![]() ![]() ![]() In summary, this biomimetic 4D printing platform enables the design and fabrication of complex, reversible shape changing architectures printed with one composite hydrogel ink in a single step. In this case, reversible shape changes were encoded via 4D printing and then triggered either by heating PNIPAm or illuminating the printed architectures with a near IR laser. Additionally, light-absorbing carbon microfibers were incorporated to demonstrate reversible, multi-stimuli responsive 4D printing. For example, both reversible and non-reversible hydrogels were explored namely poly(N-isopropyl acrylamide) (PNIPAm) and poly(N,N-dimethylacrylamide) (PDMAm), respectively. Our filled hydrogel ink is modular, allowing a broad range of hydrogel chemistries and anisotropic filler compositions to be explored. With collaborators, a model has been developed for solving both the forward and inverse design problems, based on an adaptation of the classic Timoshenko bending theory, allowing us to create nearly arbitrary structures. We have demonstrated the ability to precisely control curvature by varying the actual and the effective thickness, the latter of which is governed by the interfilament spacing within the printed architectures. We have demonstrated complex changes in curvature including bending, twisting, ruffling, conical defects, and more, all using a single hydrogel-based ink printed in a single step. When structures are patterned with broken-symmetry, i.e., as bilayers, their anisotropic swelling leads to programmable out-of-plane deformation, determined by the orientation of printed filaments. Filler alignment parallel to the print path leads to enhanced stiffness in that direction hence, upon immersion in water, the printed filaments expand preferentially in the direction orthogonal to the printing path. Specifically, we encode swelling and elastic anisotropy in printed hydrogel composites through the alignment of stiff cellulose fibrils on-the-fly during printing. ![]() thesis focuses on a new 4D printing method, which is inspired by the movements or natural plants. Initial demonstrations have relied on commercial 3D printers and proprietary materials, which limits both the tunability and mechanisms that can be incorporated into the printed architectures. 4D printing is an emerging approach in which 3D objects are produced whose shape changes over time. This journal is © The Royal Society of Chemistry.Abstract Advances in the design of adaptive matter capable of programmable, environmentally-responsive changes in shape would enable myriad applications including smart textiles, scaffolds for tissue engineering, and smart machines. The future applications would be based on these smart and intelligent materials thus, it is important to modify the existing voxel-based modeling and simulation approach and discuss efficient printing methods to fabricate such bio-inspired materials. This paper also outlines a review of the 4D printing of (a) smart photocurable and biocompatible scaffolds with renewable plant oils, which can be a better alternative to traditional polyethylene glycol diacrylate (PEGDA) to support human bone marrow mesenchymal stem cells (hMSCs), and (b) a biomimetic dual shape-changing tube having applications in biomedical engineering as a bioimplant. Such plant-inspired architectures can change shapes when immersed in water. The shape-changing materials are inspired from biological objects, such as flowers, which are temperature-sensitive or touch-sensitive, and can be 4D printed in such a way that they are encrypted with a decentralized, anisotropic enlargement feature under a restrained alignment of cellulose fibers as in the case of composite hydrogels. ![]() The voxel-based modeling and simulation approach is further modified using bi-exponential expressions to encode the time-dependent behavior of the bio-inspired 4D printed materials. The voxel-based modeling and simulation approach has the enhanced features for the rapid testing (prior to moving into design procedures) of the given distribution of such 4D printed smart materials (SMs) while checking for behaviors, particularly when these intelligent materials are exposed to a stimulus. This paper encompasses two recent approaches to explore the conceptual design of 4D printed objects in detail: (a) an application-based modeling and simulation approach for phytomimetic structures and (b) a voxel-based modeling and simulation approach. For this, the designing space has to be explored in the initial stages, which is lagging so far. However, the manufacturing of such objects is still a challenging task. The 4D printed materials are stimulus-responsive and have shape-changing features. 4D printed objects are indexed under additive manufacturing (AM) objects. ![]()
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