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https://www.readbyqxmd.com/read/29024044/4d-biofabrication-using-shape-morphing-hydrogels
#1
Alina Kirillova, Ridge Maxson, Georgi Stoychev, Cheryl T Gomillion, Leonid Ionov
Despite the tremendous potential of bioprinting techniques toward the fabrication of highly complex biological structures and the flourishing progress in 3D bioprinting, the most critical challenge of the current approaches is the printing of hollow tubular structures. In this work, an advanced 4D biofabrication approach, based on printing of shape-morphing biopolymer hydrogels, is developed for the fabrication of hollow self-folding tubes with unprecedented control over their diameters and architectures at high resolution...
October 12, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28967260/four-dimensional-printing-of-liquid-crystal-elastomers
#2
Cedric P Ambulo, Julia J Burroughs, Jennifer M Boothby, Hyun Kim, M Ravi Shankar, Taylor H Ware
Three-dimensional structures capable of reversible changes in shape, i.e., four-dimensional-printed structures, may enable new generations of soft robotics, implantable medical devices, and consumer products. Here, thermally responsive liquid crystal elastomers (LCEs) are direct-write printed into 3D structures with a controlled molecular order. Molecular order is locally programmed by controlling the print path used to build the 3D object, and this order controls the stimulus response. Each aligned LCE filament undergoes 40% reversible contraction along the print direction on heating...
October 11, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28961100/an-mri-compatible-hydrodynamic-simulator-of-cerebrospinal-fluid-motion-in-the-cervical-spine
#3
Suraj Thyagaraj, Soroush H Pahlavian, Lucas R Sass, Francis Loth, Morteza Vatani, Jao-Won Choi, R Shane Tubbs, Daniel Giese, Jan-Robert Kroger, Alexander C Bunck, Bryn A Martin
GOAL: Develop and test an MRI-compatible hydrodynamic simulator of cerebrospinal fluid (CSF) motion in the cervical spinal subarachnoid space. Four anatomically realistic subject-specific models were created based on a 22-year-old healthy volunteer and a five-year-old patient diagnosed with Chiari I malformation. METHODS: The in vitro models were based on manual segmentation of high-resolution T2-weighted MRI of the cervical spine. Anatomically realistic dorsal and ventral spinal cord nerve rootlets (NR) were added...
September 26, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28877531/towards-individualized-tracheobronchial-stents-technical-practical-and-legal-considerations
#4
Lutz Freitag, Martin Gördes, Paul Zarogoulidis, Kaid Darwiche, Daniel Franzen, Faustina Funke, Wolfgang Hohenforst-Schmidt, Hervé Dutau
Stent placement has been established as a standard procedure for treating airway obstructions. Other indications are localized malacias and fistulas. Though many different stents with various diameters and lengths are available, the shapes are hardly ever ideal because of the distorted anatomy in patients with diseased airways. There are technical and legal limitations for customizing purchased airway stents. Individually tailored stents would be preferable. New techniques of additive manufacturing such as 3D printing make it possible to produce optimized stents for a particular patient...
2017: Respiration; International Review of Thoracic Diseases
https://www.readbyqxmd.com/read/28771375/recent-development-and-biomedical-applications-of-self-healing-hydrogels
#5
Yinan Wang, Christian K Adokoh, Ravin Narain
Hydrogels are of special importance, owing to their high-water content and various applications in biomedical and bio-engineering research. Self-healing properties is a common phenomenon in living organisms. Their endowed property of being able to self-repair after physical/chemical/mechanical damage to fully or partially its original properties demonstrates their prospective therapeutic applications. Due to complicated preparation and selection of suitable materials, the application of many host-guest supramolecular polymeric hydrogels are so limited...
August 3, 2017: Expert Opinion on Drug Delivery
https://www.readbyqxmd.com/read/28766726/a-novel-3d-printed-phantom-insert-for-4d-pet-ct-imaging-and-simultaneous-integrated-boost-radiotherapy
#6
Laura Cerviño, Dima Soultan, Mariel Cornell, Adam Yock, Niclas Pettersson, William Y Song, Joseph Aguilera, Sunil Advani, James Murphy, Carl Hoh, Claude James, Anthony Paravati, Robin Coope, Bradford Gill, Vitali Moiseenko
PURPOSE: To construct a 3D-printed phantom insert designed to mimic the variable PET tracer uptake seen in lung tumor volumes and a matching dosimetric insert to be used in simultaneous integrated boost (SIB) phantom studies, and to evaluate the design through end-to-end tests. METHODS: A set of phantom inserts was designed and manufactured for a realistic representation of gated radiotherapy steps from 4D PET/CT scanning to dose delivery. A cylindrical phantom (φ80 × 120 mm) holds inserts for PET/CT scanning...
October 2017: Medical Physics
https://www.readbyqxmd.com/read/28759164/4d-origami-by-smart-embroidery
#7
Georgi Stoychev, Mir Jalil Razavi, Xianqiao Wang, Leonid Ionov
There exist many methods for processing of materials: extrusion, injection molding, fibers spinning, 3D printing, to name a few. In most cases, materials with a static, fixed shape are produced. However, numerous advanced applications require customized elements with reconfigurable shape. The few available techniques capable of overcoming this problem are expensive and/or time-consuming. Here, the use of one of the most ancient technologies for structuring, embroidering, is proposed to generate sophisticated patterns of active materials, and, in this way, to achieve complex actuation...
July 31, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28726680/towards-4d-printed-scaffolds-for-tissue-engineering-exploiting-3d-shape-memory-polymers-to-deliver-time-controlled-stimulus-on-cultured-cells
#8
Wilhelmus J Hendrikson, Jeroen Rouwkema, Federico Clementi, Clemens A van Blitterswijk, Silvia Farè, Lorenzo Moroni
Tissue engineering needs innovative solutions to better fit the requirements of a minimally invasive approach, providing at the same time instructive cues to cells. The use of shape memory polyurethane has been investigated by producing 4D scaffolds via additive manufacturing technology. Scaffolds with two different pore network configurations (0/90° and 0/45°) were characterized by dynamic-mechanical analysis. The thermo-mechanical analysis showed a Tg at about 32 °C (Tg = T trans), indicating no influence of the fabrication process on the transition temperature...
August 2, 2017: Biofabrication
https://www.readbyqxmd.com/read/28624566/four-dimensional-phase-contrast-magnetic-resonance-imaging-protocol-optimization-using-patient-specific-3-dimensional-printed-replicas-for-in%C3%A2-vivo-imaging-before-and-after-flow-diverter-placement
#9
Christof Karmonik, Jeff R Anderson, Saba Elias, Richard Klucznik, Orlando Diaz, Yi Jonathan Zhang, Robert G Grossman, Gavin W Britz
OBJECTIVE: Hemodynamics in cerebral aneurysms are currently investigated toward clinical efficacy using nonstandardized computational simulation techniques. At the same time, flow patterns and velocities are accessible by 4-dimensional phase contrast magnetic resonance imaging (4D pcMRI). Complexity of protocol design and imaging duration has limited the use of this technique in clinical imaging. A new approach is presented to overcome these limitations. METHODS: Three-dimensional (3D) replicas of 2 cerebral aneurysms were fabricated by fused deposition prototyping (3D printing) and imaged using 4D pcMRI while connected to a magnetic resonance imaging-compatible continuous flow loop...
September 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28546911/graphene-based-polymer-bilayers-with-superior-light-driven-properties-for-remote-construction-of-3d-structures
#10
Zhenhua Tang, Ziwei Gao, Shuhai Jia, Fei Wang, Yonglin Wang
3D structure assembly in advanced functional materials is important for many areas of technology. Here, a new strategy exploits IR light-driven bilayer polymeric composites for autonomic origami assembly of 3D structures. The bilayer sheet comprises a passive layer of poly(dimethylsiloxane) (PDMS) and an active layer comprising reduced graphene oxides (RGOs), thermally expanding microspheres (TEMs), and PDMS. The corresponding fabrication method is versatile and simple. Owing to the large volume expansion of the TEMs, the two layers exhibit large differences in their coefficients of thermal expansion...
May 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
https://www.readbyqxmd.com/read/28439560/direct-4d-printing-via-active-composite-materials
#11
Zhen Ding, Chao Yuan, Xirui Peng, Tiejun Wang, H Jerry Qi, Martin L Dunn
We describe an approach to print composite polymers in high-resolution three-dimensional (3D) architectures that can be rapidly transformed to a new permanent configuration directly by heating. The permanent shape of a component results from the programmed time evolution of the printed shape upon heating via the design of the architecture and process parameters of a composite consisting of a glassy shape memory polymer and an elastomer that is programmed with a built-in compressive strain during photopolymerization...
April 2017: Science Advances
https://www.readbyqxmd.com/read/28429796/spatial-control-of-functional-response-in-4d-printed-active-metallic-structures
#12
Ji Ma, Brian Franco, Gustavo Tapia, Kubra Karayagiz, Luke Johnson, Jun Liu, Raymundo Arroyave, Ibrahim Karaman, Alaa Elwany
We demonstrate a method to achieve local control of 3-dimensional thermal history in a metallic alloy, which resulted in designed spatial variations in its functional response. A nickel-titanium shape memory alloy part was created with multiple shape-recovery stages activated at different temperatures using the selective laser melting technique. The multi-stage transformation originates from differences in thermal history, and thus the precipitate structure, at various locations created from controlled variations in the hatch distance within the same part...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28242061/patient-specific-in-vitro-models-for-hemodynamic-analysis-of-congenital-heart-disease-additive-manufacturing-approach
#13
Rafael Medero, Sylvana García-Rodríguez, Christopher J François, Alejandro Roldán-Alzate
Non-invasive hemodynamic assessment of total cavopulmonary connection (TCPC) is challenging due to the complex anatomy. Additive manufacturing (AM) is a suitable alternative for creating patient-specific in vitro models for flow measurements using four-dimensional (4D) Flow MRI. These in vitro systems have the potential to serve as validation for computational fluid dynamics (CFD), simulating different physiological conditions. This study investigated three different AM technologies, stereolithography (SLA), selective laser sintering (SLS) and fused deposition modeling (FDM), to determine differences in hemodynamics when measuring flow using 4D Flow MRI...
March 21, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28195832/four-dimensional-printing-hierarchy-scaffolds-with-highly-biocompatible-smart-polymers-for-tissue-engineering-applications
#14
Shida Miao, Wei Zhu, Nathan J Castro, Jinsong Leng, Lijie Grace Zhang
The objective of this study was to four-dimensional (4D) print novel biomimetic gradient tissue scaffolds with highly biocompatible naturally derived smart polymers. The term "4D printing" refers to the inherent smart shape transformation of fabricated constructs when implanted minimally invasively for seamless and dynamic integration. For this purpose, a series of novel shape memory polymers with excellent biocompatibility and tunable shape changing effects were synthesized and cured in the presence of three-dimensional printed sacrificial molds, which were subsequently dissolved to create controllable and graded porosity within the scaffold...
October 2016: Tissue Engineering. Part C, Methods
https://www.readbyqxmd.com/read/28048927/mo-fg-bra-05-dosimetric-and-radiobiological-validation-of-respiratory-gating-in-conventional-and-hypofractionated-radiotherapy-of-the-lung-effect-of-dose-dose-rate-gating-window-and-breathing-pattern
#15
L Cervino, D Soultan, N Pettersson, A Yock, M Cornell, J Aguilera, J Murphy, B Gill, S Advani, V Moiseenko
PURPOSE: to evaluate the dosimetric and radiobiological consequences from having different gating windows, dose rates, and breathing patterns in gated VMAT lung radiotherapy. METHODS: A novel 3D-printed moving phantom with central high and peripheral low tracer uptake regions was 4D FDG-PET/CT-scanned using ideal, patient-specific regular, and irregular breathing patterns. A scan of the stationary phantom was obtained as a reference. Target volumes corresponding to different uptake regions were delineated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047932/tu-h-campus-iep3-02-neurovascular-4d-parametric-imaging-using-co-registration-of-biplane-dsa-sequences-with-3d-vascular-geometry-obtained-from-cone-beam-ct
#16
A Balasubramoniam, D Bednarek, S Rudin, C Ionita
PURPOSE: To create 4D parametric images using biplane Digital Subtraction Angiography (DSA) sequences co-registered with the 3D vascular geometry obtained from Cone Beam-CT (CBCT). METHODS: We investigated a method to derive multiple 4D Parametric Imaging (PI) maps using only one CBCT acquisition. During this procedure a 3D-DSA geometry is stored and used subsequently for all 4D images. Each time a biplane DSA is acquired, we calculate 2D parametric maps of Bolus Arrival Time (BAT), Mean Transit Time (MTT) and Time to Peak (TTP)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28009155/three-dimensional-printing-of-shape-memory-composites-with-epoxy-acrylate-hybrid-photopolymer
#17
Ran Yu, Xin Yang, Ying Zhang, Xiaojuan Zhao, Xiao Wu, Tingting Zhao, Yulei Zhao, Wei Huang
Four-dimensional printing, a new process to fabricate active materials through three-dimensional (3D) printing developed by MIT's Self-Assembly Lab in 2014, has attracted more and more research and development interests recently. In this paper, a type of epoxy-acrylate hybrid photopolymer was synthesized and applied to fabricate shape memory polymers through a stereolithography 3D printing technique. The glass-to-rubbery modulus ratio of the printed sample determined by dynamic mechanical analysis is as high as 600, indicating that it may possess good shape memory properties...
January 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27997104/direct-write-fabrication-of-4d-active-shape-changing-structures-based-on-a-shape-memory-polymer-and-its-nanocomposite
#18
Hongqiu Wei, Qiwei Zhang, Yongtao Yao, Liwu Liu, Yanju Liu, Jinsong Leng
Four-dimensional (4D) active shape-changing structures based on shape memory polymers (SMPs) and shape memory nanocomposites (SMNCs) are able to be controlled in both space and time and have attracted increasing attention worldwide. However, conventional processing approaches have restricted the design space of such smart structures. Herein, 4D active shape-changing architectures in custom-defined geometries exhibiting thermally and remotely actuated behaviors are achieved by direct-write printing of ultraviolet (UV) cross-linking poly(lactic acid)-based inks...
December 20, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27936286/ultrafast-digital-printing-toward-4d-shape-changing-materials
#19
Limei Huang, Ruiqi Jiang, Jingjun Wu, Jizhou Song, Hao Bai, Bogeng Li, Qian Zhao, Tao Xie
Ultrafast 4D printing (<30 s) of responsive polymers is reported. Visible light triggered polymerization of commercial monomers defines digitally stress distribution in a 2D polymer film. Releasing the stress after the printing converts the structure into 3D. An additional dimension can be incorporated by choosing the printing precursors. The process overcomes the speed limiting steps of typical 3D (4D) printing.
December 9, 2016: Advanced Materials
https://www.readbyqxmd.com/read/27918636/4d-printing-of-shape-memory-based-personalized-endoluminal-medical-devices
#20
Matt Zarek, Nicola Mansour, Shir Shapira, Daniel Cohn
The convergence of additive manufacturing and shape-morphing materials is promising for the advancement of personalized medical devices. The capability to transform 3D objects from one shape to another, right off the print bed, is known as 4D printing. Shape memory thermosets can be tailored to have a range of thermomechanical properties favorable to medical devices, but processing them is a challenge because they are insoluble and do not flow at any temperature. This study presents here a strategy to capitalize on a series of medical imaging modalities to construct a printable shape memory endoluminal device, exemplified by a tracheal stent...
January 2017: Macromolecular Rapid Communications
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