4D Printed Hydrogels: Fabrication, Materials, and Applications

Dong, Yuting; Wang, Shancheng; Ke, Yujie; Ding, Liang; Zeng, Xin; Magdassi, Shlomo; Long, Yi

doi:10.1002/admt.202000034

Cited by 102 publications

(87 citation statements)

References 127 publications

(140 reference statements)

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“…Several aqueous photosensitive resins have been developed for VP to construct shape memory hydrogel (SMH) structures that are thermo‐ (e.g., poly( N , N ‐dimethyl acrylamide‐ co ‐stearyl acrylate), moisture‐ (e.g., poly(ethylene glycol‐ co‐ 2‐hydroxyethyl methacrylate)), or chemical‐responsive (e.g., alginate/polyacrylamide). [ 84 ] Moisture‐responsive SMHs, for example, the PEG diacrylate‐based SMH developed by Zhao et al., depend on the absorption/desorption (swelling/de‐swelling) of solvents for shape memory effect (Figure 9c), [ 82 ] whereas chemical‐responsive SMHs rely on changes to the electrostatic interactions between polymer chains (e.g., pH or ion concentration change) for shape change. Owing to their soft nature, high hydrophilicity and possible biocompatibility, SMH structures are desirable for stents, self‐healing structures, and soft actuators.…”

Section: Photosensitive Resinsmentioning

confidence: 99%

Recent Progress on Polymer Materials for Additive Manufacturing

Tan

Zhu

Zhou

2020

Adv Funct Materials

443

238

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Additive manufacturing (AM) is the process of printing 3D objects in a layer-by-layer manner. Polymers and their composites are some of the most widely used materials in modern industries and are of great interest in the field of AM due to their vast potential for various applications, especially in the medical, aerospace, and automotive industries. Many studies have been conducted to develop new polymer materials for AM techniques, which include vat photopolymerization, material jetting, powder bed fusion, material extrusion, binder jetting, and sheet lamination. Although several reviews on the development of polymer materials for AM have been published, most of them only focus on a specific application, process, or type of material. Therefore, this article serves to provide a comprehensive review on the progress in polymer material development for AM techniques. It begins with an introduction to different AM techniques, followed by highlighting the progress of their development. Material requirements, notable advances in newly developed materials and their potential applications are discussed in detail and summarized. This review concludes by identifying the major challenges currently encountered in using AM for polymer materials and providing insights into the valuable opportunities it presents, in hopes of spurring further development in this field.

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Section: Photosensitive Resinsmentioning

confidence: 99%

Recent Progress on Polymer Materials for Additive Manufacturing

Tan

Zhu

Zhou

2020

Adv Funct Materials

443

238

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“…Hydrogels are highly viscous and printable by several technologies, mainly DIW printing, [44,52,[57][58][59] which makes them suitable for 3D printing soft robotics. [60,61] Hydrogels can also be printed by SLA, [43] which has a better resolution using photocurable hydrogel monomers. Although the latter approach is less common, due to the lack of efficient water-soluble photoinitiators, a few soft robotic devices that were printed by SLA were demonstrated.…”

Section: Flexible and Stretchable Materialsmentioning

confidence: 99%

“…[38,68] Other applications for soft robotics, in which hydrogels are utilized, are sensors [44,52,58,69] and actuators. [52,57,[59][60][61][62][63][64]66,70] These devices rely on the key feature of hydrogels to absorb high content of water, as well as their electrical conductivity (either ionic conductivity in the presence of electrolytes [69] or conductivity provided by embedded conductive fillers [58] ). An autonomously operating soft robotic device should have a sensing ability, for example in a gripper, to provide information on location and pressure upon contact.…”

Section: Flexible and Stretchable Materialsmentioning

confidence: 99%

“…Other, less common triggers, are light, magnetic and electric field. [60,61] Chang et al [52] 3D printed by DIW, an actuator (as well as a humidity strain sensor), composed of a unique egg-white (EW) based stretchable hydrogel, which was physically crosslinked by cations. The actuator was fabricated with a gradient of crosslinking density along its thickness.…”

Section: Flexible and Stretchable Materialsmentioning

confidence: 99%

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3D Printing Materials for Soft Robotics

et al. 2020

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that uses the sensor-generated information to accurately regulate and enhance the dynamic performance.Soft robots (and more in general soft material-based systems) can be built with a plethora of materials and composites having very different mechanical properties, spanning from fluids (i.e., liquid metals, etc.) and hydrogels, to stiff solids (i.e., acrylonitrile butadiene styrene (ABS), epoxy resins, etc.). Also, in most cases, the constituent materials have many degrees of freedom and are highly non-linear, with relevant hysteresis and viscoelastic behavior. Hence, modeling soft systems is a very challenging task, and it still misses a comprehensive theoretical foundation. [19] As a result, the modeling phase is often overlooked in the design process, which in most cases relies on trial and error experimentation. The most commonly used materials in the design of soft robotics are silicone-based elastomers, such as polydimethylsiloxane (PDMS). They are used as the flexible material in pneumatic actuators, [4,5,14] in magnetic actuators, [11] and in electrically driven actuators as well, usually along with a conductive layer, commonly a carbon-based material. [15,16] Besides, other flexible polymers such as polyimides, [8] polyurethanes (PU), [12,20] or hydrogels [9] are used. So far, most devices are fabricated by casting or molding of liquid monomers, followed by hardening by UV light or heat.3D printing is an additive manufacturing technique, in which a required material is deposited, layer by layer, to form a 3D object, that is, it is a sequential 2D printing. The main advantages of 3D printing over subtractive manufacturing methods, are the simplicity of the process and the ability to form complex and hollow structures. There is a variety of 3D printing technologies that are commercially available, as described in a diversity of review reports. [21][22][23] Therefore, we will present here only a concise description of the printing technologies that are most relevant to soft robotics, all of them are based on ink compositions which are liquid during the printing processes.The most widely used methods are based on extrusion of materials, called fused deposition modeling (FDM) [24,25] and direct ink writing (DIW). [26,27] Both methods rely on a material that is extruded through a nozzle onto a substrate, and differ by the materials being used, the nozzle's nature, and the fixation mechanism. In FDM, a thermoplastic filament is extruded through a heated nozzle, followed by solidification upon cooling on the substrate, to form a solid 2D layer. This technique is simple and not expensive, but is limited to thermoplastic polymers and has relatively low resolution. In DIW, a viscous Soft robotics is a growing field of research, focusing on constructing motorless robots from highly compliant materials, some are similar to those found in living organisms. Soft robotics has a high potential for applications in various fields such as soft grippers, actuators, and biomedical devices. 3D printing of soft robotics present...

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“…More recently, there has been a growing interest in using state-of-the-art in fabrication technology, additive manufacturing (AM), to circumvent these issues. [22][23][24] This technology offers multiple advantages over traditional techniques, including fabricating complex designs, multimaterial printing, rapid prototyping, and high spatial resolution. [25] In addition, AM produces less waste than traditional approaches for manufacturing electronics, making it more sustainable.…”

Section: Introductionmentioning

confidence: 99%

Additive Manufacturable Materials for Electrochemical Biosensor Electrodes

Elbadawi

Ong

Pollard

et al. 2020

Adv Funct Materials

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With the impending Industrial Revolution 4.0, the information produced by sensors will be central in many applications. This includes the healthcare sector, where affordable healthcare and precision medicine are highly sought after. Electrochemical sensors have the potential to produce affordable, high sensitivity and specificity, intuitive, and rapid point‐of‐care diagnostics. Underpinning these achievements is the choice of material and the fabrication thereof. In this review, the different types of materials used in electrochemical biosensors are reported, with a focus on synthetic conductive materials. The review demonstrates that there is an abundance of materials to select from, and compositing different types of materials further widens their applicability in biosensors. In addition, the fabrication of such materials using the state‐of‐the‐art of fabrication technology, additive manufacturing (AM), is also detailed. The need for compositing is evident in AM, as the feedstock for certain AM technologies is inherently nonconductive. Both material choice and fabrication technologies limitations are also discussed to highlight opportunities for growth. The review highlights how recent technological advancements have the potential to drive the healthcare industry toward achieving its primary goals.

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4D Printed Hydrogels: Fabrication, Materials, and Applications

Cited by 102 publications

References 127 publications

Recent Progress on Polymer Materials for Additive Manufacturing

Recent Progress on Polymer Materials for Additive Manufacturing

3D Printing Materials for Soft Robotics

Additive Manufacturable Materials for Electrochemical Biosensor Electrodes

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