A Subtractive Photoresist Platform for Micro‐ and Macroscopic 3D Printed Structures

The selective removal of structural elements plays a decisive role in 3D printing applications enabling complex geometries. To date, the fabrication of complex structures on the microscale is severely limited by multistep processes. Herein, a subtractive photoresist platform technology that is transferable from microscopic 3D printing via direct laser writing to macroscopic structures via stereolithography is reported. All resist components are readily accessible and exchangeable, offering fast adaptation of the resist's property profile. The micro‐ and macroprinted structures can be removed in a facile fashion, without affecting objects based on standard photoresists. The cleavage is analyzed by time‐lapse optical microscopy as well as via in‐depth spectroscopic assessment. The mechanical properties of the printed materials are investigated by nanoindentation. Critically, the power of the subtractive resist platform is demonstrated by constructing complex 3D objects with flying features on the microscale.     

Smart Energy Bricks: Ti3C2@Polymer Electrochemical Energy Storage inside Bricks by 3D Printing

Three-dimensional (3D) printing technology has a pronounced impact on building construction and energy storage devices. Here, the concept of integrating 3D-printed electrochemical devices into insulation voids in construction bricks is demonstrated in order to create electrochemical energy storage as an integral part of home building. The low-cost 3D-printed supercapacitor (SC) electrodes are created using graphene/polylactic acid (PLA) filament in any desired shape such as 3D cylindrical- (3Dcy), disk- (3Ddc), and 3D rectangular- (3Drc) shaped electrodes. To obtain excellent capacitive performance, a Ti₃C₂@polypyrrole (PPy) hybrid is uniformly electroplated on the surface of 3D-printed electrodes. These Ti₃C₂@PPy-coated 3D-printed electrodes exhibit outstanding electrical conductivity, capacitive performance, cycle life, and power density. The bricks themselves act as an excellent scaffold for electrochemical energy devices as they are electrically insulating, fire-resistant, and contain substantial unused thermal insulation voids. A 3Drc Ti₃C₂@PPy SC is integrated into a real brick to showcase a smart house energy storage system that allows to reserve power in the bricks and use it as a power backup source in the event of a power outage in the elevator. This concept provides a platform for future truly smart buildings built from added value “smart brick” energy storage systems.     

3D Printing of Arbitrary Perovskite Nanowire Heterostructures

Deterministic integration of arbitrary semiconductor heterostructures opens a new class of modern electronics and optoelectronics. However, the realization of such heterostructures continues to suffer from impracticality, requiring energy- and labor-intensive, time-consuming fabrication processes. Here a 3D printing approach to fabricate freestanding metal halide perovskite nanowire heterostructures with a high degree of control over shape and composition is demonstrated. These features arise from freeform guiding of evaporation-driven perovskite crystallization by a femtoliter precursor meniscus formed on a printing nozzle. By using a double-barreled nanopipette as a printing nozzle, “all-at-once” heterostructure fabrication is achieved within seconds. The 3D-printed perovskite nanowire heterojunctions with multiple emission colors provide exciting optical functionalities such as programmable color mixing and encryption at the single nanopixel level. This “lithography-free” additive approach opens up the possibility to freely design and realize heterostructure-based devices without the constraints of traditional manufacturing processes.     

3D-Printed Photoresponsive Liquid Crystal Elastomer Composites for Free-Form Actuation

Direct ink writing of liquid crystal elastomers (LCEs) offers a new opportunity to program geometries for a wide variety of shape transformation modes toward applications such as soft robotics. So far, most 3D-printed LCEs are thermally actuated. Herein, a 3D-printable photoresponsive gold nanorod (AuNR)/LCE composite ink is developed, allowing for photothermal actuation of the 3D-printed structures with AuNR as low as 0.1 wt.%. It is shown that the printed filament has a superior photothermal response with 27% actuation strain upon irradiation to near-infrared (NIR) light (808 nm) at 1.4 W cm⁻² (corresponding to 160 °C) under optimal printing conditions. The 3D-printed composite structures can be globally or locally actuated into different shapes by controlling the area exposed to the NIR laser. Taking advantage of the customized structures enabled by 3D printing and the ability to control locally exposed light, a light-responsive soft robot is demonstrated that can climb on a ratchet surface with a maximum speed of 0.284 mm s⁻¹ (on a flat surface) and 0.216 mm s⁻¹ (on a 30° titled surface), respectively, corresponding to 0.428 and 0.324 body length per min, respectively, with a large body mass (0.23 g) and thickness (1 mm).     

3D Printing of a Biocompatible Double Network Elastomer with Digital Control of Mechanical Properties

The majority of 3D‐printed biodegradable biomaterials are brittle, limiting their application to compliant tissues. Poly(glycerol sebacate) acrylate (PGSA) is a synthetic biocompatible elastomer and compatible with light‐based 3D printing. In this article, digital‐light‐processing (DLP)‐based 3D printing is employed to create a complex PGSA network structure. Nature‐inspired double network (DN) structures consisting of interconnected segments with different mechanical properties are printed from the same material in a single shot. Such capability has not been demonstrated by any other fabrication techniques so far. The biocompatibility of PGSA is confirmed via cell‐viability analysis. Furthermore, a finite‐element analysis (FEA) model is used to predict the failure of the DN structure under uniaxial tension. FEA confirms that the DN structure absorbs 100% more energy before rupture by using the soft segments as sacrificial elements while the hard segments retain structural integrity. Using the FEA‐informed design, a new DN structure is printed and tensile test results agree with the simulation. This article demonstrates how geometrically‐optimized material design can be easily and rapidly constructed by DLP‐based 3D printing, where well‐defined patterns of different stiffnesses can be simultaneously formed using the same elastic biomaterial, and overall mechanical properties can be specifically optimized for different biomedical applications.     

Limpet Tooth-Inspired Painless Microneedles Fabricated by Magnetic Field-Assisted 3D Printing

Microneedle arrays show many advantages in drug delivery applications due to their convenience and reduced risk of infection. Compared to other microscale manufacturing methods, 3D printing easily overcomes challenges in the fabrication of microneedles with complex geometric shapes and multifunctional performance. However, due to material characteristics and limitations on printing capability, there are still bottlenecks to overcome for 3D printed microneedles to achieve the mechanical performance needed for various clinical applications. The hierarchical structures in limpet teeth, which are extraordinarily strong, result from aligned fibers of mineralized tissue and protein-based polymer reinforced frameworks. These structures provide design inspiration for mechanically reinforced biomedical microneedles. Here, a bioinspired microneedle array is fabricated using magnetic field-assisted 3D printing (MF-3DP). Micro-bundles of aligned iron oxide nanoparticles (aIOs) are encapsulated by polymer matrix during the printing process. A bioinspired 3D-printed painless microneedle array is fabricated, and suitability of this microneedle patch for drug delivery during long-term wear is demonstrated. The results reported here provide insights into how the geometrical morphology of microneedles can be optimized for the painless drug delivery in clinical trials.     

Reconciling Mass Loading and Gravimetric Performance of MnO2 Cathodes by 3D-Printed Carbon Structures for Zinc-Ion Batteries

To promote the real application of zinc-ion batteries (ZIBs), reconciling the high mass loading and gravimetric performance of MnO₂ electrodes is of paramount importance. Herein, the rational regulation of 3D-printed carbon microlattices (3DP CMs) enabling an ultrathick MnO₂ electrode with well-maintained gravimetric capacities is demonstrated. The 3DP CMs made of graphene and carbon nanotubes (CNTs) are fabricated by direct ink 3D printing and subsequent high-temperature annealing. 3D printing enables a periodic structure of 3DP CMs, while the thermal annealing contributes to high conductivity and defective surfaces. Due to these structural merits, uniform electrical field distribution and facilitated MnO₂ deposition over the 3DP CMs are permitted. The optimal electrode with MnO₂ loaded on the 3DP CMs can achieve a record-high specific capacity of 282.8 mAh g⁻¹ even at a high mass loading of 28.4 mg cm⁻² and high ion transfer dynamics, which reconciles the loading mass and gravimetric performance. As a result, the aqueous ZIBs based on the 3DP CMs loaded MnO₂ afford an outstanding performance superior to most of the previous reports. This study reveals the essential role of interaction between active materials and current collectors, providing an alternative strategy for designing high-performance energy storage devices.     

3D Printing of Multifunctional Conductive Polymer Composite Hydrogels

Functional conductive hydrogels are widely used in various application scenarios, such as artificial skin, cell scaffolds, and implantable bioelectronics. However, their novel designs and technological innovations are severely hampered by traditional manufacturing approaches. Direct ink writing (DIW) is considered a viable industrial-production 3D-printing technology for the custom production of hydrogels according to the intended applications. Unfortunately, creating functional conductive hydrogels by DIW has long been plagued by complicated ink formulation and printing processes. In this study, a highly 3D printable poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)-based ink made from fully commercially accessible raw materials is demonstrated. It is shown that complex structures can be directly printed with this ink and then precisely converted into high-performance hydrogels via a post-printing freeze–thawing treatment. The 3D-printed hydrogel exhibits high electrical conductivity of ≈2000 S m⁻¹, outstanding elasticity, high stability and durability in water, electromagnetic interference shielding, and sensing capabilities. Moreover, the hydrogel is biocompatible, showing great potential for implantable and tissue engineering applications. With significant advantages, the fabrication strategy is expected to open up a new route to create multifunctional hydrogels with custom features, and can bring new opportunities to broaden the applications of hydrogel materials.     

Two-Photon Polymerization Lithography for Optics and Photonics: Fundamentals,Materials, Technologies,and Applications

The rapid development of additive manufacturing has fueled a revolution in various research fields and industrial applications. Among the myriad of advanced 3D printing techniques, two-photon polymerization lithography (TPL) uniquely offers a significant advantage in nanoscale print resolution, and has been widely employed in diverse fields, for example, life sciences, materials sciences, mechanics, and microfluidics. More recently, by virtue of the optical transparency of most of the resins used, TPL is finding new applications in optics and photonics, with nanometer to millimeter feature dimensions. It enables the minimization of optical elements and systems, and exploration of light-matter interactions with new degrees of freedom, never possible before. To review the recent progress in the TPL related optical research, it starts with the fundamentals of TPL and material formulation, then discusses novel fabrication methods, and a wide range of optical applications. These applications notably include diffractive, topological, quantum, and color optics. With a panoramic view of the development, it is concluded with insights and perspectives of the future development of TPL and related potential optical applications.     

自由空间微光学元件的研制

介绍了一种新近产生的被称为自由空间微光学平台（ Ｆ Ｓ Ｍ Ｏ Ｂ）的三维空间集成光学系统。并提出了一种用二氧化硅（ Ｓｉ Ｏ２）作光学材料、光刻胶和溅射铜（ Ｃｕ）薄膜作牺牲层、电镀铁镍（ Ｆｅ Ｎｉ）作支撑结构的制作自由空间微光学元件的新工艺。研制成功了多种与基底相垂直的三维位相型微光学元件。     

Soft Robotics Programmed with Double Crosslinking DNA Hydrogels

DNA nanotechnology is developed for decades to construct dynamic responsive systems in optics, quantum electronics, and therapeutics. While DNA nanotechnology is a powerful tool in nanomaterials, it is rare to see successful applications of DNA molecules in the macroscopic regime of material sciences. Here, a novel strategy to magnify the nanometer scale DNA self‐assembly into a macroscopic mechanical responsiveness is demonstrated. By incorporating molecularly engineered DNA sequences into a polymeric network, a new type of responsive hydrogel (D‐gel), whose overall morphology is dynamically controlled by DNA hybridization‐induced double crosslinking is able to be created. As a step toward manufacturing, the D‐gel in combination with a bottom‐up 3D printing technology is employed to rapidly create modular macroscopic structures that feature programmable reconfiguration and directional movement, which can even mimic the complex gestures of human hands. Mechanical operations such as catch and release are demonstrated by a proof‐of‐concept hydrogel palm, which possessed great promise for future engineering applications. Compared with previously developed DNA hydrogels, the D‐gel features an ease of synthesis, faster response, and a high degree of programmable control. Moreover, it is possible to scale up the production of D‐gel containing responsive devices through direct 3D printing.     

Advances in 4D Printing: Materials and Applications

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.     

3D-Printed Electrostatic Microactuators for Flexible Microsystems

Developing small-scale, lightweight, and flexible devices with integrated microactuators is one of the critical challenges in wearable haptic devices, soft robotics, and microrobotics. In this study, a novel fabrication process that leverages the benefits of 3D printing with two-photon polymerization and flexible printed circuit boards (FPCBs) is presented. This method enables flexible microsystems with 3D-printed electrostatic microactuators, which are demonstrated in a flexible integrated micromirror array and a legged microrobot with a mass of 4 mg. 3D electrostatic actuators on FPCBs are robust enough to actuate the micromirrors while the device is deformed, and they are easily integrated with off-the-shelf electronics. The crawling robot is one of the lightest legged microrobots actuated without external fields, and the legs actuated with 3D electrostatic actuators enable a locomotion speed of 0.27 body length per second. The proposed fabrication framework opens up a pathway toward a variety of highly integrated flexible microsystems.     

Biomimetic 4D Printing Catapult: From Biological Prototype to Practical Implementation

4D printing technologies are currently suffering from the inability to produce rapid motions, which limit their applications that require fast shape transformation such as rapid unlocking and deployment of aerospace equipment. Herein, inspired by the shooting mechanisms of Viola verecunda fruit for seed dispersal, the 4D-printed biomimetic catapult is developed. Based on the structure change characteristics of gradient fan-shaped cells of the fruit pods during seed ejection, the biomimetic smart catapult is processed via the programming of spatial distribution of heterogeneous materials with various storage modulus enabled by additive manufacturing. This catapult can achieve high-speed ejection with the logically stimuli of external force, temperature, light, humidity, or electricity. The proposed biomimetic 4D printing strategy has broken through the limitations in motion speed, which helps fully unleash the potential of 4D printing.     

个性化3D打印产品网上交易平台的开发

随着3D打印机技术的迅速发展,3D打印产品的种类越来越多,可以满足人们对一些个性化产品的需求.3D打印产品的小比量、个性化,非常适合电子商务的消费模式.为此,设计开发了个性化的3D打印产品网上交易平台,从而实现3D打印产品的网上交易,经过测试系统运行正常.     

微型光机电系统及其制作

微型光机电系统 (MOEMS)是将微光学、微电子和微机械系统结合发展出一种新型、宽广的应用领域 ,从早期的分立光学元件与电子电路向独立完整的光学系统发展。阐述了实现MOEMS的 2种技术手段 :光波导和微型光学平台的原理、制作工艺和关键技术 ,在此基础上概要介绍了几种典型的MOEMS系统。最后对其的发展作了展望。     

The Design of 4D-Printed Hygromorphs: State-of-the-Art and Future Challenges

In recent years, 4D printing has allowed the rapid development of new concepts of multifunctional/adaptive structures. The 4D printing technology makes it possible to generate new shapes and/or property-changing capabilities by combining smart materials, multiphysics stimuli, and additive manufacturing. Hygromorphs constitute a specific class of new smart materials where their properties and morphing capabilities are dependent on the surrounding humidity, which drives actuation. Although multiple efforts have been made to fabricate hygromorph demonstrators, a comprehensive design process to produce hygromorphs by multiple 4D printing techniques is not yet available. The broad aim of this review and concept paper is to i) highlight existing scientific and technology gaps in the field of 4D-printed hygromorphs, ii) identify tools existing in other research fields for filling those gaps, and iii) discuss a series of guidelines for tackling future challenges and opportunities to develop 4D-printed composite hygromorph materials and related manufacturing processes. Accordingly, this review describes the materials and additive manufacturing techniques used for hygromorph composite fabrication. Moreover, the relevant parameters that control actuation, the models selection and performance, the design methods and the actuation measurements for customized 4D-printed hygromorph materials, are discussed.     

3D Printed Supercapacitor: Techniques,Materials, Designs,and Applications

Supercapacitors (SCs) offer broad possibilities in the rising domain of military and civilian owing to their intrinsic properties of superior power density, long lifetime, and safety features. Despite of low-cost, facile manufacture, and time-saving, 3D printing technology unleashes the potential of SCs in terms of achieving desirable capacitance with high mass loading, fabrication of well-designed complicated structures, and direct construction of on-chip integration systems. In this review, first, the representative printing technologies for SCs and advanced printable materials are scrutinized for SCs and advanced printable materials. Then the structure design principles of electrodes and devices are respectively highlighted and reported cases are systematically summarized. Next, configurations of the SCs and their applications in various areas are described in detail. Finally, the promising research directions for the future are discussed. The perspectives reviewed here are expected to provide a comprehensive understanding of 3D-printed SCs and guidance in realizing their promise in various applications.     

3D Printed Nanocarbon Frameworks for Li-Ion Battery Cathodes

The use of conductive carbon materials in 3D-printing is attracting growing academic and industrial attention in electrochemical energy storage due to the high customization and on-demand capabilities of the additive manufacturing. However, typical polymers used in conductive filaments for 3D printing show high resistivity and low compatibility with electrochemical energy applications. Removal of insulating thermoplastics in as-printed materials is a common post-printing strategy, however, excessive loss of thermoplastics can weaken the structural integrity. This work reports a two-step surface engineering methodology for fabrication of 3D-printed carbon materials for electrochemical applications, incorporating conductive poly(ortho-phenylenediamine) (PoPD) via electrodeposition. A conductive PoPD effectively enhances the electrochemical activities of 3D-printed frameworks. When PoPD-refilled frameworks casted with LiMn₂O₄ (LMO) composite materials used as battery cathode, it delivers a capacity of 69.1 mAh g⁻¹ at a current density of 0.036 mA cm⁻² ( ≈ 1.2 C discharge rate) and good cyclability with a retained capacity of 84.4% after 200 cycles at 0.36 mA cm⁻². This work provides a pathway for developing electroactive 3D-printed electrodes particularly with cost-efficient low-dimensional carbon materials for aqueous rechargeable Li-ion batteries.     

Charge-Programmable Photopolymers for 3D Electronics via Additive Manufacturing

Charge-programmed 3D printing enables the fabrication of 3D electronics with lightweight and high precision via selective patterning of metals. This selective metal deposition is catalyzed by Pd nanoparticles that are specifically immobilized onto the charged surface and promises to fabricate a myriad of complex electronic devices with self-sensing, actuation, and structural elements assembled in a designed 3D layout. However, the achievable property space and the material-performance correlation of the charge-programmed printing remain unexplored. Herein, a series of photo-curable resins are designed for unveiling how the charge and crosslink densities synergistically impact the nanocatalyst-guided selective deposition in catalytic efficiency and properties of the 3D printed charge-programmed architectures, leading to high-quality 3D patterning of solid and liquid metals. The findings offer a wide tunability of the structural properties of the printed electronics, ranging from stiff to extreme flexibility. Capitalizing on these results, the printing and successful application of an ultralight-weight and deployable 3D multi-layer antenna system operating at an ultrahigh-frequency of 19 GHz are demonstrated.