. The stamped coupons were subjected to a deformation-recovery shape process, and it was observed that the QR code was recognized after the parts returned to their original shape. The combination of shape memory effect with authentication features allows for a new dimension of counterfeit thwarting. The 3D-printed SMP parts in this work were also combined with shape memory alloys to create a smart actuator to act as a two-way switch to control data collection of a microcontroller.

Material Property Characterization of Costal Cartilage Using AFM Indentation

2009 ◽  
Author(s):  
S. Tripathy ◽  
E. J. Berger
Keyword(s):  
Material Characterization ◽  
Costal Cartilage ◽  
Indentation Modulus ◽  
Hertz Contact ◽  
Force Microscopy ◽  
Afm Indentation ◽  
Atomic Force ◽  
Macro Scale ◽  
Property Characterization

Costal cartilage is one of the load bearing tissues of the rib cage. Literature on the material characterization of the costal cartilage is limited. Atomic force microscopy has been extremely successful in characterizing the elastic properties of articular cartilage, but no studies have been published on costal cartilage. In this study AFM indentations on human costal cartilage were performed and compared with macro scale indentation data. Spherical beaded tips of three sizes were used for the AFM indentations. The Hertz contact model for spherical indenter was used to analyze the data and obtain the Young’s modulus. The costal cartilage was found to be almost linearly elastic till 600 nm of indentation depth. It was also found that the modulus values decreased with the distance from the junction. The modulus values from macro indentations were found to be 2-fold larger than the AFM indentation modulus.

Physical characterization and in vitro evaluation of 3D printed hydroxyapatite, tricalcium phosphate, zirconia, alumina, and SiAlON structures made by lithographic ceramic manufacturing

MRS Advances ◽  
2020 ◽  
Vol 5 (46-47) ◽  
pp. 2419-2428
Author(s):  
Alexander K. Nguyen ◽  
Peter L. Goering ◽  
Shelby A. Skoog ◽  
Roger J. Narayan
Keyword(s):  
Tricalcium Phosphate ◽  
Force Microscopy ◽  
Atomic Force ◽  
3D Printed ◽  
Ceramic Manufacturing ◽  
Surface Morphologies ◽  
Combination Of Material ◽  
Amorphous Character ◽  
Cells Cultured

AbstractIn this study, lithographic ceramic manufacturing was used to create solid chips out of hydroxyapatite, tricalcium phosphate, zirconia, alumina, and SiAlON ceramic. X-ray powder diffraction of each material confirmed that the chips were crystalline, with little amorphous character that could result from remaining polymeric binder, and were composed entirely out of the ceramic feedstock. Surface morphologies and roughnesses were characterized using atomic force microscopy. Human bone marrow stem cells cultured with osteogenic supplements on each material type expressed alkaline phosphatase levels, an early marker of osteogenic differentiation, on par with cells cultured on a glass control. However, cells cultured on the tricalcium phosphate-containing material expressed lower levels of ALP suggesting that osteoinduction was impaired on this material. Further analyses should be conducted with these materials to identify underlying issues of the combination of material and analysis method.

scholarly journals 3D Printing: 3D Printing of Shape Memory Polymers for Flexible Electronic Devices (Adv. Mater. 22/2016)

2016 ◽  
Vol 28 (22) ◽  
pp. 4166-4166 ◽  
Author(s):  
Matt Zarek ◽  
Michael Layani ◽  
Ido Cooperstein ◽  
Ela Sachyani ◽  
Daniel Cohn ◽  
...  
Keyword(s):  
3D Printing ◽  
Shape Memory ◽  
Electronic Devices ◽  
Shape Memory Polymers ◽  
Flexible Electronic ◽  
Flexible Electronic Devices

scholarly journals From Matrix Vesicles to Miniature Rocks: Evolution of Calcium Deposits in Calf Costochondral Junctions

Cartilage ◽  
2020 ◽  
pp. 194760352094122
Author(s):  
Jakub Jaroszewicz ◽  
Piotr Bazarnik ◽  
Anna Osiecka-Iwan ◽  
Anna Hyc ◽  
Emilia Choinska ◽  
...  
Keyword(s):  
Matrix Vesicles ◽  
Cartilage Matrix ◽  
X Ray Diffraction ◽  
3 Dimensional ◽  
Force Microscopy ◽  
Proliferative Zone ◽  
Atomic Force ◽  
Calcified Cartilage ◽  
Zone Of Provisional Calcification ◽  
Calcium Deposits

Objective Initial stages of cartilage matrix calcification depend on the activity of matrix vesicles. The purpose of the study was to describe how calcified matrix vesicles join into larger structures, to present their up-to-date undescribed 3-dimensional image, and to observe how calcified matrix relates to chondrocyte lacunae. Design Calcified cartilage was obtained from the zone of provisional calcification of calf costochondral junctions, then enzymatically isolated and studied by microtomography, scanning electron microscopy, atomic force microscopy and X-ray diffraction, and Fourier transform infrared spectroscopy. Results Hyaluronidase digestion released packets of granules surrounded by the cartilage matrix. Further digestion, with collagenase and trypsin, removed matrix and exposed granules with dimensions within 50 to 150 nm range, which we consider as equivalent of calcified matrix vesicles. Granules joined into larger groups with dimensions of 0.5 to 2 μm, which we call globular units. Certain matrix vesicles appeared well connected but contained globular units that had spaces filled with electron lucent material, presumably matrix or chondrocyte remnants. Globular units were organized into massive structures taking the shape of oval plates. Comparison of these plates with lacunae containing isogenous groups of chondrocytes from proliferative zone of costochondral junction suggests that the cells from a single lacuna were responsible for the formation of one plate. The plates were connected with each other and extended over provisional calcification zone. Conclusions The outcome showed how particular calcified matrix vesicles associate into globular units, which organize into massive structures assuming the shape of oval plates and eventually cover large areas of cartilage matrix.

scholarly journals 3D-printed cellular tips for tuning fork atomic force microscopy in shear mode

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Liangdong Sun ◽  
Hongcheng Gu ◽  
Xiaojiang Liu ◽  
Haibin Ni ◽  
Qiwei Li ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Shear Mode ◽  
Unique Contribution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Tips ◽  
3D Printed ◽  
Architectured Material ◽  
Energy Absorbing ◽  
Absorption Field

AbstractConventional atomic force microscopy (AFM) tips have remained largely unchanged in nanomachining processes, constituent materials, and microstructural constructions for decades, which limits the measurement performance based on force-sensing feedbacks. In order to save the scanning images from distortions due to excessive mechanical interactions in the intermittent shear-mode contact between scanning tips and sample, we propose the application of controlled microstructural architectured material to construct AFM tips by exploiting material-related energy-absorbing behavior in response to the tip–sample impact, leading to visual promotions of imaging quality. Evidenced by numerical analysis of compressive responses and practical scanning tests on various samples, the essential scanning functionality and the unique contribution of the cellular buffer layer to imaging optimization are strongly proved. This approach opens new avenues towards the specific applications of cellular solids in the energy-absorption field and sheds light on novel AFM studies based on 3D-printed tips possessing exotic properties.

ELECTROSPINNING OF CONTINUOUS CARBON NAONOFIBER-FILLED COMPOSITE FIBERS

2012 ◽  
Vol 05 ◽  
pp. 545-550
Author(s):  
Seyed Hamed Aboutalebi ◽  
Zahra Gholamvand ◽  
Mansoor Keyanpour-Rad
Keyword(s):  
Carbon Nanofibers ◽  
Polymer Fibers ◽  
Composite Fibers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Macro Scale ◽  
Electrospinning Method ◽  
Scale Structures ◽  
Filled Composite ◽  
Pan Fibers

In order to translate the superior properties of carbon nanofibers (CNFs) to macro-scale structures, an electrospinning route capable of placing CNFs into a continuous nano-scale composite fibril is introduced. In this work, composite fibers were produced by electrospinning solution of polyacrylonitrile ( PAN ) with carbon nanofibers dispersed in dimethylformamide ( DMF ), which is an effective solvent for carbon nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) demonstrated rough and globular surfaces on the CNF containing fibers. Raman spectra confirmed the presence of CNFs in the polymer fibers prepared employing the electrospinning method. Raman observation served as the direct evidence of successful filling of PAN fibers with CNFs and complemented the results obtained by SEM and AFM studies.

SELF-ASSEMBLED Ge-DOTS FOR Si SOLAR CELLS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4347-4351 ◽  
Author(s):  
H. PRESTING ◽  
J. KONLE ◽  
H. KIBBEL
Keyword(s):  
Solar Cells ◽  
Open Circuit Voltage ◽  
Elevated Temperatures ◽  
Growth Conditions ◽  
Open Circuit ◽  
3 Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
P Type

Silicon solar cells with embedded germanium (Ge) layers deposited as 3-dimensional islands in the Stranski-Krastanov growth mode have been grown by molecular beam epitaxy (MBE) to enhance the efficiency of Si thin film solar cells. The Ge-layers increase the infrared absorption in the base of the cell to achieve higher photocurrent which should overcome the loss in the open circuit voltage due to incorporation of a smaller bandgap material in the heterostructure. Up to 75 layers of Ge, each about 8 monolayers (ML) thick, separated by Si-spacer layers (9-18nm) have been deposited at rather elevated temperatures (700°C) on a standard 10Ωcm p-type Si-substrate. Island densities of 1011 cm -2 have been achieved by use of antimony (Sb) as surfactant. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to characterize the growth of Ge-islands under variuos growth conditions. Photocurrent measurements exhibit a higher photo-response in the infrared regime but a lower open circuit voltage of the fabricated solar cells compared to a Si-reference cell.

Numerical 3D-Simulation of Micromorph Silicon Thin Film Solar Cells

2011 ◽  
Vol 1321 ◽  
Author(s):  
Stefan Geißendörfer ◽  
Karsten von Maydell ◽  
Carsten Agert
Keyword(s):  
Solar Cells ◽  
Complex Refractive Index ◽  
Silicon Thin Film ◽  
3 Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Optical Generation ◽  
Surface Topographies ◽  
2D And 3D ◽  
Optical Generation Rate

ABSTRACTIn this contribution 1, 2 and 3-dimensional simulations of micromorph silicon solar cells are presented. In order to simulate solar cells with rough interfaces, the surface topographies were measured via atomic force microscopy (AFM) and transferred into the commercial software Sentaurus TCAD (Synopsys). The model of the structure includes layer thicknesses and optoelectronic parameters like complex refractive index and defect structure. Results of the space resolved optical generation rates by using of the optical solver Raytracer are presented. The space resolved optical generation rate inside the semiconductor layers depends on the structure of the transparent conductive oxides (TCO) interface. In this contribution the influence of different optical generation rates on the electrical characteristics of the solar cell device are investigated. Furthermore, the optical and electrical results of the 1D, 2D and 3D structures, which have equal layer thicknesses and optoelectronic parameters, are compared.

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