Origami by frontal photopolymerization

Zhao, Zeang; Wu, Jiangtao; Mu, Xiaoming; Chen, Haosen; Hu, Qi; Fang, Daining

doi:10.1126/sciadv.1602326

Cited by 203 publications

(182 citation statements)

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“…Traditional manufacturing methods for assembling origami structures mainly rely on manual or machine‐assisted folding, which is challenging to implement on small scales and advanced materials . Self‐folding ranging from nanoscale to microscale and macroscale of various materials including metals, semiconductors, and polymers have been achieved by self‐actuating materials (e.g., shape memory materials), or using stimuli‐active hinges (e.g., by heat, light, or electricity), capillary forces, or residual stresses in the thin film. Figure c illustrates the process of self‐folding Al 2 O 3 facets with Au patterns.…”

Section: Structural Designs For Soft Electronicsmentioning

confidence: 99%

Materials and Structures toward Soft Electronics

et al. 2018

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Soft electronics are intensively studied as the integration of electronics with dynamic nonplanar surfaces has become necessary. Here, a discussion of the strategies in materials innovation and structural design to build soft electronic devices and systems is provided. For each strategy, the presentation focuses on the fundamental materials science and mechanics, and example device applications are highlighted where possible. Finally, perspectives on the key challenges and future directions of this field are presented.

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Section: Structural Designs For Soft Electronicsmentioning

confidence: 99%

Materials and Structures toward Soft Electronics

et al. 2018

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“…3D architecture control in functional devices has opened up unprecedented opportunities beyond those offered by their 2D counterparts . Among various options, 3D printing stands out in their freedom to manipulate geometric shapes in an almost unlimited fashion .…”

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confidence: 99%

Rapid Open‐Air Digital Light 3D Printing of Thermoplastic Polymer

et al. 2019

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printing is, however, limited by various factors, with printing speed and material versatility being the most decisive. From the standpoint of printing speed, layerwise printing by digital light processing (DLP) offers significant inherent advantage over point-wise printing by most other methods such as fused deposition modeling (FDM) and stereolithography (SLA). [20] Further innovations on DLP such as continuous building in the z-dimension allow achieving a printing speed far exceeding any other methods. [21][22][23] Recent attempt on direct forming 3D object in a volumetric fashion forgoes even the layer-wise printing, but the technique has yet to evolve into the mainstream. [24,25] Generally, DLP employs light curable liquid resins. Upon digital light exposure, the resin cross-links and forms a thermoset polymer that ensures its separation from the surrounding liquid precursors. This rapid liquid-solid separation is the key enabling characteristic for DLP. Although cross-linking ensures such, the resulting thermoset polymers cannot be reprocessed. This prohibits its broader utility in situations that require further processing of the printed materials. In principle, this limitation can be overcome if the DLP processing can be extended to reprocessable thermoplastic polymers. Although light curable thermoplastic polymers are known, meeting the unique DLP requirement for rapid separation between the liquid monomer and the un-crosslinked polymer is not straightforward because of their intrinsic good miscibility. Hereafter, we describe our successful attempt in DLP printing of a thermoplastic polymer and lay out key enabling factors for such a process. We further illustrate that the water dissolvable nature of the resulting polymer is advantageous in making various multifunctional 3D structures. We find that the oxygen naturally present in ambient air can inhibit the light curing process. This effect can be utilized to achieve rapid open-air printing without the complex interfacial engineering typically required for fast DLP printing methods. [21][22][23] We hypothesize that two key factors should be carefully considered for DLP printing of thermoplastic polymers (Figure 1a). Herein, two concurrent and competing processes occur: 1) the polymerization and 2) the diffusion/dissolution of the polymer into the surrounding uncured liquid monomer. Rapid liquidsolid separation is possible only if the first process dominates 3D printing has witnessed a new era in which highly complexed customized products become reality. Realizing its ultimate potential requires simultaneous attainment of both printing speed and product versatility. Among various printing techniques, digital light processing (DLP) stands out in its high speed but is limited to intractable light curable thermosets. Thermoplastic polymers, despite their reprocessibility that allows more options for further manipulation, are restricted to intrinsically slow printing methods such as fused deposition modeling. Extending DLP to thermoplastics is highly desirabl...

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“…Examples include photocurable resin and azobenzene. Photocurable resin undergoes volume shrinkage upon illumination due to cross‐linking between monomers and cross‐linkers while azobenzene exhibits volume expansion under UV light due to a trans‐to‐cis conversion with different functional group orientations in 3D space (see Figure n–o). In some other materials, a light‐induced volume change is induced by the heat caused by the light exposure .…”

Section: Bioinspired Shape‐changing Structures By 3d Printingmentioning

confidence: 99%

“…These techniques achieve anisotropic molecular densities and orientations through controlling operation conditions of 3D‐printing processes, which contribute to the macroscopic shape‐changing behaviors of the resultant structures. Examples of the guided molecular self‐assembly techniques include tuning cross‐linking density of polymerization and aligning liquid crystal, etc.…”

Section: Bioinspired Shape‐changing Structures By 3d Printingmentioning

confidence: 99%

“…A cross‐linking density gradient in polymers can be achieved by tuning the process parameters during the fabrication process, such as the light dose exposure in SLA(as shown in Figure k–o) or the heating temperature and moving speed of the nozzle in FDM . This gradient gives rise to an anisotropic swelling property in response to moisture in moisture‐induced deformable materials, such as hydrogel, and an anisotropic shrinkage rate in response to heat in heat‐induced polymer materials . The shrinkage is constrained by the building platform during the fabrication process, yielding a strain gradient within the 3D‐printed structures.…”

Section: Bioinspired Shape‐changing Structures By 3d Printingmentioning

confidence: 99%

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Recent Progress in Biomimetic Additive Manufacturing Technology: From Materials to Functional Structures

et al. 2018

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Nature has developed high-performance materials and structures over millions of years of evolution and provides valuable sources of inspiration for the design of next-generation structural materials, given the variety of excellent mechanical, hydrodynamic, optical, and electrical properties. Biomimicry, by learning from nature's concepts and design principles, is driving a paradigm shift in modern materials science and technology. However, the complicated structural architectures in nature far exceed the capability of traditional design and fabrication technologies, which hinders the progress of biomimetic study and its usage in engineering systems. Additive manufacturing (three-dimensional (3D) printing) has created new opportunities for manipulating and mimicking the intrinsically multiscale, multimaterial, and multifunctional structures in nature. Here, an overview of recent developments in 3D printing of biomimetic reinforced mechanics, shape changing, and hydrodynamic structures, as well as optical and electrical devices is provided. The inspirations are from various creatures such as nacre, lobster claw, pine cone, flowers, octopus, butterfly wing, fly eye, etc., and various 3D-printing technologies are discussed. Future opportunities for the development of biomimetic 3D-printing technology to fabricate next-generation functional materials and structures in mechanical, electrical, optical, and biomedical engineering are also outlined.

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Origami by frontal photopolymerization

Abstract: A novel method to create 3D origami structures was developed using frontal photopolymerization with grayscale light.

Cited by 203 publications

References 41 publications

Materials and Structures toward Soft Electronics

Materials and Structures toward Soft Electronics

Rapid Open‐Air Digital Light 3D Printing of Thermoplastic Polymer

Recent Progress in Biomimetic Additive Manufacturing Technology: From Materials to Functional Structures

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