Architecting graphene oxide rolled-up micromotors : a simple paper-based manufacturing technology

A graphene oxide rolled-up tube production process is reported using wax-printed membranes for the fabrication of on-demand engineered micromotors at different levels of oxidation, thickness, and lateral dimensions. The resultant graphene oxide rolled-up tubes can show magnetic and catalytic movement within the addition of magnetic nanoparticles or sputtered platinum in the surface of graphene-oxide-modified wax-printed membranes prior to the scrolling process. As a proof of concept, the as-prepared catalytic graphene oxide rolled-up micromotors are successfully exploited for oil removal from water. This micromotor production technology relies on an easy, operator-friendly, fast, and cost-efficient wax-printed paper-based method and may offer a myriad of hybrid devices and applications

Multimaterial 4D Printing with Tailorable Shape Memory Polymers

We present a new 4D printing approach that can create high resolution (up to a few microns), multimaterial shape memory polymer (SMP) architectures. The approach is based on high resolution projection microstereolithography (PμSL) and uses a family of photo-curable methacrylate based copolymer networks. We designed the constituents and compositions to exhibit desired thermomechanical behavior (including rubbery modulus, glass transition temperature and failure strain which is more than 300% and larger than any existing printable materials) to enable controlled shape memory behavior. We used a high resolution, high contrast digital micro display to ensure high resolution of photo-curing methacrylate based SMPs that requires higher exposure energy than more common acrylate based polymers. An automated material exchange process enables the manufacture of 3D composite architectures from multiple photo-curable SMPs. In order to understand the behavior of the 3D composite microarchitectures, we carry out high fidelity computational simulations of their complex nonlinear, time-dependent behavior and study important design considerations including local deformation, shape fixity and free recovery rate. Simulations are in good agreement with experiments for a series of single and multimaterial components and can be used to facilitate the design of SMP 3D structures

Future of additive manufacturing: Overview of 4D and 3D printed smart and advanced materials and their applications

© 2020 Elsevier B.V. 4D printing is an emerging field in additive manufacturing of time responsive programmable materials. The combination of 3D printing technologies with materials that can transform and possess shape memory and self-healing capabilities means the potential to manufacture dynamic structures readily for a myriad of applications. The benefits of using multifunctional materials in 4D printing create opportunities for solutions in demanding environments including outer space, and extreme weather conditions where human intervention is not possible. The current progress of 4D printable smart materials and their stimuli-responsive capabilities are overviewed in this paper, including the discussion of shape-memory materials, metamaterials, and self-healing materials and their responses to thermal, pH, moisture, light, magnetic and electrical exposures. Potential applications of such systems have been explored to include advancements in health monitoring, electrical devices, deployable structures, soft robotics and tuneable metamaterials

Morphing in nature and beyond: a review of natural and synthetic shape-changing materials and mechanisms

Shape-changing materials open an entirely new solution space for a wide range of disciplines: from architecture that responds to the environment and medical devices that unpack inside the body, to passive sensors and novel robotic actuators. While synthetic shape-changing materials are still in their infancy, studies of biological morphing materials have revealed key paradigms and features which underlie efficient natural shape-change. Here, we review some of these insights and how they have been, or may be, translated to artificial solutions. We focus on soft matter due to its prevalence in nature, compatibility with users and potential for novel design. Initially, we review examples of natural shape-changing materials—skeletal muscle, tendons and plant tissues—and compare with synthetic examples with similar methods of operation. Stimuli to motion are outlined in general principle, with examples of their use and potential in manufactured systems. Anisotropy is identified as a crucial element in directing shape-change to fulfil designed tasks, and some manufacturing routes to its achievement are highlighted. We conclude with potential directions for future work, including the simultaneous development of materials and manufacturing techniques and the hierarchical combination of effects at multiple length scales.</p

Biomimetic 4D Printing

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. 4D printing is an emerging approach in which 3D objects are produced whose shape changes over time. 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. My Ph.D. thesis focuses on a new 4D printing method, which is inspired by the movements or natural plants. Specifically, we encode swelling and elastic anisotropy in printed hydrogel composites through the alignment of stiff cellulose fibrils on-the-fly during printing. 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. 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. 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. 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. 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. Our filled hydrogel ink is modular, allowing a broad range of hydrogel chemistries and anisotropic filler compositions to be explored. For example, both reversible and non-reversible hydrogels were explored; namely poly(N-isopropyl acrylamide) (PNIPAm) and poly(N,N-dimethylacrylamide) (PDMAm), respectively. Additionally, light-absorbing carbon microfibers were incorporated to demonstrate reversible, multi-stimuli responsive 4D printing. 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. 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. These biocompatible shape-shifting architectures with interesting mechanical and photothermal properties may find applications in smart textiles, tissue microgrippers or scaffolds, or as actuators and sensors in soft machines.Engineering and Applied Sciences - Engineering Science

Ultra personalization and textile thinking in interaction design

\u3cp\u3eTextile Thinking and Ultra Personalization are guiding the PhD research in wearable on body sensing in the creation of garments / accessories. Textile Thinking involves the superficial surface of a design process that attempts to create a point of view to reach new understandings in design and architecture. When applied to interaction design in the near field the garments that people wear can become an interface or expression for sensing and actuating. Specific ideas such as Fit are explored to aid in developing a more unique understanding of interaction on the body.\u3c/p\u3

Mechanics of biomimetic 4D printed structures

© 2018 The Royal Society of Chemistry. Recent progress in additive manufacturing and materials engineering has led to a surge of interest in shape-changing plate and shell-like structures. Such structures are typically printed in a planar configuration and, when exposed to an ambient stimulus such as heat or humidity, swell into a desired three-dimensional geometry. Viewed through the lens of differential geometry and elasticity, the application of the physical stimulus can be understood as a local change in the metric of a two dimensional surface embedded in three dimensions. To relieve the resulting elastic frustration, the structure will generally bend and buckle out-of-plane. Here, we propose a numerical approach to convert the discrete geometry of filament bilayers, associated with print paths of inks with given material properties, into continuous plates with inhomogeneous growth patterns and thicknesses. When subject to prescribed growth anisotropies, we can then follow the evolution of the shapes into their final form. We show that our results provide a good correspondence between experiments and simulations, and lead to a framework for the prediction and design of shape-changing structures

3D Bioprinting of Vascularized, Heterogeneous Cell-Laden Tissue Constructs

A new bioprinting method is reported for fabricating 3D tissue constructs replete with vasculature, multiple types of cells, and extracellular matrix. These intricate, heterogeneous structures are created by precisely co-printing multiple materials, known as bioinks, in three dimensions. These 3D micro-engineered environments open new ­avenues for drug screening and fundamental studies of wound healing, angiogenesis, and stem-cell niches.Engineering and Applied Science