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1.
    
Additive manufacturing strives to combine any combination of materials into 3D functional structures and devices, ultimately opening up the possibility of 3D printed machines. It remains difficult to actuate such devices, thus limiting the scope of 3D printed machines to passive devices or necessitating the incorporation of external actuators that are manufactured differently. Here, 3D printed hybrid thermoplast/conducter bilayers are explored, which can be actuated by differential heating caused by externally controllable currents flowing through their conducting faces. The functionality of such actuators is uncovered and it is shown that they allow to 3D print, in one pass, simple flexible robotic structures that propel forward under step‐wise applied voltages. Moreover, exploiting the thermoplasticity of the nonconducting plastic parts at elevated temperatures, it is shown that how strong driving leads to irreversible deformations—a form of 4D printing—which also enlarges the range of linear response of the actuators. Finally, it is shown that how to leverage such thermoplastic relaxations to accumulate plastic deformations and obtain very large deformations by alternatively driving both layers of a bilayer; this is called ratcheting. The strategy is scalable and widely applicable, and opens up a new approach to reversible actuation and irreversible 4D printing of arbitrary structures and machines.  相似文献   

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4D printing has attracted tremendous interest since its first conceptualization in 2013. 4D printing derived from the fast growth and interdisciplinary research of smart materials, 3D printer, and design. Compared with the static objects created by 3D printing, 4D printing allows a 3D printed structure to change its configuration or function with time in response to external stimuli such as temperature, light, water, etc., which makes 3D printing alive. Herein, the material systems used in 4D printing are reviewed, with emphasis on mechanisms and potential applications. After a brief overview of the definition, history, and basic elements of 4D printing, the state‐of‐the‐art advances in 4D printing for shape‐shifting materials are reviewed in detail. Both single material and multiple materials using different mechanisms for shape changing are summarized. In addition, 4D printing of multifunctional materials, such as 4D bioprinting, is briefly introduced. Finally, the trend of 4D printing and the perspectives for this exciting new field are highlighted.  相似文献   

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A new method for complex metallic architecture fabrication is presented, through synthesis and 3D‐printing of a new class of 3D‐inks into green‐body structures followed by thermochemical transformation into sintered metallic counterparts. Small and large volumes of metal‐oxide, metal, and metal compound 3D‐printable inks are synthesized through simple mixing of solvent, powder, and the biomedical elastomer, polylactic‐co‐glycolic acid (PLGA). These inks can be 3D‐printed under ambient conditions via simple extrusion at speeds upwards of 150 mm s–1 into millimeter‐ and centimeter‐scale thin, thick, high aspect ratio, hollow and enclosed, and multi‐material architectures. The resulting 3D‐printed green‐bodies can be handled immediately, are remarkably robust, and may be further manipulated prior to metallic transformation. Green‐bodies are transformed into metallic counterparts without warping or cracking through reduction and sintering in a H2 atmosphere at elevated temperatures. It is shown that primary metal and binary alloy structures can be created from inks comprised of single and mixed oxide powders, and the versatility of the process is illustrated through its extension to more than two dozen additional metal‐based materials. A potential application of this new system is briefly demonstrated through cyclic reduction and oxidation of 3D‐printed iron oxide constructs, which remain intact through numerous redox cycles.  相似文献   

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There is a specialized niche for the electrohydrodynamic jetting of melts, from biomedical products to filtration and soft matter applications. The next frontier includes optics, microfluidics, flexible electronic devices, and soft network composites in biomaterial science and soft robotics. The recent emphasis on reproducibly direct‐writing continual molten jets has enabled a spectrum of contemporary microscale 3D objects to be fabricated. One strong suit of melt processing is the capacity for the jet to solidify rapidly into a fiber, thus fixing a particular structure into position. The ability to direct‐write complex and multiscaled architectures and structures has greatly contributed to a large number of recent studies, explicitly, toward fiber–hydrogel composites and fugitive inks, and has expanded into several biomedical applications such as cartilage, skin, periosteum, and cardiovascular tissue engineering. Following the footsteps of a publication that summarized melt electrowriting literature up to 2015, the most recent literature from then until now is reviewed to provide a continuous and comprehensive timeline that demonstrates the latest advances as well as new perspectives for this emerging technology.  相似文献   

6.
    
The three‐dimensional (3D) printed electronics additive manufacturing industry sector has grown substantially in the past few years, and there is increasing demand for different types of metallic nanoparticle inks in electronics printing for various applications. Metallic nanoparticle inks are commonly used for fabricating conductive tracks and patterns due to their relatively high electrical conductivity as compared to other types of inks, and they can be further categorized into single‐element metallic nanoparticle inks, alloy metallic nanoparticle inks, metallic oxide nanoparticle inks, and core–shell bimetallic nanoparticle (BNP) inks. It is critical to gain a deep understanding of the metallic nanoparticle inks used in 3D printed electronics as the material properties of these inks can directly affect the final electrical and mechanical properties of the printed patterns. This review presents an overview of the available metallic nanoparticle inks used for 3D printing of electronics, and critically reviews the strengths and weaknesses of each type of ink. Finally, the challenges of metallic nanoparticle inks in 3D printed electronics are also discussed along with the future outlook for 3D printed electronics.  相似文献   

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The field of bioelectronics with the aim to contact cells, cell clusters, biological tissues and organoids has become a vast enterprise. Currently, it is mainly relying on classical micro- and nanofabrication methods to build devices and systems. Very recently the field is highly pushed by the development of novel printable organic, inorganic and biomaterials as well as advanced digital printing technologies such as laser and inkjet printing employed in this endeavor. Recent advantages in alternative additive manufacturing and 3D printing methods enable interesting new routes, in particular for applications requiring the incorporation of delicate biomaterials or creation of 3D scaffold structures that show a high potential for bioelectronics and building of hybrid bio-/inorganic devices. Here the current state of printed 2D and 3D electronic structures and related lithography techniques for the interfacing of electronic devices with biological systems are reviewed. The focus lies on in vitro applications for interfacing single cell, cell clusters, and organoids. Challenges and future prospects are discussed for all-printed hybrid bio/electronic systems targeting biomedical research, diagnostics, and health monitoring.  相似文献   

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Additive manufacturing (AM) allows the fabrication of customized bone scaffolds in terms of shape, pore size, material type, and mechanical properties. Combined with the possibility to obtain a precise 3D image of the bone defects using computed tomography or magnetic resonance imaging, it is now possible to manufacture implants for patient-specific bone regeneration. This paper reviews the state-of-the-art of the different materials and AM techniques used for the fabrication of 3D-printed scaffolds in the field of bone tissue engineering. Their advantages and drawbacks are highlighted. For materials, specific criteria, are extracted from a literature study: biomimetism to native bone, mechanical properties, biodegradability, ability to be imaged (implantation and follow-up period), histological performances, and sterilization process. AM techniques can be classified in three major categories: extrusion-based, powder-based, and vat photopolymerization. Their price, ease of use, and space requirement are analyzed. Different combinations of materials/AM techniques appear to be the most relevant depending on the targeted clinical applications (implantation site, presence of mechanical constraints, temporary or permanent implant). Finally, some barriers impeding the translation to human clinics are identified, notably the sterilization process.  相似文献   

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In recent years, bulk metallic glasses (BMGs) have drawn much research attention and are shown to be of industrial interest due to their superior mechanical properties and resistance to corrosion. In spite of the interest in harnessing MG for microelectromechanical systems devices, there are limitations in manufacturing such micrometer‐scale structures. A novel approach for the fabrication of 3D MG structures using laser‐induced forward transfer (LIFT) is demonstrated. Inherent tremendous cooling rates associated with the metal LIFT process (≈1010 k s?1) make the formation of a variety of BMGs accessible, including also various binary compositions. In this work, it is demonstrated that LIFT printing of ZrPd‐based metallic glass microstructures can also be performed under ambient conditions. X‐ray diffraction analysis of the printed structures reveals > 95% of amorphous metal phase. Taking advantage of the properties of BMG, high quality printing of high aspect ratio BMG pillars, and microbridges are demonstrated. It is also shown how a composite, amorphous‐crystalline metal structure with a required configuration can be fabricated using multimaterial LIFT printing. The inherent high resolution of the method combined with the noncontact and multimaterial printing capacity makes LIFT a valuable additive manufacturing technique to produce metallic glass‐based devices.  相似文献   

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To accomplish the potential of the New-Space emerging era and facilitate scientific and commercial space exploration, the development of versatile, customized, and affordable space technologies is essential. 3D printing is established as a disruptive technology, enabling the production of complex and lightweight structures with enhanced performance. However, the harsh conditions of the space environment, including atomic oxygen (AO), extreme temperatures, and ionizing radiation, pose significant challenges to the durability and longevity of additive manufacturing-produced polymers. Until now, there are no additive-manufacturing polymeric materials that are specifically developed and qualified to withstand space hazards. To address these challenges, novel materials for additive manufacturing, composed of cyanate ester and extended-bismaleimide are engineered to withstand the extreme conditions in space. The developed materials demonstrate superior thermo-mechanical properties (flexural stress of 72 MPa and Tg = 260 °C), enhanced durability to AO erosion, ionizing radiation (10 years in orbit), and thermal stability (Td5% = 360 °C). Moreover, it is found that printing orientation governs the AO erosion, thus guiding optimal printing designs for enhanced durability to AO. The materials show improved performance, endurance, and reliability, thus contributing to the development of space-qualified components and enabling the advancement of additive manufacturing for future space missions.  相似文献   

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Herein, various 3D additive manufacturing approaches are reviewed in terms of two important figures of merit: maximum voxel printing rate and minimum voxel size. Voxel sizes from several 100 µm down to the 100 nm scale are covered. Original results on multifocus two‐photon printing at around voxel printing rates of 107 voxels s?1 are presented in this context, which significantly surpass previous best values. These advances are illustrated by and applied to the making of microstructured 3D (chiral) mechanical metamaterials that are composed of more than one‐hundred‐thousand unit cells in three dimensions. Previous best values for unit cells of similar complexity are smaller by two orders of magnitude.  相似文献   

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The use of non-toxic and low-cost vitamins like α-tocopherol (α-TCP, vitamin E) to improve the photophysical properties and stability of perovskite nanocrystals (PNCs), through post-synthetic ligand surface passivation, is demonstrated for the first time. Especially interesting is its effect on CsPbI3 the most unstable inorganic PNC. Adding α-TCP produces that the photoluminescence quantum yield (PLQY) of freshly prepared and aged PNCs achieves values of ≈98% and 100%, respectively. After storing 2 months under ambient air and 60% relative humidity, PLQY is maintained at 85% and 67%, respectively. α-TCP restores the PL features of aged CsPbI3 PNCs, and mediates the radiative recombination channels by reducing surface defects. In addition, the combination of α-TCP and PNCs facilitates the chemical formulation to prepare PNCs-acrylic polymer composites processable by additive manufacturing. This enables the development of complex shaped parts with improved luminescent features and long-term stability for 4 months, which is not possible for non-modified PNCs. A PLQY ≈92% is reached in the 3D printed polymer/PNC composite, the highest value obtained for a red-emitting composite solid until now as far as it is known. The passivation shell provided by α-TCP makes that PNCs inks do not suffer any degradation process avoiding the contact with the environment and preserve their properties after reacting with polar monomers during composite polymerization.  相似文献   

14.
    
Liquid metal (LM) elastomer composites offer promising potential in soft robotics, wearable electronics, and human-machine interfaces. Direct ink write (DIW) 3D printing offers a versatile manufacturing technique capable of precise control over LM microstructures, yet challenges such as interfilament void formation in multilayer structures impact material performance. Here, a DIW strategy is introduced to control both LM microstructure and material architecture. Investigating three key process parameters–nozzle height, extrusion rate, and nondimensionalized nozzle velocity–it is found that nozzle height and velocity predominantly influence filament geometry. The nozzle height primarily dictates the aspect ratio of the filament and the formation of voids. A threshold print height based on filament geometry is identified; below the height, significant surface roughness occurs, and above the ink fractures, which facilitates the creation of porous structures with tunable stiffness and programmable LM microstructure. These porous architectures exhibit reduced density and enhanced thermal conductivity compared to cast samples. When used as a dielectric in a soft capacitive sensor, they display high sensitivity (gauge factor = 9.0), as permittivity increases with compressive strain. These results demonstrate the capability to simultaneously manipulate LM microstructure and geometric architecture in LM elastomer composites through precise control of print parameters, while maintaining geometric fidelity in the printed design.  相似文献   

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This study introduces a novel solution to the design of structured catalysts, integrating single-piece 3D printing with single-atom catalysis. Structured catalysts are widely employed in industrial processes, as they provide optimal mass and heat transfer, leading to a more efficient use of catalytic materials. They are conventionally prepared using ceramic or metallic bodies, which are then washcoated and impregnated with catalytically active layers. However, this approach may lead to adhesion issues of the latter. By employing photopolymerization printing, a stable and active single-atom catalyst is directly shaped into a stand-alone, single-piece structured material. The battery of characterization methods employed in the present study confirms the uniform distribution of catalytically active species and the structural integrity of the material. Computational fluid dynamics simulations are applied to demonstrate enhanced momentum transfer and light distribution within the structured body. The materials are finally evaluated in the continuous-flow photocatalytic oxidation of benzyl alcohol to benzaldehyde, a relevant reaction to prepare biomass-derived building blocks. The innovative approach reported herein to manufacture a structured single-atom catalyst circumvents the complexities of traditional synthetic methods, offering scalability and efficiency improvements, and highlights the transformative role of 3D printing in catalysis engineering to revolutionize catalysts’ design.  相似文献   

16.
    
3D‐printing represents an emerging technology that can revolutionize the way object and functional devices are fabricated. Here the use of metal 3D printing is demonstrated to fabricate bespoke electrochemical stainless steel electrodes that can be used as platform for different electrochemical applications ranging from electrochemical capacitors, oxygen evolution catalyst, and pH sensor by means of an effective and controlled deposition of IrO2 films. The electrodes have been characterized by scanning electrode microscopy and energy dispersive X‐ray spectroscopy before the electrochemical testing. Excellent pseudocapacitive as well as catalytic properties have been achieved with these 3D printed steel‐IrO2 electrodes in alkaline solutions. These electrodes also demonstrate Nernstian behavior as pH sensor. This work represents a breakthrough in on‐site prototyping and fabrication of highly tailored electrochemical devices with complex 3D shapes which facilitate specific functions and properties.  相似文献   

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3D printing, also known as additive manufacturing, is a manufacturing process in which the materials are deposited layer by layer in an additive manner. With the advancement in materials and manufacturing technology, 3D printing has found its applications in the field of electronics manufacturing. Initially, 3D printing is used for the fabrication of electronic components with single material designs such as resistors, inductors, circuits, antennas, strain gauges, etc. Recently, there are many works involving the use of 3D printing fabrication techniques for advanced electronic components and devices such as parallel plate capacitors, inductors, organic light-emitting diodes, photovoltaics, transistors, displays, etc. which involve multilayer multimaterial printing. Despite these many works, there has been no review on the design and fabrication consideration for the 3D printing of multilayered and multimaterial (MLMM) electronics. As such, this review aims to summarize the current landscape of 3D printing of MLMM electronics and provide some insights on the design consideration, fabrication strategies, and challenges of 3D printing of MLMM electronics. In particular, the focus will be placed on discussing the interface conditions between different materials such as surface wettability, surface roughness, material compatibility, and the considerations for postprocessing treatments.  相似文献   

20.
    
Additive manufacturing, i.e., 3D printing, is being increasingly utilized to fabricate a variety of complex‐shaped electronics and energy devices (e.g., batteries, supercapacitors, and solar cells) due to its excellent process flexibility, good geometry controllability, as well as cost and material waste reduction. In this review, the recent advances in 3D printing of emerging batteries are emphasized and discussed. The recent progress in fabricating 3D‐printed batteries through the major 3D‐printing methods, including lithography‐based 3D printing, template‐assisted electrodeposition‐based 3D printing, inkjet printing, direct ink writing, fused deposition modeling, and aerosol jet printing, are first summarized. Then, the significant achievements made in the development and printing of battery electrodes and electrolytes are highlighted. Finally, major challenges are discussed and potential research frontiers in developing 3D‐printed batteries are proposed. It is expected that with the continuous development of printing techniques and materials, 3D‐printed batteries with long‐term durability, favorable safety as well as high energy and power density will eventually be widely used in many fields.  相似文献   

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