Mass Production Applications Research Articles

A Device for Rapid, Automated Trimming of Insect-Sized Flying Robots

Successful demonstrations of controlled flight in flying insect-sized robots (FIRs) $ 500 mg have all relied on piezo-actuated flapping wings because of unfavorable downward size scaling in motor-driven propellers. In practice, the mechanical complexity of flapping wings typically results in large torque bias variability about pitch and roll axes, leading to rapid rotation in free flight for vehicles that are not properly trimmed. Manual trimming by watching high-speed video is tedious and error-prone. In this letter, we introduce an alternative, a trimming device that uses feedback from motion capture cameras to determine and correct for bias torques. It does so using an automated feedback loop, without the need for any visual feedback from the user, or airborne flights which can damage the robot. We validated the device on two different robot flies. After trimming with our device, the robots both took off approximately vertically in open-loop and were able to hover in free flight under feedback control. Our system, therefore, reduces the time of essential yet time-consuming step in robot fly fabrication, facilitating their eventual mass production and practical application.

Entomopatogene nematode - prirodni neprijatelji štetnih insekata

In the programmes of biological control, a large number of different beneficial organisms are applied, including certain groups of nematodes. From the aspect of biocontrol measures, the most significant group of nematodes is entomopathogenic nematodes, which represents both natural and ecological solution for pest control management. The protection success relies on the specific-mutualistic relationship between nematodes and bacteria, where nematodes in its intestinal carries cells of a symbiotic bacterium that kills the host insect. Regarding nematode-related biological control, two families draw the most attention, Steinernematidae and Heterorhabditidae. Within family Steinernematidae, the genus Steinernema stands out, while within Heterorhabditidae the most important genus is Heterorhabditis. Entomopatogenic nematodes have been used to control numerous agricultural pests, which include insects of different orders such as: Lepidoptera, Siphonaptera, Diptera, Coleoptera, Blattodea, Orthoptera and Heteroptera. Entomopathogenic nematodes are characterized by numerous traits that make them extremely suitable biological control agents: wide host spectrum, active host seeking, killing the host within 48 hours, easy mass production and field application, long-term efficacy, compatibility with most chemicals and environmentally safe.

Progress in environmental behaviors and safety of ionic liquids

Ionic liquids are remarkable chemical compounds, which are widely used in catalysis, energy, material preparation, biochemical and pharmaceutical fields due to their non-volatile, non-flammable, designable structure and high stability. In 1914, the first ionic liquid [EtNH3][NO3] was reported, but that was very unstable in the air. With the explosion, the development of ionic liquids has gone through a long period of silence. Subsequently, with the synthesis of chloroaluminate ionic liquids, the development of ionic liquids has become rapid, from imidazole, quaternary ammonium, pyridine-type ionic liquids to currently highly concerned functional ionic liquids. With the mass production and wide application of ionic liquids, their health risks to the environment have also attracted considerable attention. Although ionic liquids are green, stable, non-volatile, and non-flammable, which would not cause atmospheric pollution, they might be exist in soil and water environment in the process of use, such as production, recovery and treatment. In this paper, the structures of ionic liquids were described, and the influence of ionic liquids structure on biological safety was analyzed. The migration and transformation behavior of ionic liquids in different environmental media and the possible influencing factors were discussed. The environmental behavior of ionic liquids in water and soil is a systematic project. Single toxicity data and environmental data cannot objectively evaluate it. At present, a few related safety numbers of ionic liquids are available, and we should pay greater attention to the safety research of toxicity, degradation and corrosiveness directly related to environmental protection. The effects of ionic liquids on microorganisms, aquatic organisms and terrestrial organisms were summarized. There is no uniformity in toxic activities exhibited by ionic liquids. Some of them demonstrate relatively low toxicity, whereas others impose significant inhibitory effects in various biological systems. Several researches have been aimed at finding relationships that link the ionic liquid structure to its toxicity. However, no general correlations have been discovered. According to the accumulated data, the effect factors of toxicity are including the length of alkyl side chain in the cation, the presence and nature of functional groups in the cation, the anion and cation nature; and interactions between anion and cation. Generally, there is a positive relationship between the alkyl side chain length and toxicity, and an inverse relationship between the relative number of oxygen atoms and toxicity. However, the toxicity of ionic liquids does not always comply with the above rules. The current chemical and biological degradation methods of ionic liquids were reviewed. It is necessary to choose safe and effective degradation methods according to the anions and cations of ionic liquids. Ionic liquids with short side chains should choose chemical degradation as far as possible, while ionic liquids with long alkyl side chains should give priority to biodegradation. In addition, the influences of ionic liquids’ structure on their degradation performance need to be systematically studied. In order to provide a basis for the development of low toxicity and biodegradable ionic liquids, it is also an important way to improve the safety of ionic liquids. This paper clarifies that further study on the environmental behavior, safety effects and degradation methods of ionic liquids is of high scientific value, which is great significance for objective evaluation of the potential of large-scale application of ionic liquids.

Fourier-transform spectrometer chip covering visible band on silica planar waveguide

To minimise a spectrometer maximally, using a micro-electro-mechanical system or planar waveguide chip, has aroused interest in both academia and industry. This is because a portable and inexpensive spectral analysis tool has tremendous potential in various applications including scientific exploration, industrial inspection, and environmental protection. Here, we design, fabricate, and characterise a Fourier-transform spectrometer (FTS) chip consisting of 101 Mach–Zehnder interferometers (MZIs) with gradually varying optical path differences on a silica planar waveguide platform, aiming to cover the entire visible band. To ensure a wide-band operation while simultaneously compressing the size of the chip, wide-bending arm waveguides that can support high-order modes in a short wavelength range are employed in the design of the MZI array. The experimental result of our FTS chip shows its ability to analyse the visible spectrum with a minimum resolution of better than 10 nm and to reproduce the original spectrum with an accuracy of less than 0.5 nm. The successful implementation of the FTS chip based on a matured and low-cost silica planar lightwave circuit process makes it quite promising to realise mass production and widespread application.

Ambient Synthesis of Single-Atom Catalysts from Bulk Metal via Trapping of Atoms by Surface Dangling Bonds.

Single-atom catalysts (SACs) feature the maximum atom economy and superior performance for various catalysis fields, attracting tremendous attention in materials science. However, conventional synthesis of SACs involves high energy consumption at high temperature, complicated procedures, a massive waste of metal species, and poor yields, greatly impeding their development. Herein, a facile dangling bond trapping strategy to construct SACs under ambient conditions from easily accessible bulk metals (such as Fe, Co, Ni, and Cu) is presented. When mixing graphene oxide (GO) slurry with metal foam and drying in ambient conditions, the M0 would transfer electrons to the dangling oxygen groups on GO, obtaining Mδ+ (0 < δ < 3) species. Meanwhile, Mδ+ coordinates with the surface oxygen dangling bonds of GO to form MO bonds. Subsequently, the metal atoms are pulled out of the metal foam by the MO bonds under the assistance of sonication to give M SAs/GO materials. This synthesis at room temperature from bulk metals provides a versatile platform for facile and low-cost fabrication of SACs, crucial for their mass production and practical application in diverse industrial reactions.

Hydrophilic Silver Nanoparticles Loaded into Niosomes: Physical-Chemical Characterization in View of Biological Applications.

Silver nanoparticles (AgNPs) are widely used as antibacterial agents and anticancer drugs, but often their low stability limits their mass production and broad applications. The use of niosomes as a carrier to protect and envelop AgNPs gives a new perspective to solve these problems. In this study, AgNPs were functionalized with sodium 3-mercapto-1-propanesulfonate (3MPS) to induce hydrophilic behavior, improving loading in Tween 20 and Span 20 niosomes (NioTw20 and NioSp20, respectively). Entrapment efficiency was evaluated by UV analyses and is around 1–4%. Dimensions were investigated by means of dynamic light scattering (DLS) (<2RH> = 140 ± 4 nm and <2RH> = 251 ± 1 nm respectively for NioTw20 + AgNPs and NioSp20 + AgNPs) and were compared with those by atomic force microscopy (AFM) and small angle X ray scattering (SAXS) analyses. Stability was assessed in water up to 90 days, and both in bovine serum and human serum for up to 8 h. In order to characterize the local structure of niosomes, SAXS measurements have been performed on Tween 20 and Span 20 empty niosomes and loaded with AgNPs. The release profiles of hydrophilic probe calcein and lipophilic probe Nile Red were performed in HEPES buffer and in human serum. All these features contribute to conclude that the two systems, NioTw20 + AgNPs and NioSp20 + AgNPs, are suitable and promising in the field of biological applications.

Eco‐Compatible Solvent‐Processed Organic Photovoltaic Cells with Over 16% Efficiency

Recent advances in nonfullerene acceptors (NFAs) have enabled the rapid increase in power conversion efficiencies (PCEs) of organic photovoltaic (OPV) cells. However, this progress is achieved using highly toxic solvents, which are not suitable for the scalable large-area processing method, becoming one of the biggest factors hindering the mass production and commercial applications of OPVs. Therefore, it is of great importance to get good eco-compatible processability when designing efficient OPV materials. Here, to achieve high efficiency and good processability of the NFAs in eco-compatible solvents, the flexible alkyl chains of the highly efficient NFA BTP-4F-8 (also known as Y6) are modified and BTP-4F-12 is synthesized. Combining with the polymer donor PBDB-TF, BTP-4F-12 shows the best PCE of 16.4%. Importantly, when the polymer donor PBDB-TF is replaced by T1 with better solubility, various eco-compatible solvents can be applied to fabricate OPV cells. Finally, over 14% efficiency is obtained with tetrahydrofuran (THF) as the processing solvent for 1.07 cm2 OPV cells by the blade-coating method. These results indicate that the simple modification of the side chain can be used to tune the processability of active layer materials and thus make it more applicable for the mass production with environmentally benign solvents.

PICOSECOND LASER MICROMACHINING OF SILICON WAFER: CHARACTERIZATIONS AND ELECTRICAL PROPERTIES

This work presents the feasibility of picosecond laser micromachining of polysilicon wafer. Surface topography, microstructure and residual stress of both as-received surface and laser-machined surface were analyzed carefully by confocal microscope, scanning electron microscope and Raman microscope. Moreover, electrical properties of laser-machined wafer have been investigated to examine the effect of laser micromachining on Si substrate via characterizations of resistivity and [Formula: see text] curves. The results show that the wafer thickness has been reduced up to 50%, while the depth of HAZ is less than 3[Formula: see text][Formula: see text]m, and compressive stress can be achieved at the laser-machined surface. Besides, laser micromachining causes little influence on electrical properties of wafer. This proof-of-concept process has the potential application in mass production of integrated circuit industry.

Capturing anharmonic and anisotropic natures in the thermotics and mechanics of Bi2Te3 thermoelectric material through an accurate and efficient potential

Force-field-(FF)-based molecular simulation is essential but challenging in the theoretical research of complex thermoelectric (TE) materials. As they are general and crucial in TE semiconductors, the structural natures of anharmonicity and anisotropy can help us understand the inherent relation between thermal and mechanical behavior, and therefore the reliability of FF studies can be assessed. In this paper, given prior knowledge of the structural, mechanical and thermal properties as well as the limitations and necessary approximations of the FF method, a feasible and detailed FF modeling scheme and simulation has been designed for Bi2Te3, which is a typical high-performance TE material. Using the complementary approach combining quasi-harmonic lattice and molecular dynamics, the obtained potential is systematically confirmed to be accurate and efficient for the prediction of anharmonic and anisotropic behavior in thermotics and mechanics over a wide temperature range compared with the present Bi2Te3 models. This reveals that the intrinsic anisotropy and anharmonicity can measure the asymmetry of crystal lattices and the interatomic force in the current state. In addition, the significant distinction of temperature-dependent anharmonic effects in different directions of Bi2Te3 stems from its layered hierarchical structure, in which weak van der Waals bonding will probably be the key structural factor in comprehensively improving performance for mass production and wearable application. This prior-knowledge-based FF study is also suggested as a bridge between the theoretical understanding of micro-mechanisms and the experimental measurement of TE material properties, leading to a general framework of molecular simulation for other complex energy materials.

Standard red green blue (sRGB) color representation with a tailored dual-resonance mode in metal/dielectric stacks

Lithography-free planar structures have been the subject of many studies on structural coloration in recent years because of mass production and large-area applications. Among them, the metal-insulator-metal (MIM) structure follows a subtractive color system. However, the limited gamut of this system hinders a wider application of reflective color filters. We demonstrate a planar metal-insulator-metal-insulator-metal (MIMIM) structure for a tunable dual-resonance mode, by combining each single-resonance mode in MIM structures. By controlling the resonance dips, we obtain standard red/green/blue (sRGB) in the standard color space for modern optical devices. The reflectance spectra, color representation, and fabricated samples verify the dual-resonance tunability and generation of sRGB colors.

Process Development of Radical Based Dry Clean for Advanced 3D NAND Fabrication

As semiconductor device scaling marching toward sub-5 nm logic, 128+ layers 3D NAND, and 1x nm DRAM, wafer surface cleaning and residue removal in nanoscale, high aspect ratio (AR) structures become increasingly critical. Dry plasma clean technologies based on reactive radicals are developed as alternatives for traditional wet clean applications with significant advantages in process extendibility and environmental friendliness. Here we report a novel inductively coupled remote plasma design for radical based dry clean applications. A high gas dissociation efficiency and a high radical density were achieved with controllable radical component, energy, and reactivity. Two applications, including residue clean in high aspect ratio channel holes and contact holes (AR ~ 50:1), are tailored for 3D NAND manufacturing. Complete removal of oxide and polymeric residues, smooth and pristine Si surface, and considerably reduce contact resistance can be simultaneously achieved with the customized clean chemistries. Applications in mass production have been accomplished.

Quasi-Isotropic and Pseudo-Ductile Highly Aligned Discontinuous Fibre Composites Manufactured with the HiPerDiF (High Performance Discontinuous Fibre) Technology.

Conventional composite materials reinforced with continuous fibres display high specific strength but have a number of drawbacks including: the elastic-brittle behaviour, difficulties in producing defect-free components of complex shape with high-volume automated manufacturing processes, and inherent lack of recyclability. Highly aligned, discontinuous fibre-reinforced composites (ADFRCs) are truly beneficial for mass production applications, with the potential to offer better formability and comparable mechanical properties with continuous fibre-reinforced composites. In previous publications, the High Performance Discontinuous Fibre (HiPerDiF) technology has been shown to offer the possibility to intimately hybridise different types of fibres, to achieve pseudo-ductile tensile behaviour, and remanufacture reclaimed fibres into high-performance recycled composites. However, to date, the work has been conducted with unidirectional (UD) laminates, which is of limited interest in engineering applications with mechanical stresses acting across many directions; this paper reports, for the first time, the mechanical behaviour of quasi-isotropic (QI) ADFRCs. When compared with randomly-oriented discontinuous fibre composites (RODFRCs), QI ADFRCs offer enhanced stiffness (+26%) and strength (+77%) with higher consistency, i.e., a reduction of the coefficient of variance from the 25% of RODFRCs to the 6% of ADFRCs. Furthermore, hybrid QI ADFRCs retain the pseudo-ductility tensile behaviour previously observed in unidirectional (UD) lay-up.

Ultrathin Polyamide Nanofiltration Membrane Fabricated on Brush-Painted Single-Walled Carbon Nanotube Network Support for Ion Sieving.

Recently, ultrathin polyamide nanofiltration membranes fabricated on nanomaterial-based supports have overcome the limitations of conventional supports and show greatly improved separation performance. However, the feasibility of the nanomaterial-based supports for large-scale fabrication of the ultrathin polyamide membrane is still unclear. Herein, we report a controllable and saleable fabrication technique for a single-walled carbon nanotube (SWCNT) network support via brush painting. The mechanical and chemical stability of the SWCNT network support were carefully examined, and an ultrathin polyamide membrane with thickness of ∼15 nm was successfully fabricated based on such a support. The obtained thin-film composite (TFC) polyamide nanofiltration membranes exhibited extremely high water permeability of ∼40 L m-2 h -1 bar-1, a high Na2SO 4 rejection of 96.5%, and high monovalent/divalent ion permeation selectivity and maintained highly efficient ion sieving throughout 48 h of testing. This work demonstrates a practical route toward the controllable large-scale fabrication of the TFC membrane with an SWCNT network support for ion and molecule sieving. This work is also expected to boost the mass production and practical applications of state-of-the-art membranes composed of one-dimensional and two-dimensional nanomaterials as well as the nanomaterial-supported TFC membranes.

Rapid Oxidation of the Hole Transport Layer in Perovskite Solar Cells by A Low-Temperature Plasma

Herein we report a strategy of rapid oxidation of the hole transport layer (HTL) in perovskite solar cells by using oxygen/argon mixture plasma. This strategy offers a promising approach for simple manufacturing, mass production, and industrial applications. Compared to the conventional process of overnight oxidation, only ~10 s of oxygen/argon mixture plasma treatment is enough for the solar cell devices with FTO/ETL/perovskite/HTL/Au structure demonstrating a high power conversion efficiency. It is found that the high concentration of atomic oxygen generated in plasma oxidizing the HTL improves the conductivity and mobility, and therefore the process time is considerably shortened. This novel approach is compatible with continuous mass production, and it is suitable for the fabrication of large-area perovskite solar cells in the future.

Hierarchically Structured Core-Shell Design of a Lithium Transition-Metal Oxide Cathode Material for Excellent Electrochemical Performance.

Tuning geometrical parameters of lithium-mixed transition-metal oxide (LiTM) cathode materials is a promising strategy for resource-efficient design of high-performance Li-ion batteries. In this paper, we demonstrate that simple and facile geometrical tailoring of the secondary microstructure of LiTM cathode materials without complex chemical modification or heterostructure engineering can significantly improve overall electrochemical performance of the active cathode materials. An optimized LiTM with a bimodal size distribution of primary particles inside the secondary particles exhibits a 53.8% increase in capacity at a high discharge rate (10 C) compared to a commerciallyavailable reference and comparable rate capability after 100charge/discharge cycles. The key concept of this approach is to maximize the beneficial effects arising from the controlled sizes of primary particles. Multimodal/multiscale microscopic characterizations based on electron tomography and scanning transmission electron microscopy, combined with electron energy-loss spectroscopy and energy-dispersive X-ray spectroscopy from the atomic level to the microscale level, were employed to elucidate structural origins of enhanced battery performance. This study paves the way for the resource-efficient microstructure design of LiTM cathode materials to maximize capacity and stability via simple adjustment of processing conditions, which is advantageous for mass-production applications.

Ultrathin multifunctional carbon/glass fiber reinforced lossy lattice metastructure for integrated design of broadband microwave absorption and effective load bearing

Microwave absorbers as an effective way to reduce microwave radiation in stealth technologies and electromagnetic compatibility have attracted great attentions recently. Herein, a novel multifunctional carbon fiber (CF)/glass fiber (GF) reinforced lossy lattice metastructure for broadband microwave absorption and effective load bearing is proposed for the first time based on the structural similarity of photonic crystal and lightweight mechanical lattice. The lossy lattice is fabricated with nano lossy composite composed of multiwall carbon nanotube (MWCNT) and spherical carbonyl iron (CI) particles to manipulate complex permittivity and complex permeability. Sub-wavelength effect and structural optimization are applied for the metastructure to extend −10 dB absorption bandwidth from 3.42 GHz to 19.73 GHz with thickness of 3.5 mm. With solid attachment of CF and GF, the metastructure achieves high average equivalent strength of 167.35 MPa and fracture strain of 5.45%. A long plastic stage of the metastructure is observed after GF fracture or GF delamination in three-point flexural test. The integrated design of microwave absorbing and mechanical properties make it promising for practical applications in mass production.

A fully defined static suspension culture system for large-scale human embryonic stem cell production

Human embryonic stem cells (hESCs) play an important role in regenerative medicine due to their potential to differentiate into various functional cells. However, the conventional adherent culture system poses challenges to mass production of high-quality hESCs. Though scientists have made many attempts to establish a robust and economical hESC suspension culture system, there are existing limitations, including suboptimal passage methods and shear force caused by dynamic stirring. Here, we report on an efficient large-scale culture system, which enables long-term, GMP grade, single-cell inoculation, and serial expansion of hESCs with a yield of about 1.5 × 109 cells per 1.5-L culture, while maintaining good pluripotency. The suspension culture system was enlarged gradually from a 100-mm dish to a 1.8-L culture bag with methylcellulose involvement to avoid sphere fusion. Under the optimal experimental protocol, this 3D system resolves current problems that limit mass production and clinical application of hESCs, and thus can be used in commercial-level hESC production for cell therapy and pharmaceutics screening in the future.

Flexible Electronics Based on Micro/Nanostructured Paper.

Over the past several years, a new surge of interest in paper electronics has arisen due to the numerous merits of simple micro/nanostructured substrates. Herein, the latest advances and principal issues in the design and fabrication of paper-based flexible electronics are highlighted. Following an introduction of the fascinating properties of paper matrixes, the construction of paper substrates from diverse functional materials for flexible electronics and their underlying principles are described. Then, notable progress related to the development of versatile electronic devices is discussed. Finally, future opportunities and the remaining challenges are examined. It is envisioned that more design concepts, working principles, and advanced papermaking techniques will be developed in the near future for the advanced functionalization of paper, paving the way for the mass production and commercial applications of flexible paper-based electronic devices.

Dyeing Your Hair with Graphene

In this issue of Chem, Huang and co-workers present an innovative hair-dyeing approach that uses water-based formulations of graphene oxide (GO) and its reduced form (rGO) to eliminate the use of toxic, small-molecule pigments, which are commonly used in black hair dyes. Notably, the high adhesion ability and flexibility of graphene not only led to durable and uniform coating but also imparted properties—such as antistatic performance and efficient heat and electrostatic charge dissipation—superior to those of conventional black dyes.

Multi-unit calibration rejects inherent device variability of chemical sensor arrays

Inherent sensor variability limits mass-production applications for metal oxide (MOX) gas sensor arrays because calibration for replicas of a sensor array needs to be performed individually. Recently, calibration transfer strategies have been proposed to alleviate calibration costs of new replicas, but they still require the acquisition of transfer samples. In this work, we present calibration models that can be extended to uncalibrated replicas of sensor arrays without acquiring new samples, i.e., general or global calibration models. The developed methodology consists in including multiple replicas of a sensor array in the calibration process such that sensor variability is rejected by the general model. Our approach was tested using replicas of a MOX sensor array in the classification task of six gases and synthetic air, presented at different background humidity and concentration levels. Results showed that direct transfer of individual calibration models provides poor classification accuracy. However, we also found that general calibration models kept predictive performance when were applied directly to new copies of the sensor array. Moreover, we explored, through feature selection, whether particular combinations of sensors and operating temperatures can provide predictive performances equivalent to the calibration model with the complete array, favoring thereby the existence of more robust calibration models.