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Despite significant advances in synthetic biology at industrial scales, digital fabrication challenges have, to date, precluded its implementation at the product scale. We present, Mushtari, a multimaterial 3D printed fluidic wearable designed to culture microbial communities. Thereby we introduce a computational design environment for additive manufacturing of geometrically complex and materially heterogeneous fluidic channels. We demonstrate how controlled variation of geometrical and optical properties at high spatial resolution can be achieved through a combination of computational growth modeling and multimaterial bitmap printing. Furthermore, we present the implementation, characterization, and evaluation of support methods for creating product-scale fluidics. Finally, we explore the cytotoxicity of 3D printed materials in culture studies with the model microorganisms, Escherichia coli and Bacillus subtilis. The results point toward design possibilities that lie at the intersection of computational design, additive manufacturing, and synthetic biology, with the ultimate goal of imparting biological functionality to 3D printed products.

L'invention concerne un systeme qui comprend une imprimante (3D) tridimensionnelle, un processeur configure pour calculer des donnees d'objet en vue d'imprimer l'objet, et un organe de commande. Les donnees d'objet sont definies par couches, et les donnees d'objet d'une couche definissent une distribution selective par rapport a des distances differentes. L'organe de commande est configure pour commander la distribution du materiau de construction par couches sur la base des donnees d'objet. L'impression comprend une unite de distribution qui sert a distribuer selectivement un materiau de construction par couches afin de construire l'objet, et un plateau de construction qui sert a supporter le materiau distribue pour construire l'objet. L'impression consiste en outre a utiliser une structure de support prefabriquee, et a imprimer au moins une partie de l'objet sur la structure de support prefabriquee.

We present a bitmap printing method and digital workflow using multi-material high resolution Additive Manufacturing (AM). Material composition is defined based on voxel resolution and used to fabricate a design object with locally varying material stiffness, aiming to satisfy the design objective. In this workflow voxel resolution is set by the printer's native resolution, eliminating the need for slicing and path planning. Controlling geometry and material property variation at the resolution of the printer provides significantly greater control over structure property function relationships. To demonstrate the utility of the bitmap printing approach we apply it to the design of a customized prosthetic socket. Pressure-sensing elements are concurrently fabricated with the socket, providing possibilities for evaluation of the socket's fit. The level of control demonstrated in this study cannot be achieved using traditional CAD tools and volume-based AM workflows, implying that new CAD workflows must be developed in order to enable designers to harvest the capabilities of AM. (C) 2014 Elsevier Ltd. All rights reserved.

We propose a new design of complex self-evolving structures that vary over time due to environmental interaction. In conventional 3D printing systems, materials are meant to be stable rather than active and fabricated models are designed and printed as static objects. Here, we introduce a novel approach for simulating and fabricating self-evolving structures that transform into a predetermined shape, changing property and function after fabrication. The new locally coordinated bending primitives combine into a single system, allowing for a global deformation which can stretch, fold and bend given environmental stimulus.

Abstract Gemini is a chaise lounge constructed using hybrid fabrication involving 3D printing of a textured polymeric skin combined with CNC milling of a wooden chassis. The texture of the chaise was inspired by the seed geometry of the Ornithogalum dubium flower and designed using a computational implementation of an inhomogeneous Poisson process. The 3D-printed texture was informed by the weight distribution of a person with the goal of delivering structural support and comfort on the one hand and maximizing the absorption of sound emanating from exterior sources of noise on the other. Gemini is the first functional object produced using the Stratasys Objet500 Connex3 color multimaterial 3D printer including the Tango+ soft material. It represents one of the first cases of a hybrid additive–subtractive manufacturing approach, which combines the strength of both of these techniques.

3D printing has captured the imagination of everyone from industry experts to at-home hobbyists.However, there are significant challenges that need to be addressed in order for 3D printing to have widespread adoption in construction and manufacturing.A new category of printing has recently been introduced, called 4D printing, which describes the ability for a material system or object to change form and/or function after printing.4D printing offers a number of unique advantages over 3D printing that may prove to be the critical capability needed to catalyze widespread implementation.This paper attempts to go beyond existing capabilities in 4D printing to create precise and universal folding techniques that approach a wider range of applications through a series of radically new physical models.A number of physical and digital prototypes demonstrate major advances in 4D printing, including: custom angle-structures that can transform from any one shape into another rigid 3D structure, curved-crease origami for doubly curved surfaces and dynamic fields utilizing surface curling and gradient material distribution.

Bioprinting in tissue engineering applies 3D printing technologies towards the development of precisely designed scaffolds for tissue repair and organ replacement. The printed scaffolds may incorporate polymeric constituents together with biological payloads, including cells and biochemically active additives. The scaffolds can be designed with spatial precision, achieving both biochemical and biophysical heterogeneity that mimic the extracellular environment of the body's tissues. Recent advances in 3D bioprinting have applied a strategy of controlling physical properties together with bioactivity to influence specific interactions with cellular systems, including spatial and temporal patterns of biochemical and biomechanical cues that regulate cell behavior and improve tissue integration. Important new advances in tissue engineering have now been realized based on these approaches, and clinical applications for printed scaffolds continue to drive further improvements to 3D bioprinter technologies.

We develop a biomaterial based on protein-polymer conjugates where poly(ethylene glycol) (PEG) polymer chains are covalently linked to multiple thiols on denatured fibrinogen. We hypothesize that conjugation of large diacrylate-functionalized linear PEG chains to fibrinogen could govern the molecular architecture of the polymer network via a unique protein polymer interaction. The hypothesis is explored using carefully designed shear rheometry and swelling experiments of the hydrogels and their precursor PEG/fibrinogen conjugate solutions. The physical properties of non-cross-linked and UV cross-linked PEGylated fibrinogen having PEG molecular weights ranging from 10 to 20 kDa are specifically investigated. Attaching multiple hydrophilic, functionalized PEG chains to the denatured fibrinogen solubilizes the denatured protein and enables a rapid free-radical polymerization cross-linking reaction in the hydrogel precursor solution. As expected, the conjugated protein-polymer macromolecular complexes act to mediate the interactions between radicals and unsaturated bonds during the free-radical polymerization reaction, when compared to control PEG hydrogels. Accordingly, the cross-linking kinetics and stiffness of the cross-linked hydrogel are highly influenced by the protein polymer conjugate architecture and molecular entanglements arising from hydrophobic/hydrophilic interactions and steric hindrances. The proteolytic degradation products of the protein-polymer conjugates proves to be were different from those of the non-conjugated denatured protein degradation products, indicating that steric hindrances may alter the proteolytic susceptibility of the PEG-protein adduct. A more complete understanding of the molecular complexities associated with this type of protein-polymer conjugation can help to identify the full potential of a biomaterial that combines the advantages of synthetic polymers and bioactive proteins.

Recent studies have identified extracellular matrix (ECM) compliance as an influential factor in determining the fate of anchorage-dependent cells. We explore a method of examining the influence of ECM compliance on cell morphology and remodeling in three-dimensional culture. For this purpose, a biological ECM analog material was developed to pseudo-independently alter its biochemical and physical properties. A set of 18 material variants were prepared with shear modulus ranging from 10 to 700 Pa. Smooth muscle cells were encapsulated in these materials and time-lapse video microscopy was used to show a relationship between matrix modulus, proteolytic biodegradation, cell spreading, and cell compaction of the matrix. The proteolytic susceptibility of the matrix, the degree of matrix compaction, and the cell morphology were quantified for each of the material variants to correlate with the modulus data. The initial cell spreading into the hydrogel matrix was dependent on the proteolytic susceptibility of the materials, whereas the extent of cell compaction proved to be more correlated to the modulus of the material. Inhibition of matrix metalloproteinases profoundly affected initial cell spreading and remodeling even in the most compliant materials. We concluded that smooth muscle cells use proteolysis to form lamellipodia and tractional forces to contract and remodel their surrounding microenvironment. Matrix modulus can therefore be used to control the extent of cellular remodeling and compaction. This study further shows that the interconnection between matrix modulus and proteolytic resistance in the ECM may be partly uncoupled to provide insight into how cells interpret their physical three-dimensional microenvironment.

Our research is focused on the design of engineered biomaterials that can harness natural cellular and molecular healing pathways to enhance functional tissue regeneration. Two important considerations for tissue regeneration are induction and remodeling. Although the healing process that leads to functional regeneration relies on numerous biological events, it can often be catalyzed and sustained by a single inductive biological factor. Ideally, one can engineer a synthetic biomaterial to possess inductive healing properties using protein immobilization techniques and also to be susceptible to cell-mediated remodeling. Toward this goal, we developed a novel biomimetic material that can harness the inductive properties of the natural blood clot protein fibrinogen. Using synthetic polymer conjugation chemistry, we modify the fibrinogen molecule with poly(ethylene glycol) (PEG) to create a biosynthetic precursor with tunable physicochemical properties based on the molecular relationship between the two constituents [1]. A hydrogel matrix is formed from the biocompatible liquid precursor by non-toxic free-radical polymerization using light activation (photopolymerization). The susceptibility of this hydrogel biomaterial to protease degradation and consequent cell-mediated remodeling is precisely controlled by the amount and size of the PEG constituent in the polymer network [4]. The protein-based material also conveys inductive signals to cells through bioactive sites on the fibrinogen backbone. This biomimetic material has been tested in cell-based tissue engineering applications and in acellular in vivo tissue regeneration applications with bone [7], cartilage [2,9], and cardiac tissues [11,12]. In cardiac cell therapy for example, the inability to locally deliver and retain cell grafts in the damaged cardiac muscle has limited the effectiveness of this important treatment option. As cardiac stem cell research addresses the issue of cell sourcing, there is still a need for biomaterials that can effectively deliver the cell grafts into the infarct region and promote structural and functional integration with the native myocardium, without damaging the cells or the heart muscle [3]. Injectable hydrogel biomaterials based on hydrophilic, biocompatible polymers are an optimal delivery system for cardiac tissue engineering [6]; the high water content of these polymers creates a tissue-like environment, and in situ polymerization provides a means of injection and gelation of a cell suspension polymer mixture directly in the site of the infarct [8]. In the current investigation, we explore the use PEGylated fibrinogen polymer hydrogels for myocardial tissue engineering. The optimization of hydrogel composition and cell seeding density were assessed