Direct-write assembly

Gratson CM, Garcia-Santamaria E, Lousse V, Xu M, Ean S, Lewis JA, Braun PV. (2006) Direct-write assembly of three-dimensional photonic crystals Conversion of polymer scaffolds to silicon hollow-woodpile structures. Adv Mater 18 461—465. 

Duoss EB, Twardowski M, Lewis J. (2007) Sol-gel inks for direct-write assembly of functional oxides. Adv Mater 19 4238-4243. 

Therriault, D., White, S.R., Lewis, J.A. Chaotic mixing in three-dimensional microvascular networks fabricated by direct-write assembly. Nat. Mater 2, 265-271... 

A. M. Dehormanh and M. N. Rahaman, Direct-write Assembly of Silicate and Borate Bioactive Glass Scaffolds for Bone Repair, J. Eur. Ceram. Soc., 32, 3637-46 (2012). 

GRA Gratson, G.M. and Lewis, J.A., Phase behavior and rheological properties of poly electrolyte inks for direct-write assembly, Langmuir, 21,457,2005. 

A direct-write assembly is a fabrication method that employs a controlled translation stage, which moves a pattern-generating device, for example, ink deposition nozzle, to create materials with controlled architecture and composition [4], Arbitrary 3D structures can be prepared by this method. For the pol3rmeric ink solidification occurs either upon deposition into a coagulating reservoir or UV exposure. This method can be characterized to be bioinspired because they copy a nature process - direct ink writing in the form of spider webs. 

Barry RA, Shepherd RE, Hanson JN, Nazzo RG, Wiltzius P, Lewis J. Direct-write assembly of 3D hydrogel scaffolds for guided cell growth. Adv Mater 2009 21 1-4. 

Figure 6.1 Direct-write assembly stage and imaging camera.

Representative examples of 3D lattices and radial arrays patterned by direct-write assembly are shown in Figure 6.3c and d. Thqr include arbitrary shapes, as solid or porous walls, spanning (rod-like) filaments, and tight- or broad-angled features, revealing the flexibility of this fabrication approach. Thq possess features that are nearly two orders of magnitude smaller than those attained by other multilayer ink printing techniques [2, 9]. 

The following sections of this chapter describe the design of different inks for the direct-write assembly of 3D microperiodic architectures composed of filamentary arrays, their rheological properties, and potential applications. Future... 

Figure 6.2 Schematic illustrations of direct-write assembly of 3D polymeric scaffolds deposited in (a) coagulating reservoir and (b) air and solidified in situ by UV curing. (Adapted with permission from [7] and [8]. Copyright (a) 2008 and (b) 2009 Wiley-VCH Verlag GmbH. Co. KCaA.)...

The ability to pattern 3D biocompatible scaffolds may lead to new fundamental understanding of tissue development and remodeling as well as the formation of multi-cellular aggregates in complex micro-environments that better mimic the targeted tissues of interest. Using direct-write assembly, 3D silk scaffolds for tissue... 

By comparison with other methods for preparing 3D tissue engineering scaffolds from degradable polymeric systems, our approach confers important benefits such as finer fiber diameter, avoidance ofharsh processing conditions of temperature or toxic organic solvents, and the ability to precisely control complex architectures. Direct-write assembly offers a unique path forward in support ofbiomaterial scaffolding for... 

Direct-write assembly has also been extended to other polymer systems, including those based on photocurable chemistries. When printing photopolymerizable... 

Direct-write assembly has been used to embed fully interconnected 3D microchannel network in an epoxy matrix. 3D scaffolds were fabricated with a fugitive organic ink using a robotic deposition apparatus in a layerwise scheme. As the presence of channels impacts the structural properties of the polymer, networks with maximum channel spacing and minimum channel diameter are desirable. Autonomic healing efficiency is evaluated on the basis of the ability of the healed polymer to recover fracture toughness. 

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