Autonomously Responsive Membranes for Chemical Warfare Protection

Stimuli‐responsive materials offer new opportunities to resolve long‐standing material challenges and are rapidly gaining pivotal roles in diverse applications. For example, smart protective garments that rapidly transport water vapor and autonomously block chemical threats are expected to enable an effective new paradigm of adaptive personal protection. However, the incorporation of these seemingly incompatible properties into a single responsive system remains elusive. Herein, a bistable membrane that can rapidly, selectively, and reversibly transition from a highly breathable state in a safe environment to a chemically protective state when exposed to organophosphate threats such as sarin is demonstrated. Dynamic response to chemical stimuli is achieved through the physical collapse of an ultrathin copolymer layer on the membrane surface, which efficiently gates transport through membrane pores composed of single‐walled carbon nanotubes (SWNTs). The adoption of nanometer‐wide SWNTs for ultrafast moisture conduction enables a simultaneous boost in size‐sieving selectivity and water‐vapor permeability by decreasing nanotube diameter, thereby overcoming the breathability/protection trade‐off that limits conventional membrane materials. Adaptive multifunctional membranes based on this platform greatly extend the active use of a protective garment and present exciting opportunities in many other areas including separation processes, sensing, and smart delivery.     

Design Principles and Material Engineering of ZnS for Optoelectronic Devices and Catalysis

ZnS, as one of the first semiconductors discovered and a rising material star, has embraced exciting breakthroughs in the past few years. To shed light on the design principles and engineering techniques of ZnS for improved/novel optoelectronic properties, the fundamental mechanisms and commonly employed strategies are proposed in this review. Recent progress on modifications of ZnS allows it to be extensively and effectively used in versatile applications, including transparent conductors, UV photodetectors, luminescent devices, and catalysis, which are clearly and comprehensively summarized in this work. Novel functional devices springing up from the newly developed ZnS‐based materials are highlighted as well. This review not only provides a scientific insight into the advances of ZnS‐based materials, but also touches on the future opportunities in this inspiring field.     

On the way to plastic computation

The development of post silicon technologies based on organic materials consolidates the possibility to realize new devices and applications with unusual properties: flexibility, lightweight, disposability. Both materials and processes play a fundamental role in this new electronic framework and have been improved continuously in the last decades. In this contribution, a new perspective will be drawn by considering a complete technology platform that lead printed organic electronics technology from the basic device and materials to a manufacturing process flow, design tools and market applications development. The final goal of the proposed approach is the manufacturing of organic circuits with sub-micron feature size at low fabrication costs with high flexibility and application versatility by using additive manufacturing processes. The identification of suitable material features and process steps and the implementation of dedicated CAD tools in a complete workflow are here reported. Moreover, the feasibility of the adopted technology is demonstrated by the design of both digital and analog circuits. Multilayered structure devices, like Organic Thin Film Transistor (OTFT), are used to design complex architectures like arithmetic logic units and nonlinear oscillators.     

Self-Repairing and Damage-Tolerant Hydrogels for Efficient Solar-Powered Water Purification and Desalination

Solar-driven interfacial evaporation has emerged as an innovative and sustainable technology for efficient, clean water production. Real-world applications depend on new classes of low-cost, lightweight, and robust materials that can be integrated into one monolithic device, which withstands a variety of realistic conditions on open water. Self-repairing building blocks are highly desired to prevent permanent failures, recover original functions and maintain the lifetime of interfacial steam generators, although related studies are scarce to date. For the first time, a monolithic, durable, and self-floating interfacial steam generator with well-defined structures is demonstrated by integrating self-healing hydrogels through facile processes in surface modulation and device fabrication. High and stable water evaporation rates over 2.0 kg m⁻² h⁻¹ are attained under 1 sun on both fresh water and brine with a broad range of salinity (36–210 g kg⁻¹). The solar evaporation and desalination performance are among the best-performing interfacial steam generators and surpass a majority of devices that are constructed by composite polymers as structural components. This study provides a perspective and highlights the future opportunities in self-healing and damage-tolerant materials that can simultaneously improve the performance, durability, and lifetime of interfacial steam generators in real-world applications.     

Defect Engineering of MOF-Based Membrane for Gas Separation

Metal–organic frameworks (MOFs) are highly versatile materials that have been identified as promising candidates for membrane-based gas separation applications due to their uniformly narrow pore windows and virtually unlimited structural and chemical features. Defect engineering of MOFs has opened new opportunities for manipulating MOF structures, providing a simple yet efficient approach for enhancing membrane separation. However, the utilization of this strategy to tailor membrane microstructures and enhance separation performance is still in its infancy. Thus, this summary aims to provide a guideline for tailoring defective MOF-based membranes. Recent developments in defect engineering of MOF-based membranes will be discussed, including the synthesis strategies for defective MOFs, the effects of defects on the gas adsorption properties, gas transport mechanisms, and recently reported defective MOF-based membranes. Furthermore, the emerging challenges and future prospects will be outlined. Overall, defect engineering offers an exciting opportunity to improve the performance of MOF-based gas membranes. However, there is still a long way to go to fully understand the influence of defects on MOF properties and optimize the design of MOF-based membranes for specific gas separation applications. Nonetheless, continued research in this field holds great promise for the development of next-generation membrane-based gas separation technologies.     

Graphene-Based Advanced Membrane Applications in Organic Solvent Nanofiltration

Owing to the increasing need to mitigate excessive organic solvent waste, the efficient separation and recovery of organic solvents have received major research attention in recent years. The membrane-based organic solvent nanofiltration (OSN) process has demonstrated its feasibility in addressing this problem with low energy costs, compared to conventional separation techniques, such as adsorption, liquid–liquid extraction, and solvent evaporation. Recently, membranes made of 2D graphene-based materials have shown great promise because they attain high solvent flux and solute rejection using easy processing methods. Thus, this paper focuses on state-of-the-art studies of graphene-based membranes used in OSN processes, which include syntheses, characterizations, performance evaluations, membrane fouling, and simulation studies, in combination with the development of the “upper-bound” line to indicate the performance of graphene-based membranes. In this paper, critical challenges involved in the development of graphene-based membranes are also focused on and discussed to map out the future directions of these membranes in industrial OSN processes. In addition to OSN, this paper pertains to a broader audience in other separation processes, particularly in the fields of gas separation and water treatment.     

Surface Charge Modification on 2D Nanofluidic Membrane for Regulating Ion Transport

2D nanofluidic membranes are capable of regulating ion transport toward various applications concerning energy and environment, which is primarily contributed by the excess charge on the interior surface of narrow nanoscale pores. However, there is still a lack of comprehensive summaries and discussions on the surface charge modification principles and strategies of 2D nanofluidic membranes, as well as the practical applications of charge-modified 2D nanofluidic membranes for regulating ion transport. In this review, the surface charge modification principles and charge modification methods of 2D nanofluidic membranes are first introduced in detail, which is of great significance for improving the ion regulation capability of membranes and realizing the design of nanochannel materials. Next, recent advances in the two typical applications of concentration cells and water treatment based on charge-modified 2D nanofluidic membranes are summarized. Finally, some challenges and prospects related to charge-modified 2D nanofluidic membranes are discussed to indicate directions for future research in this field. It is anticipated that this review will provide valuable strategies for the development of high-performance charge-modified 2D nanofluidic membranes toward energy and environment applications.     

Strategic Design of Clay‐Based Multifunctional Materials: From Natural Minerals to Nanostructured Membranes

Nature not only carefully prepares ingenious raw materials but also continuously inspires and guides human beings to create a wide variety of intelligent materials. As the most abundant mineral resource on earth, clay minerals are no longer synonymous with ceramics and cements. Many natural clay minerals can be exfoliated into single‐ or few‐layered nanosheets with exquisite physicochemical properties, which can be reassembled into functional membranes with a macroscopic controllable size and microscopic ordered structure. They are thus used in many fields including chemistry, biology, energy, and environmental science. Strategic design represents one of the key processes to enhance the value of clay minerals and broaden their applications. In this work, the three frequently used approaches of exfoliation are highlighted and the six routes of assembly including casting, dip‐coating, spray coating, vacuum filtration, electrophoretic deposition, and 3D printing are compared. The corresponding principles and advantages are summarized. Representative applications of clay‐based multifunctional membranes in protection, separation, responsiveness, flexible electronics, and energy conversion are presented. The challenges and future perspectives of the clay‐based multifunctional membranes are discussed.     

Dopamine: Just the Right Medicine for Membranes

Mussel‐inspired chemistry has attracted widespread interest in membrane science and technology. Demonstrating the rapid growth of this field over the past several years, substantial progress has been achieved in both mussel‐inspired chemistry and membrane surface engineering based on mussel‐inspired coatings. At this stage, it is valuable to summarize the most recent and distinctive developments, as well as to frame the challenges and opportunities remaining in this field. In this review, recent advances in rapid and controllable deposition of mussel‐inspired coatings, dopamine‐assisted codeposition technology, and photoinitiated grafting directly on mussel‐inspired coatings are presented. Some of these technologies have not yet been employed directly in membrane science. Beyond discussing advances in conventional membrane processes, emerging applications of mussel‐inspired coatings in membranes are discussed, including as a skin layer in nanofiltration, interlayer in metal‐organic framework based membranes, hydrophilic layer in Janus membranes, and protective layer in catalytic membranes. Finally, some critical unsolved challenges are raised in this field and some potential pathways are proposed to address them.     

Recent Progress of Conductive Hydrogel Fibers for Flexible Electronics: Fabrications,Applications, and Perspectives

Flexible conductive materials with intrinsic structural characteristics are currently in the spotlight of both fundamental science and advanced technological applications due to their functional preponderances such as the remarkable conductivity, excellent mechanical properties, and tunable physical and chemical properties, and so on. Typically, conductive hydrogel fibers (CHFs) are promising candidates owing to their unique characteristics including light weight, high length-to-diameter ratio, high deformability, and so on. Herein, a comprehensive overview of the cutting-edge advances the CHFs involving the architectural features, function characteristics, fabrication strategies, applications, and perspectives in flexible electronics are provided. The fundamental design principles and fabrication strategies are systematically introduced including the discontinuous fabrication (the capillary polymerization and the draw spinning) and the continuous fabrication (the wet spinning, the microfluidic spinning, 3D printing, and the electrospinning). In addition, their potential applications are crucially emphasized such as flexible energy harvesting devices, flexible energy storage devices, flexible smart sensors, and flexible biomedical electronics. This review concludes with a perspective on the challenges and opportunities of such attractive CHFs, allowing for better understanding of the fundamentals and the development of advanced conductive hydrogel materials.     

Acoustically actuated flextensional Si/sub x/N/sub y/ and single-crystal silicon 2-D micromachined ejector arrays

We propose using two-dimensional (2-D) micromachined droplet ejector arrays for environmentally benign deposition of photoresist and other spin-on materials, such as low-k and high-k dielectrics used in IC manufacturing. Direct deposition of these chemicals will reduce waste as well as production cost. The proposed device does not harm heat or pressure sensitive fluids and they are chemically compatible with the materials used in IC manufacturing. Each element of the 2-D ejector array consists of a flexurally vibrating circular membrane on one face of a cylindrical fluid reservoir. The membrane has an orifice at the center. A piezoelectric transducer generating ultrasonic waves, located at the open face of the reservoir, actuates the membranes. As a result of this actuation, droplets are fired through the membrane orifice. Ejector arrays were built with either Si/sub x/N/sub y/ or single-crystal silicon membranes using two different fabrication processes. We show that single-crystal silicon membranes are more uniform in their thickness and material quality than those of Si/sub x/N/sub y/ membranes. The single-crystal silicon membrane-based devices showed thickness and material uniformity across all the membranes of an array. This improvement eliminated nonuniform membrane resonance frequencies across an array as observed with Si/sub x/N/sub y/ membrane-based devices. Therefore, it should be possible to repeatably build devices and to predict their dynamic characteristics. Using the fabricated devices, we demonstrated water ejection at 470 kHz, 1.24 MHz, and 2.26 MHz. The corresponding droplet diameters were 6.5, 5, and 3.5 /spl mu/m, respectively.     

Role of rapid photothermal processing in process integration

The smaller dimension devices and larger scales of integration are demanding constant reduction of the macroscopic and microscopic defects in the manufacturing of silicon integrated circuits. Increasing capital investment in manufacturing is forcing us toward processes and equipment that are effective not only in reduction of the cost of ownership but can also increase the effectiveness of equipment of current as well as future applications. Rapid thermal processing (RTP) based on incoherent light as the source of energy is playing an important role in the manufacturing of 300 nm and larger diameter wafers. The dominance of ultraviolet and vacuum ultraviolet photons in RTP results in rapid photothermal processing (RPP). The results presented in this paper show that the materials and devices processed by RPP are better than those processed by other thermal processes. This paper discusses the manufacturing science, operating principles of RPP and experimental results supporting its role in future process integration     

Recent Progress in Functional Dye-Doped Liquid Crystal Devices

As a typical representative of dopants, organic functional dyes have demonstrated their significant roles in novel smart liquid crystal (LC) devices, and dye-doped LCs have also been a source of inspiration for scientists to design and fabricate stimuli-gated materials or devices for envisioned applications in a wide range of areas. In this review, the focus on dichroic dyes, fluorescent dyes, and photothermal dyes, and the recent progress of the LC devices employing these dyes as dopants are overviewed. The review highlights the developments of the novel LC devices doped with these dyes. The structures, designs, and applications of these devices are outlined. The underlying principles of dichroic dyes, fluorescent dyes, and photothermal dyes which are utilized as functional dopants in LC devices are first introduced. Subsequently, the novel developments of functional dye-doped LC devices in the application fields of smart windows, attenuators for augmented reality (AR) systems, color-changeable textiles, dichroic color filters, dual-mode circular polarizers, chirality detectors, optical limiters, switchable luminescent solar concentrators, multiple information encryption, anti-counterfeiting, photo-addressed transparent displays, circularly polarized luminescence, tunable lasers, and light-driven soft actuators are discussed. Finally, the challenge and the strategies for the future improvement of dye-doped LC devices are also discussed.     

Fundamental quantum 1/f noise in semiconductor devices

The quantum 1/f noise theory has been developed in the last two decades and has been applied to 1/f noise suppression in various electronic devices. This theory derives fundamental quantum fluctuations present in the elementary processes of physics at the level of the quantum mechanical cross sections and process rates. This paper demonstrates the basic simplicity of the theory with an elementary physical derivation followed by a short derivation of the conventional quantum 1/f effect in second quantization, for an arbitrary number of particles N defining the scattered current in the final state. A new derivation of the coherent quantum 1/f effect is also included. No adjustable parameters are present in the quantum 1/f theory. Practical applications to semiconductor materials, p-n junctions, SQUID's and quartz resonators are presented. Optimal design principles based on the quantum 1/f theory are described and explained     

Local Structural Heterogeneity and Electromechanical Responses of Ferroelectrics: Learning from Relaxor Ferroelectrics

Long‐range ordering of dipoles is a key microscopic signature of ferroelectrics. These ordered dipoles form ferroelectric domains, which can be reoriented by electric fields. Relaxor ferroelectrics are a type of ferroelectric where the long‐range ordering of dipoles is disrupted by cation disorder, exhibiting complex polar states with a significant amount of local structural heterogeneity at the nanoscale. They are the materials of choice for numerous devices such as capacitors, nonlinear optical devices, and piezoelectric transducers, owing to their extraordinary dielectric, electro‐optic, and electromechanical properties. However, despite their extensive applications in these devices, the origins of their unique properties are yet to be fully understood, hindering the design and exploration of new relaxor ferroelectric‐based materials. Herein, the complex polar states and applications of relaxor ferroelectrics are first introduced. Attention is then focused on their electromechanical properties, where the relationship between local structural heterogeneity and the extraordinary electromechanical properties is discussed. Based on the understanding of relaxor ferroelectrics, potential strategies to exploit the local structural heterogeneity to design ferroelectrics for drastically enhancing their electromechanical performances are also discussed. It is expected that this article will stimulate future studies on the important roles of local structural heterogeneity in improving the properties of various functional materials.     

微波真空电子器件用无氧铜材料的蒸发特性

作为微波真空电子器件的常用材料之一,无氧铜材料的蒸发特性会对微波真空电子器件的电性能产生影响。该文利用超高真空测试设备,研究了处理工艺对无氧铜材料的蒸发性能的影响,采用X射线测厚仪测试了蒸发的铜膜厚度,用扫描电镜(SEM)观测了无氧铜材料的表面形貌。结果表明表面宏观形貌粗糙度对无氧铜材料的蒸发性能影响不大,但处理工艺对蒸发性能影响很大;无氧铜材料经过酸洗后,会大大增加蒸发量;无氧铜材料经过烧氢处理,可降低蒸发量,而经过去油清洗并烧氢处理的无氧铜的蒸发量极低。对无氧铜材料进行了表面分析,发现无氧铜材料的真空蒸发性能与材料的表面形貌状态有关,当表面微观形貌比较光滑、无孔洞等缺陷时,无氧铜材料的真空蒸发量就少。     

Modeling and analysis of electrostatic force for robot handling offabric materials

Electrostatic force has received considerable interest in recent years for handling small objects in microsystems and microengineering applications, but little work has been carried out to study its use in handling large-size objects. This paper discusses the principles of a robotic electrostatic gripping device for the handling of large-size fabric plies. A theory is derived to describe the dynamic behavior of the charging/discharging processes of the gripping surface. Mathematical equations are developed to relate the dynamic performance of the gripping force to the device's design parameters and the properties of materials being handled. An automated experimental process is employed to validate the theory. The theoretical modeling and analysis of the gripping force has allowed optimization of the gripper's design parameters for practical materials handling applications. The design and construction of an electrostatic gripper for fabric handling in aerospace applications are discussed     

Flexible devices: from materials,architectures to applications

Flexible devices,such as flexible electronic devices and flexible energy storage devices,have attracted a significant amount of attention in recent years for their potential applications in modem human lives.The development of flexible devices is moving forward rapidly,as the innovation of methods and manufacturing processes has greatly encouraged the research of flexible devices.This review focuses on advanced materials,architecture designs and abundant applications of flexible devices,and discusses the problems and challenges in current situations of flexible devices.We summarize the discovery of novel materials and the design of new architectures for improving the performance of flexible devices.Finally,we introduce the applications of flexible devices as key components in real life.     

A review of thermoelectric refrigeration

The advantages of thermoelectric refrigeration, some of its possible applications and its principles of operation are briefly presented. The current state of the art in thermoelectric materials is discussed. The design problems in developing thermoelectric devices and some of the current techniques used to solve them are reviewed. Some information is provided on devices that have been built for the U. S. Navy and for commercial application.     

Lithium Extraction by Emerging Metal–Organic Framework-Based Membranes

Lithium is mainly extracted from brine and ores; however, current lithium mining methods require large amounts of chemicals, discharge many wastes, and can have serious environmental repercussions. Metal–organic framework (MOF)-based membranes have shown great potential in lithium extraction due to their uniform pore sizes, high porosities, and rich host–guest chemistry compared to other materials. In this review, the processes and disadvantages of current lithium extraction technologies are introduced. The structure features and corresponding design strategy of MOFs suitable for Li⁺ ion separations are presented. Following, recent advances of polycrystalline MOF membranes, mixed matrix membranes, and MOF channel membranes for lithium-ion separation are discussed in detail. Finally, opportunities for future developments and challenges in this emerging research field are presented.