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1 – 10 of 362Ehsan Saeedi, Samuel Kim and Babak A. Parviz
The paper's aim is to present a method for integrating high‐performance circuit components onto flexible substrates using self‐assembly. The basic process of self‐assembly at the…
Abstract
Purpose
The paper's aim is to present a method for integrating high‐performance circuit components onto flexible substrates using self‐assembly. The basic process of self‐assembly at the micrometer‐scale is reviewed and recent work in building functional parts such as silicon transistors and compound semiconductor light emitting diodes, as well as their integration onto flexible plastic templates, is reported.
Design/methodology/approach
A micron‐scale self‐assembly method was used for building flexible circuits. In micron‐scale self‐assembly, functional micro‐components are independently microfabricated and subsequently allowed to self‐assemble on a template with electrical interconnects and corresponding binding sites in a fluid.
Findings
The self‐assembly process can achieve heterogeneous integration with a potentially very high yield. Successful assembly of functional micro‐components such as LEDs and transistors on plastic has been demonstrated.
Originality/value
The paper demonstrates fabrication techniques for free‐standing micro‐components with novel designs, low‐temperature fabrication on thin plastic sheets, and using capillary‐gravity‐based self‐assembly for the integration of crystalline inorganic semiconductor components onto unconventional substrates such as flexible polymers.
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The purpose of this paper is to provide a review of recent progress in self‐assembly technology, principally in the microelectronics context.
Abstract
Purpose
The purpose of this paper is to provide a review of recent progress in self‐assembly technology, principally in the microelectronics context.
Design/methodology/approach
First, the paper discusses the application of nanoscale self‐assembly techniques to microelectronic and related components and then considers research involving larger devices.
Findings
The paper shows that a range of self‐assembly techniques is being used to fabricate both production and experimental microelectronic devices, often with the aim of developing alternatives to copper wire interconnects. Other, experimental self‐assembly techniques are being developed for the packaging and mounting of microelectronic components on substrates.
Originality/value
Provides a useful, detailed review of the use of self‐assembly techniques at the nanoscale, microscale and macroscale.
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N.B. Crane, J. Tuckerman and G.N. Nielson
Additive manufacturing (AM) offers substantial flexibility in shape, but much less flexibility in materials and functionality – particularly at small size scales. A system for…
Abstract
Purpose
Additive manufacturing (AM) offers substantial flexibility in shape, but much less flexibility in materials and functionality – particularly at small size scales. A system for automatically incorporating microscale components would enable the fabrication of objects with more functionality. The purpose of this paper is to consider the potential of self‐assembly to serve as an automated programmable integration method. In particular, it addresses the ability of random self‐assembly processes to successfully assemble objects with high performance despite the possibility of assembly errors.
Design/methodology/approach
A self‐assembled thermoelectric system is taken as a sample system. The performance expectations for these systems are then predicted using modified one‐dimensional models that incorporate the effects of random errors. Monte‐Carlo simulation is used to predict the likely performance of self‐assembled thermoelectric systems and evaluate the impact of key process and system design parameters.
Findings
While assembly yield can drop quickly with increasing numbers of assembled parts, large functional assemblies can be constructed by arranging components in parallel to provide redundancy. In some cases, the performance losses are minimal. Alternatively, sensing can be incorporated to identify perfect assemblies. For small assemblies, the probability of perfection may be high enough to achieve an acceptable assembly rate. Small assemblies could then be combined into larger functional systems.
Originality/value
The paper identifies two strategies that can guide the development of AM processes that incorporate miniature components to increase the system functionality. The analysis shows that this may be possible despite significant errors in the self‐assembly process because systems may be tolerant of significant assembly errors.
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The purpose of this paper is to review recent developments in micro‐scale assembly technologies, primarily in the context of microsystems based on three‐dimensional (3D…
Abstract
Purpose
The purpose of this paper is to review recent developments in micro‐scale assembly technologies, primarily in the context of microsystems based on three‐dimensional (3D) micro‐electromechanical systems (MEMS) and micro‐opto‐electromechanical systems (MOEMS) technologies.
Design/methodology/approach
Following a brief introduction, this paper first discusses the problems associated with the assembly of micro‐components and then considers the role of robots and self‐assembly technologies. This is followed by a brief summary and conclusion.
Findings
Experimental robotic systems have been developed and used for the assembly of a wide range of MEMS and MOEMS components. Various self‐assembly technologies offer prospects for massively parallel microassembly but have yet to achieve the success of the robotic approach. Some work has sought to combine the best feature of both approaches but as yet, no technologies have been developed that can rapidly, accurately and cost‐effectively assemble micro‐components into hybrid 3D MEMS/MOEMS devices in a true production environment.
Originality/value
This paper provides a detailed review of recent progress in the robotic and self‐assembly of micro‐components.
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Zhifang Wang, Quanzhen Huang and Jianguo Yu
In this paper, the authors take an amorphous flattened air-ground wireless self-assembling network system as the research object and focus on solving the wireless self-assembling…
Abstract
Purpose
In this paper, the authors take an amorphous flattened air-ground wireless self-assembling network system as the research object and focus on solving the wireless self-assembling network topology instability problem caused by unknown control communication faults during the operation of this system.
Design/methodology/approach
In the paper, the authors propose a neural network-based direct robust adaptive non-fragile fault-tolerant control algorithm suitable for the air-ground integrated wireless ad hoc network integrated system.
Findings
The simulation results show that the system eventually tends to be asymptotically stable, and the estimation error asymptotically tends to zero with the feedback adjustment of the designed controller. The system as a whole has good fault tolerance performance and autonomous learning approximation performance. The experimental results show that the wireless self-assembled network topology has good stability performance and can change flexibly and adaptively with scene changes. The stability performance of the wireless self-assembled network topology is improved by 66.7% at maximum.
Research limitations/implications
The research results may lack generalisability because of the chosen research approach. Therefore, researchers are encouraged to test the proposed propositions further.
Originality/value
This paper designs a direct, robust, non-fragile adaptive neural network fault-tolerant controller based on the Lyapunov stability principle and neural network learning capability. By directly optimizing the feedback matrix K to approximate the robust fault-tolerant correction factor, the neural network adaptive adjustment factor enables the system as a whole to resist unknown control and communication failures during operation, thus achieving the goal of stable wireless self-assembled network topology.
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Zhichuang Qi, Jingshan Chen, Zhangmi Huang, Chunyan Hu and Baojiang Liu
This paper aims to prepare Poly(Styrene-Butyl acrylate-Methacrylic acid) @Poly Gallic acid-Fe3+ photonic crystal composite inks [P(St-BA-MAA)@PGA-Fe3+ PCCI, @ means the PGA-Fe3+…
Abstract
Purpose
This paper aims to prepare Poly(Styrene-Butyl acrylate-Methacrylic acid) @Poly Gallic acid-Fe3+ photonic crystal composite inks [P(St-BA-MAA)@PGA-Fe3+ PCCI, @ means the PGA-Fe3+ is loaded on the microspheres] and construct noniridescent structural colors on fabric substrates, with the goal of improving the visibility of structural colors.
Design/methodology/approach
P(St-BA-MAA)@PGA-Fe3+ PCCI were prepared by coating P(St-BA-MAA) microspheres with a metal-polyphenol network formed by gallic acid (GA, C7H6O5) and Fe3+. The assembly effects of the inks were explored under different conditions, including pH, temperature, concentration and surface tension. The optimal self-assembly conditions of the inks were determined using the controlled variable method.
Findings
The results demonstrated the successful preparation of P(St-BA-MAA)@PGA-Fe3+ PCCI. The metal polyphenol network film composed of GA and Fe3+ was successfully coated on the surface of P(St-BA-MAA) seed microspheres. The assembly mechanism of the inks was investigated, indicating that at a diethylene glycol (DEG, C4H10O3) concentration of 0.3 wt% and pH of 7, bright noniridescent structural colors could be formed on fabric surfaces after self-assembly by PCCI at 60 °C for 10 min. Furthermore, the mechanical fastness of the structural colors was enhanced due to the adherence of the soft shell composed of P(St-BA-MAA) and GA.
Originality/value
Utilizing a cost-effective approach and a diverse array of readily available raw materials, we have successfully prepared P(St-BA-MAA)@PGA-Fe3+ PCCI, which boasts superior performance and offers fabrics a range of unique coloring styles. This innovation paves the way for potential applications of structural colors in practical production, thereby broadening their realm of utility.
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The purpose of this study is to modify the FDM 3D printer to print with polystyrene (PS) microspheres as the printing material, thus enabling bottom-up structural color printing…
Abstract
Purpose
The purpose of this study is to modify the FDM 3D printer to print with polystyrene (PS) microspheres as the printing material, thus enabling bottom-up structural color printing and evaluating structural color printing.
Design/methodology/approach
This study chose a range of different heated bed temperatures to determine a suitable temperature for accelerating the self-assembly of photonic crystals and printing structural colors on various substrates. In addition, this study enhanced the structural color by doping PS microspheres with different contents of Acid Black 210 dye and evaluated the color-enhanced structural color by eye and spectrophotometer under different light sources.
Findings
The results show that the modified 3D printer can be used for structural color printing, and 50°C is determined as the heated bed temperature. There are significant differences in structural colors when printing under different color backgrounds and material substrates, and corresponding suitable substrates should be selected according to the application. The doping of PS microspheres with varying contents of dye results in different color levels of structural color. As with pigment colors, the visual perception of structural color varies when viewed under different light sources.
Originality/value
This paper proposes to print structural colors low-costly, analyze structural colors under substrate and light source conditions, and expand the structural color gamut by enhancing structural colors, which has positive implications for further research on structural colors as printing colors.
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Lingyun Cao, Shuaibin Ren, ZhengHao Zhou, Xuening Fei and Changliang Huang
This study aims to fabricate a cool phthalocyanine green/TiO2 composite pigment (PGT) with high near-infrared (NIR) reflectance, good color performance and good heat-shielding…
Abstract
Purpose
This study aims to fabricate a cool phthalocyanine green/TiO2 composite pigment (PGT) with high near-infrared (NIR) reflectance, good color performance and good heat-shielding performance under sunlight and infrared irradiation.
Design/methodology/approach
With the help of anionic and cationic polyelectrolytes, the PGT composite pigment was prepared using a layer-by-layer assembly method under wet ball milling. Based on the light reflectance properties and color performance tested by ultraviolet-visible-NIR spectrophotometer and colorimeter, the preparation conditions were optimized and the properties of PGT pigment with different assembly layers (PGT-1, PGT-3, PGT-5 and PGT-7) were compared. In addition, their heat-shielding performance was evaluated and compared by temperature rise value for their coating under sunlight and infrared irradiation.
Findings
The PGT pigment had a core/shell structure, and the PG thickness increased with the self-assembly layers, which made the PGT-3 and PGT-7 pigment show higher color purity and saturation than PGT-1 pigment. In addition, the PGT-3 and PGT-7 pigment showed 11%–16% lower light reflectance in the visible region. However, their light reflectance in the NIR region was similar. Under infrared irradiation the PGT-5 and PGT-7 pigment coating showed 1.1°C–3.4°C and 1.3°C–4.7°C lower temperature rise value than PGT-1 pigment coating and physical mixture pigment coating, respectively. And under sunlight the PGT-3 pigment coating showed 1.5–2.6°C lower temperature rise value than the physical mixture pigment coating.
Originality/value
The layer-by-layer assembling makes the core/shell PGT composite pigment possess low visible light reflectance, high NIR reflectance and good heat-shielding performance.
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This feature article aims to review state-of-the-art developments in additive manufacture, in particular, 4D printing. It discusses what it is, what research has been carried out…
Abstract
Purpose
This feature article aims to review state-of-the-art developments in additive manufacture, in particular, 4D printing. It discusses what it is, what research has been carried out and maps potential applications and its future impact.
Design/methodology/approach
The article first defines additive manufacturing technologies and goes on to describe the state-of-the-art. Following which the paper examines several case studies and maps a trend that shows an emergence of 4D printing.
Findings
The case studies highlight a particular specialization within additive manufacture where the use of adaptive, biomimetic composites can be programmed to reshape, or have embedded properties or functionality that transform themselves when subjected to external stimuli.
Originality/value
This paper discusses the state-of-the-art of additive manufacture, discussing strategies that can be used to reduce the print process (such as through kinematics); and the use of smart materials where parts adapt themselves in response to the surrounding environment supporting the notion of self-assemblies.
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Abstract
Purpose
The purpose of this paper is to investigate the preparation process and the photoluminescent properties of poly‐(phenylene vinylene) (PPV)/polyvinyl alcohol (PVA)/Ag2S composite nanofibres.
Design/methodology/approach
A simple method coupling electrospinning technology and in situ self‐assembly was used to prepare PPV/PVA/Ag2S nanofibres from the solution containing precursory PPV, PVA and silver nitrate (AgNO3). The photoluminescent properties of the PPV/PVA/Ag2S composite nanofibres were characterised by fluorescence microscopy and eclipse fluorescence spectrophotometer.
Findings
The Ag2S nanoparticles were well dispersed in the PPV/PVA/Ag2S composite nanofibres, and their dimension was in the range of 10‐40 nm. Excessive doping of Ag2S nanoparticles will lead to rough and uneven fibres' surface.
Research limitations/implications
The size of Ag2S nanoparticles in the fibres was not uniform enough and the orientation of composite nanofibres was hardly controlled.
Practical implications
The coupling of electrospinning technology and in situ self‐assembly opened a new gate for preparing other nanoparticles doped composite nanofibres.
Originality/value
The in situ growing of Ag2S nanoparticles in PPV nanofibre improved the excellent properties of composite nanofibres. The morphology of composite nanofibres can be efficaciously controlled via adjusting the ratio between AgNO3 and polymer. The obtained PPV/PVA/Ag2S composite nanofibres will have potential applications in nano‐optoelectronic devices.
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