3D Printing of Hydrogel Architectures with Complex and Controllable Shape Deformation

Ji, Zhongying; Yan, Changyou; Yu, Bo; Zhang, Xiaoqin; Cai, Meirong; Jia, Xin; Wang, Xiaolong; Zhou, Feng

doi:10.1002/admt.201800713

Cited by 81 publications

(87 citation statements)

References 40 publications

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“…The great potential of 3D printing has also been exploited in the last years for the deposition of advanced functional materials, such as hydrogels, hybrid materials, porous silica or quartz, sugar scaffolds or biomaterials, among others. [ 42–49 ]…”

Section: Figurementioning

confidence: 99%

Gas‐Phase 3D Printing of Functional Materials

Huerta

Nguyễn

Sekkat

et al. 2020

Adv Materials Technologies

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Furthermore lithography and patterning are often performed in cleanrooms, thus adding to the cost of the final devices. In this context, there have been much progress in bringing the resolution of inkjet printing down to the micrometer level. [6] And other new bottom-up strategies are being developed, for example based on microfluidics and interfacial convective assembly. [7,8] Another new approach to so-called area-selective deposition (ASD) has been developed in the last years in the field of atomic layer deposition (ALD). [3,9] In ALD, solid-gas, surface-limited, selfterminating reactions take place. [10-12] This results in very compact and continuous thin films with a sub-nanometer thickness control and unique conformality, key assets for engineering the interfaces and surfaces of different functional materials and devices. [13-16] Given the surface-limited nature of ALD, several strategies can be implemented to control the reactivity of ALD precursors toward different surfaces to generate selectivity and result in ASD. These involve the use of a substrate with different materials (growth inhibition or delay taking place in one of them) or the use of self-assembled monolayers to block the growth in certain parts of the surface, as recently reviewed by Mackus et al. [17] While these approaches are very appealing and have proven to be efficient, there is still the need to have a surface with different materials, and in most cases a prepatterning step is necessary. Also, some of the ASD approaches require intermediate etching steps. [18] Finally, these approaches suffer from the inherent low deposition rate of ALD and the use of expensive vacuum equipment. In the last years, spatial ALD (SALD) has established itself as a high-throughput, low-cost alternative to conventional ALD. SALD is based on the spatial separation of precursors, as opposed to the sequential (temporal) separation in ALD. [19,20] Thus, precursors are continuously injected in different locations, which are spatially separated by an inert gas region. As the sample is exposed to the different regions, the standard ALD cycle is reproduced. Because no purge steps are needed, SALD can be up to two orders of magnitude faster than ALD. [21,22] In addition, SALD can be performed at atmospheric pressure (AP-SALD), thus resulting more convenient for scalingup than vacuum-based ALD. [23-25] But because SALD is based on the same surface-limited, self-terminating chemistry than Spatial atomic layer deposition (SALD) is a recent approach 100 times faster than conventional atomic layer deposition (ALD), even at atmospheric pressure. Previous works exploited these assets focussing on high-rate, large-area deposition for scaling-up into mass production. Conversely, this work shows that SALD indeed represents an ideal platform for area-selective deposition of functional materials by proper design and miniaturization of close-proximity SALD heads. In particular, the potential offered by 3D printing is used to fabricate low-cost customized close-proximity heads, w...

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Section: Figurementioning

confidence: 99%

Gas‐Phase 3D Printing of Functional Materials

Huerta

Nguyễn

Sekkat

et al. 2020

Adv Materials Technologies

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“…The printed composite shows a fast response time (several seconds) to multistimuli, including heat, light, and water, which is superior to most of the reported shape‐morphing materials (Figure S16, Supporting Information), especially shape‐morphing hydrogels (the composite containing GO additive in SA matrix can be regarded as hydrogel when swelling and shape‐morphing in water) . The reason can be explained as the following.…”

Section: Resultsmentioning

confidence: 99%

Spontaneous Alignment of Graphene Oxide in Hydrogel during 3D Printing for Multistimuli‐Responsive Actuation

et al. 2020

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Natural materials are often compositionally and structurally heterogeneous for realizing particular functions. Inspired by nature, researchers have designed hybrid materials that possess properties beyond each of the components. Particularly, it remains a great challenge to realize site‐specific anisotropy, which widely exists in natural materials and is responsible for unique mechanical properties as well as physiological behaviors. Herein, the spontaneous formation of aligned graphene oxide (GO) flakes in sodium alginate (SA) matrix with locally controlled orientation via a direct‐ink‐writing printing process is reported. The GO flakes are spontaneously aligned in the SA matrix by shear force when being extruded and then arranged horizontally after drying on the substrate, forming a brick‐and‐mortar structure that could anisotropically contract or expand upon activation by heat, light, or water. By designing the printing pathways directed by finite element analysis, the orientation of GO flakes in the composite is locally controlled, which could further guide the composite to transform into versatile architectures. Particularly, the transformation is reversible when water vapor is applied as one of the stimuli. As a proof of concept, complex morphing architectures are experimentally demonstrated, which are in good consistency with the simulation results.

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Section: Stimuli‐responsive Hydrogelsmentioning

confidence: 99%

“…Following the concept of asymmetric swelling, Ji et al printed polyethylene glycol diacrylate (PEG400DA)/2‐hydroxyethyl methacrylate (HEMA)‐based hydrogel structures with the anisotropic swelling property. [ 75 ] During the printing process, the grooves were printed on one side of the printed strip to guide their shape‐changing process, and the orientation of the grooves governed the direction of the asymmetrical swelling direction (Figure 5d). Figure 5e shows that the strip with perpendicular grooves spontaneously bent to a circle when subjected to swelling in water, while the inclined grooves caused the strip to twist and form a helical shape in Figure 5f.…”

Section: Stimuli‐responsive Hydrogelsmentioning

confidence: 99%