Innovative Fabrication Research Articles

Unipolar resistive switching of solution synthesized ZnO nanorod with self-rectifying and Negative Differential Resistance effects

In this article, we report the first observation of unipolar memory effect in Al/ZnO NR/Al planar devices. ZnO nanorods were synthesized using facile solution route at room temperature. The synthesized nanorods were characterized by X-ray diffraction and scanning electron microscope. Using the synthesized ZnO nanorods two terminal planar devices were fabricated with lithographically defined metal contacts. The constructed metal-ZnO-metal devices have exhibited unipolar resistive memory characteristics with rectification and NDR effects. Mechanism for the unipolar switching has been proposed based on the formation and rupture of AlOx interlayer in the metal-semiconductor interface. The simultaneous occurrence of rectification and NDR effects with switching property has also been explained. This article brings an innovative and easy fabrication of unipolar resistive switching devices.

Green Leather for Ethical Consumers in China and Korea: Facilitating Ethical Consumption with Value–Belief–Attitude Logic

Using an innovative fabrication technique, eco-friendly faux leather (EFFL) has been newly developed as a green leather alternative for the Chinese and Korean markets. Value–belief–attitude logic drawn from the heuristic-systemic model (Zuckmand and Chaiken in Psychol Mark 15(7):621–642, 1998) and value–belief–norm theory (Stern et al. in Environ Behav 27(6):723–743, 1995) is proposed to explicate the consumer acceptance attitudes toward the EFFL product. The findings from the multi-group structural equation modeling analysis of online data (n = 600) support the relevancy of VBA logic in which utilitarian and hedonic value motivate pro-environmental belief, and the EFFL product attributes significantly mediate belief and positive attitude toward the EFFL product. The discrepancies across two countries and two age cohorts are noteworthy when pro-environmental belief and product-related information lead to different consumer VBA processes in specific market segments. This study presents insights which provide novel opportunities for managerial implementations and theoretical advancements in eco-friendly related subjects and issues.

Flexible piezoelectric thin-film energy harvesters and nanosensors for biomedical applications.

The use of inorganic-based flexible piezoelectric thin films for biomedical applications has been actively reported due to their advantages of highly piezoelectric, pliable, slim, lightweight, and biocompatible properties. The piezoelectric thin films on plastic substrates can convert ambient mechanical energy into electric signals, even responding to tiny movements on corrugated surfaces of internal organs and nanoscale biomechanical vibrations caused by acoustic waves. These inherent properties of flexible piezoelectric thin films enable to develop not only self-powered energy harvesters for eliminating batteries of bio-implantable medical devices but also sensitive nanosensors for in vivo diagnosis/therapy systems. This paper provides recent progresses of flexible piezoelectric thin-film harvesters and nanosensors for use in biomedical fields. First, developments of flexible piezoelectric energy-harvesting devices by using high-quality perovskite thin film and innovative flexible fabrication processes are addressed. Second, their biomedical applications are investigated, including self-powered cardiac pacemaker, acoustic nanosensor for biomimetic artificial hair cells, in vivo energy harvester driven by organ movements, and mechanical sensor for detecting nanoscale cellular deflections. At the end, future perspective of a self-powered flexible biomedical system is also briefly discussed with relation to the latest advancements of flexible electronics.

Stronger, Smarter, Softer: Next-Generation Wearable Robots

Exosuits show much promise as a method for augmenting the body with lightweight, portable, and compliant wearable systems. We envision that such systems can be further refined so that they can be sufficiently low profile to fit under a wearer's existing clothing. Our focus is on creating an assistive device that provides a fraction of the nominal biological torques and does not provide external load transfer. In early work, we showed that the system can substantially maintain normal biomechanics and positively affect a wearer's metabolic rate. Many basic fundamental research and development challenges remain in actuator development, textile innovation, soft sensor development, human-machine interface (control), biomechanics, and physiology, which provides fertile ground for academic research in many disciplines. While we have focused on gait assistance thus far, numerous other applications are possible, including rehabilitation, upper body support, and assistance for other motions. We look forward to a future where wearable robots provide benefits for people across many areas of our society.

50 Hz deuterium pellet injector for EAST tokamak

A new high frequency pellet injector has been developed for edge localized mode mitigation and plasma fuelling of the EAST tokamak. The pellet injector consists of two independent modules operating at 1–25Hz. Both modules are equipped with screw extruders cooled by liquid helium for solid deuterium ice production at steady state mode. An innovative pellet fabrication and acceleration system has been designed and applied to reduce gas load on the extruders in 4–5 times and to increase the pellet injection reliability. Pellets of 1.5mm diameter and 1.5mm length were injected at 250±50m/s velocity at 25Hz with reliability over 93% using one module in preliminary tests. Two modules working in turn are under tests now. It is anticipated they will be able to inject pellets at 50Hz after further technical improvements in near future.

Professional women’s thoughts about sustainable clothing: Eco-fashion goes business?

Abstract This article discusses the significant role of sustainable consumption in postmodern societies and the apparent ‘sustainable fashion gap’ in the priorities of consumers who are interested in sustainable issues in Germany. Drawing on the opinions of female academic employees from universities and managers from the private sector, this article will outline why consumers in Germany do not award sustainable clothing the same status as products in use in daily life in terms of sustainability. In the academic debate a negative image of eco-clothing, which developed in the 1970s, is considered to be responsible for such situation. The previous eco-clothing won a reputation by consumers as unfashionable and an ‘eco-frumpy-look’ and influenced its acceptance negatively. In spite of ecological textile innovations and the expansion of clothing ranges, consumption of sustainable clothing has not generally improved in recent decades. The survey fleshes out that the current low acceptance of sustainable fashion is not due to a supposedly negative image of ecological fashion but because of structural problems within the production and consumption processes as well as an inadequate product range which does not take gender constructs into account. The old clichés of eco-clothing no longer apply, but there are new problems relevant to the production and consumption of sustainable clothing. The article discusses furthermore the representation of sustainable clothing in the catalogues and fashion magazines of sustainable producers.

Sol–Gel Route Toward Efficient and Robust Distributed Bragg Reflectors for Light Management Applications

The optimization of functional optical devices requires the appropriate control of light propagation, which can be achieved by using engineered dielectric structures. Innovative materials combination and fabrication strategies are required to achieve a robust gain in performance without impacting manufacturing complexity and cost. In the present work, a novel liquid‐based approach is proposed for the simple and scalable fabrication of highly efficient and robust optical multilayer dielectric coatings. In particular, a sol–gel process is developed that enables the fabrication of large‐area distributed Bragg reflectors (DBR) integrating macroporous materials of controlled closed porosity. The DBRs have a very high index contrast, excellent and tunable optical properties, and high stability of performance and structural integrity with respect to crack formation and delamination, even against harsh ageing tests or solvent exposure. The potential of this approach to be integrated within existing optoelectronic architectures is demonstrated through the integration of a DBR structure as a back reflector in an amorphous silicon solar cell (a‐Si:H), resulting in a significant increase in light absorption, photocurrent, and overall efficiency. This opens the way towards simple dielectric engineering of robust photoactive devices based on the versatile use of liquid routes for the deposition of structured dielectric coatings.

Innovative fabrication of photoelectrodes for solar water splitting

Innovative fabrication of photoelectrodes for solar water splitting

Design of a macroalgae amperometric biosensor; application to the rapid monitoring of organophosphate insecticides in an agroecosystem

The immobilization of enzymes onto transducer support is a mature technology and has been successfully implemented to improve biocatalytic processes for diverse applications. However, there exists still need to design more sophisticated and specialized strategies to enhance the functional properties of the biosensors. In this work, a biosensor platform based on innovative fabrication strategy was designed, and employed for the detection of organophosphate (OP) in natural waters. The biosensor was prepared by incorporating acetylcholinesterase enzyme (AChE) to the graphite paste modified with tetracyanoquinodimethane (TCNQ) mediator, along with the use of a macroalgae (Cladaphropsis membranous) as a functional immobilization support. The novel immobilization design resulted in a synergic effect, and led to enhanced stability and sensitivity of the biosensor. The designed biosensor was used to analyze methyl parathion OP insecticide in water samples collected from a demonstrably contaminated lake of São Luis Island, Maranhão, Northeast of Brazil. Water analysis revealed that the aquatic ecosystem was polluted by sub-ppm concentrations of the OP insecticide, and a good correlation was found between values obtained through biosensor and GC–MS techniques. Our results demonstrated that macroalgae-biosensor could be used as a low-cost and sensitive screening method to detect target analyte.

Innovative Nanoimprint-Assisted Fabrication of Anodic Aluminum Oxide

Anodic aluminum oxide (AAO) templates possess highly-ordered nanoporous structures, with advantages such as high aspect ratio. However, there are limits to control the growth of the traditional AAO arrays, such as interpore distance, pore sizes and densities. In this study, we introduce an innovative nanoimprint process guided AAO fabrication to overcome these limitations of the traditional AAO arrays.

Three-dimensional polymeric microtiles for optically-tracked fluidic self-assembly

Self-assembly (SA) is a bio-inspired key coordination mechanism for swarms of intelligent agents as well as a pervasive bottom-up methodology for the fabrication of heterogeneous micro- and nanosystems. Analytical studies of SA at small scales are therefore highly relevant for many technological applications. In this paper we present an innovative design and fabrication process for three-dimensional polymeric microtiles conceived as passive vehicles to investigate the dynamics of fluidic SA at sub-millimeter scale. The microtiles are fabricated out of the superposition of two structural SU-8 layers featuring chiral copies of the same centro-symmetric pattern. They can coordinate laterally in water independently of their vertical orientation to form close-packed square lattice clusters. The microtiles embed a central marker enabling the real-time optical tracking and automated closed-loop control of their fluidic SA. The fabrication process makes use of a thick sacrificial copper layer and allows the wafer-level batch production of tens of thousands of microtiles, in line with the massively parallel nature of SA.

Additive Manufacturing: Making Imagination the Major Limitation

Additive manufacturing (AM) refers to an advanced technology used for the fabrication of three-dimensional near-net-shaped functional components directly from computer models, using unit materials. The fundamentals and working principle of AM offer several advantages, including near-net-shape capabilities, superior design and geometrical flexibility, innovative multi-material fabrication, reduced tooling and fixturing, shorter cycle time for design and manufacturing, instant local production at a global scale, and material, energy, and cost efficiency. Well suiting the requests of modern manufacturing climate, AM is viewed as the new industrial revolution, making its way into a continuously increasing number of industries, such as aerospace, defense, automotive, medical, architecture, art, jewelry, and food. This overview was created to relate the historical evolution of the AM technology to its state-of-the-art developments and emerging applications. Generic thoughts on the microstructural characteristics, properties, and performance of AM-fabricated materials will also be discussed, primarily related to metallic materials. This write-up will introduce the general reader to specifics of the AM field vis-à-vis advantages and common techniques, materials and properties, current applications, and future opportunities.

Special Issue on Robotics for Innovative Industry and Society

Robotics has become one of the most important automation technologies for industry and society. Robot components such as actuators and sensors, together with mechanisms and control systems, are being more and more combined with intelligent sensors in innovative industry design and fabrication. Robot technology is being applied in such fields as welfare, education, agriculture, and energy. Robot technology for welfare and nursing is being promoted by the government to increase lifestyle creativity as society ages. This special issue focuses on robotics in fields from manufacturing industries to societal needs. Papers ranging from robotics theory to robot application have been invited. Among the topics covered are robot mechanisms, robot components, actuators, sensors, and controllers, robot control theory, robotic systems, energy saving, industrial applications, automation, vehicles, entertainment, medicine, welfare and nursing applications, and robotics education. The 15 papers presented in this issue include actuators such as rubber artificial muscles or phase-change actuators, pneumatics, power assist devices such as assist glove and upper-limb assist devices, robotic suits, sensor fusion, omnidirectional locomotion, underwater robots, force display apparatuses, meal assistant robots, manufacturing applications of parallel-link mechanisms, surface polishing, and agricultural applications. These papers bring readers the latest state-of-the-art robot technologies useful in everything from analysis and design to control and applications in innovative industries. We thank the authors for their invaluable contributions and the reviewers for their advice – all of which have made this special issue both informative and entertaining.

3 kV Normally-Off 4H-SiC Buried Gate Static Induction Transistors (SiC-BGSITs)

3 kV normally-off SiC-buried gate static induction transistors (SiC-BGSITs) were fabricated by using an innovative fabrication process that was used by us previously to fabricate 0.7–1.2 kV SiC-BGSITs. The fabricated device shows the lowest specific on-resistance of 9.16 mΩ·cm2, compared to all other devices of the same class. The threshold voltage of this device was 1.4 V at room temperature and was maintained at values more than 1 V with normally-off characteristics at 200 °C. The device can block drain voltage of 3 kV with a leakage current density of 6.9 mA/cm2.

Electronic Coolers Based on Superconducting Tunnel Junctions: Fundamentals and Applications

Thermo-electric transport at the nano-scale is a rapidly developing topic, in particular in superconductor-based hybrid devices. In this review paper, we first discuss the fundamental principles of electronic cooling in mesoscopic superconducting hybrid structures, the related limitations and applications. We review recent work performed in Grenoble on the effects of Andreev reflection, photonic heat transport, phonon cooling, as well as on an innovative fabrication technique for powerful coolers.

Nano-engineering of three-dimensional core/shell nanotube arrays for high performance supercapacitors

Large-scale arrays of core/shell nanostructures are highly desirable to enhance the performance of supercapacitors. Here we demonstrate an innovative template-based fabrication technique with high structural controllability, which is capable of synthesizing well-ordered three-dimensional arrays of SnO2/MnO2 core/shell nanotubes for electrochemical energy storage in supercapacitor applications. The SnO2 core is fabricated by atomic layer deposition and provides a highly electrical conductive matrix. Subsequently a thin MnO2 shell is coated by electrochemical deposition onto the SnO2 core, which guarantees a short ion diffusion length within the shell. The core/shell structure shows an excellent electrochemical performance with a high specific capacitance of 910 F g−1 at 1 A g−1 and a good rate capability of remaining 217 F g−1 at 50 A g−1. These results shall pave the way to realize aqueous based asymmetric supercapacitors with high specific power and high specific energy.

Innovative fabrication of a Au nanoparticle-decorated SiO2 mask and its activity on surface-enhanced Raman scattering

Surface-enhanced Raman scattering (SERS) utilizing the well-defined localized surface plasmon resonance (LSPR) of Ag and Au nanoparticles (NPs) under resonant irradiation has emerged as a promising spectroscopy technique for providing vibrational information on trace molecules. The Raman scattering intensity from molecules close to the surface of these finely divided metals can be significantly enhanced by a factor of more than 10(6). In addition to the high sensitivity, the reproducibility of the SERS signal is also an important parameter for its reliable application. In this work, we report on the innovative and facile fabrication of a Au NP-decorated SiO2 mask coated on indium tin oxide (ITO) glass as a SERS array substrate. First, a highly ordered porous SiO2 mask with pore sizes of 350 nm in diameter and wall thickness of 60 nm was deposited on ITO glass by using spin coating. Then, Au NPs were controllably decorated into the pores of the conductive ITO glass-bottomed SiO2 mask by using sonoelectrochemical deposition-dissolution cycling (SEDDC). Experimental results indicate that the SERS effect of Rhodamine 6G (R6G) observed on this developed substrate increases with an increase in the deposition time of Au NPs in SEDDC. The corresponding optimal enhancement factor (EF) that is obtained is ca. 6.5 × 10(7). Significantly, this system achieves an optimal reproducibility under a medium-length deposition time of Au NPs in SEDDC with a relative standard deviation (RSD) of 12% for measurements of five spots on different areas. The low RSD of the SERS signal and the large EF suggest that the developed array system can serve as an excellent spectroscopy platform for practical applications in analytical chemistry.

C-Si Solar Cells based on Laser-processed Dielectric Films

This paper shows an innovative and low temperature fabrication technology for crystalline silicon (c-Si) solar cells where the highly-doped regions are punctually defined through laser processed dielectric films. Phosphorus-doped silicon carbide stacks (SiCx(n)) and aluminium oxide/silicon carbide (Al2O3/SiCx) stacks are used for the creation of n+ and p+ regions respectively. These films provide excellent surface passivation on both n- and p-type substrates with effective surface recombination velocity below 20cm/s. Moreover, a wide laser parameter window for laser processing them leads to low recombination highly-doped regions that show emitter saturation current densities of 21 and 113 fA/cm2 for n+ and p+ emitters respectively. All this is combined in the DopLa (Doped by Laser) cell structure whose fabrication process can be reduced to wafer cleaning, film depositions, laser processing and metallization. As a proof of concept, 1×1 cm2 solar cells were finished on both p- and n-type substrates with promising results. The analysis of loss mechanisms shows that optical losses and technological issues in the translation of surface passivation from the solar cell precursors to the final device are limiting efficiency. Both are not inherent to DopLa structure and suggest room for improvement in these devices. On the other hand, the crucial role played by ohmic losses in the proposed structure is identified. These ohmic losses arise from the fact that both base contacts and emitter regions are defined in point-like patterns. Firstly, base contacts are defined in a 1mm pitch square matrix introducing additional series resistance that can be reduced by using low resistivity substrates. Secondly, the emitter consists of laser processed local diffusions with an inversion layer emitter in-between characterized by very high sheet resistances. The ohmic losses introduced by this induced emitter are closely linked to the fixed charge density located at the dielectric/c-Si interface. As a result, we conclude that low resistivity n-type substrates fit better to DopLa cell concept because emitters are based on Al2O3/SiCx stacks which have higher fixed charge density, i.e. inversion layer emitters with lower sheet resistances, than their SiCx(n) counterparts.

Non Destructive Techniques for the Impact Damage Investigation on Carbon Fibre Laminates

Abstract Ultra sound technique (US), thermography and holography were adopted to investigate the delamination in carbon fibre laminates after low velocity impact loads. The scope was to investigate the ability of new tools in giving information about internal damage on composites. The carbon laminates were fabricated by a new vacuum assisted technology, labelled as “pulsed infusion”. The efficiency of this innovative fabrication technology was studied too, comparing the delamination extensions with the measurements from literature on impacted autoclave cured laminates.

Polymeric Infrared Compatible Microfluidic Devices for Spectrochemical Analysis

An innovative fabrication method is presented that affords the combination of polydimethyl-siloxane (PDMS) microfluidic technology with vibrational spectroscopy. PDMS devices are produced with uniform thicknesses ranging from 25 to 400 μm. The optical characteristics of the microfluidic devices in the mid-infrared are reported. The broad utility of this approach is demonstrated through IR imaging of flows in functional gradient generators and flow-focusing devices.