Innovative Fabrication Techniques Research Articles

Interaction-tailored organization of large-area colloidal assemblies.

Colloidal lithography is an innovative fabrication technique employing spherical, nanoscale crystals as a lithographic mask for the low cost realization of nanoscale patterning. The features of the resulting nanostructures are related to the particle size, deposition conditions and interactions involved. In this work, we studied the absorption of polystyrene spheres onto a substrate and discuss the effect of particle–substrate and particle–particle interactions on their organization. Depending on the nature and the strength of the interactions acting in the colloidal film formation, two different strategies were developed in order to control the number of particles on the surface and the interparticle distance, namely changing the salt concentration and absorption time in the particle solution. These approaches enabled the realization of large area (≈cm2) patterning of nanoscale holes (nanoholes) and nanoscale disks (nanodisks) of different sizes and materials.

The development of polymeric biomaterials inspired by the extracellular matrix

The field of biomaterials science has exhibited astounding growth during the last half century. This growth can be attributed to a more thorough understanding of cellular behaviours, new mechanistic insights into cell–materials interactions, advances in polymer synthesis, and the development of innovative fabrication techniques. This progress has enabled biomaterials to transition from materials that fill in for damaged or diseased tissues to implants that actively work with biology to aid in the healing process. In this review, we will discuss several of these advances including emerging knowledge on mechanotransduction, the use of substrate topography in modulating cellular behaviour, and the incorporation of bioactive molecules to foster specific cellular adhesion, promote tissue morphogenesis, and enable biologically driven degradation. We will then consider future challenges and directions in the field.

A review on future planar transmission line

AbstractSubstrate Integrated Waveguide (SIW) is an emerging trend in planar technology. The SIW structure consists of two rows of conducting cylinders in a dielectric substrate. The average power-handling capacity of an SIW structure is primarily determined by its substrate materials and its geometric topology. The power-handling capability depends on the nature of SIW circuits. Microwave and millimeter wave components can be integrated on SIW. It acts as a bridge between planar and non-planar technology. By using innovative fabrication techniques, SIW technology combines the classical planar circuits and metallic waveguide. The animus of the study is to provide the idea on design and fabrication of SIW structures and comparison between different topologies used for size reduction and dominant mode bandwidth enhancement.

Crack-Photolithography for Membrane-Free Diffusion-Based Micro/Nanofluidic Devices.

Recent advances in controlling the cracking phenomena established a novel unconventional fabrication technique to generate mixed-scale patterns/structures with resolution and accuracy comparable to conventional nanofabrication techniques. Here, we adapt our previous cracking-assisted nanofabrication technique (called "crack-photolithography") relying on only the standard photolithography to develop micro/nanofluidic devices with greatly reduced time and cost. The crack-photolithography makes it possible not only to simultaneously produce micropatterns and nanopatterns with various dimensions but also to replicate both of the mixed-scale patterns in a high-throughput manner. Therefore, a microfluidic channel network can easily be fabricated with a nanochannel array that can function as a nanoporous membrane wherever necessary, which basically plays a key role in diffusion-allowed but convection-suppressed microfluidic devices. In addition, the nanochannel array can manipulate the transport of small molecules by adjusting its dimension and/or number at will, so that nanochannel-array-integrated micro/nanofluidic devices prove even more robust and accurate in diffusion control than conventional membrane-integrated microfluidic devices. As an application of such micro/nanofluidic devices, we employed synthetic bacterial cells and found that their genetic induction and expression are dominated by extracellular diffusive microenvironments that were completely engineered using the nanochannel array. Hence, the crack-photolithography could provide innovative fabrication techniques for unprecedented micro/nanofluidic devices that show substantial potential for a wide range of biological and chemical applications.

Novel self-assembly-induced 3D plotting for macro/nano-porous collagen scaffolds comprised of nanofibrous collagen filaments

This study proposes self-assembly-induced 3D plotting as an innovative solid freeform fabrication (SFF) technique for the production of macro/nano-porous collagen scaffolds, particularly comprised of nanofibrous collagen filaments. In this technique, collagen filaments deposited in a coagulation bath could be effectively gelled through the self-assembly of collagen molecules into fibrils, accordingly, enabling the 3-dimensional deposition of collagen filaments with a collagen nanofiber network. The unique macro/nano-structure could be structurally stabilized by dehydration process coupled with chemical cross-linking. The porous collagen scaffolds produced had 3-dimensionally interconnected macropores (~ 451×305μm in pore width) separated by nanoprous collagen filaments. In addition, the macro/nano-porous collagen scaffolds showed the tensile strength of~353kPa and compressive strength of~31kPa at a porosity of~95vol% and excellent in vitro biocompatibility, assessed using pre-osteoblast MC3T3-E1 cells.

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.

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.

Visible photoluminescence of nanometer-sized SiGe/Si heterostructure fabricated by ion implantation

An innovative fabrication technique for the nanometer-sized SiGe/Si heterostructure was developed in this study. Ge was induced in Si substrate by two-step ion implantation. The spherical SiGe nanoclusters are self-assembled in the Si substrate by subsequent rapid thermal annealing at 1,100 °C. The diameter of the spherical SiGe nanoclusters is 5–7 nm. Visible photoluminescence from this nanometer-sized SiGe/Si heterostructure at room temperature was investigated. We found three peak energies of visible luminescence spectra at 1.97, 2.13, and 2.16 eV, respectively. The luminescence intensity depends on the number of the nanoclusters and will be decreased because of the micro-defects around the heterostructure, which is discussed in detail.

Basic Principles for Rational Design of High‐Performance Nanostructured Silicon‐Based Thermoelectric Materials

Recently, nanostructured silicon-based thermoelectric materials have drawn great attention owing to their excellent thermoelectric performance in the temperature range around 450 °C, which is eminently applicable for concentrated solar thermal technology. In this work, a unified nanothermodynamic model is developed to investigate the predominant factors that determine the lattice thermal conductivity of nanocrystalline, nanoporous, and nanostructured bulk Si. A systematic study shows that the thermoelectric performance of these materials can be substantially enhanced by the following three basic principles: 1) artificial manipulation and optimization of roughness with surface/interface patterning/engineering; 2) grain-size reduction with innovative fabrication techniques in a controllable fashion; and 3) optimization of material parameters, such as bulk solid-vapor transition entropy, bulk vibrational entropy, dimensionality, and porosity, to decrease the lattice thermal conductivity. These principles may be used to rationally design novel nanostructured Si-based thermoelectric materials for renewable energy applications.

A new nanofiber fabrication technique based on coaxial electrospinning

In tissue engineering, nanofibrous scaffolds can achieve better biological responses than microfibrous scaffolds and electrospinning is a common method for producing fibrous scaffolds. However, not all biopolymers can be made into nanofibers through conventional electrospinning. The current investigation developed an innovative nanofiber fabrication technique based on coaxial electrospinning and used poly(hydroxybutyrate -co-hydroxyvalerate) (PHBV) as an example for achieving nanofibers. For obtaining PHBV nanofibers, core–shell structured fibers were fabricated first via coaxial electrospinning, with PHBV being the core and chitosan being the shell. The chitosan shell was then removed by washing electrospun scaffolds with water, leading to the formation of nanofibrous PHBV scaffolds. The PHBV nanofiber diameter was affected by the inner polymer (i.e., PHBV) solution concentration during coaxial electrospinning, which can be explained in terms of the coaxial electrospinning process and polymer solution viscosity. Compared to the approach of using a conductivity-enhancing salt in polymer solution to produce polymer nanofibers, the new technique not only eliminates the biocompatibility concerns but also provides a more effective way of reducing fiber diameters to the nano-size range.

Liquid foam dielectrics for high frequency integratable antennas

An innovative fabrication technique to create nominal height liquid foam substrate layer for integratable antennas is introduced. The liquid foam layer is intended to replace a Rohacell foam or air substrate, especially at millimeter-wave frequencies, where antenna designs require substrate layers less than a millimeter thick. The performance of hi-lo stacked patch antenna with 0.5-mm-thick layer of ECCOSTOCK FPH is presented. The 10-dB return loss bandwidth of the antenna is 18.2%, and the radiation patterns and gain are also presented and discussed.

Self-assembled GaAs islands on Si by droplet epitaxy

We presented an innovative fabrication technique for the self-assembly of GaAs islands on Si substrates by droplet epitaxy. The islands show highly tunable density (from 107 to some 109 islands/cm2) and size (from 75 to 250 nm), and small size dispersion (below 10%). The islands, made by single relaxed crystals with lattice parameters close to the GaAs bulk, show well defined shapes, with a high aspect ratio. The low thermal budget required for the island self-assembly, together with the high scalability of the process, make these islands good candidates for local artificial substrates or local strain sources with the required lattice parameters, band alignment, and crystalline quality as now required for the implementation of high quality devices on Si.

Horizontal Current Bipolar Transistor With a Single Polysilicon Region for Improved High-Frequency Performance of BiCMOS ICs

A new horizontal current bipolar transistor (HCBT) with a single polysilicon region and a CMOS gate polysilicon near the n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> emitter region is integrated with CMOS technology with the addition of two or three masks (three or four masking steps) and a small number of additional fabrication steps. The single-poly HCBT with an optimized collector exhibits f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of 51 and 61 GHz, respectively, and an f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> BV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CEO</sub> product of 173 GHz · V, which are the best reported HCBT characteristics to date and among the highest performance Si BJTs. An HCBT with only two additional masks to CMOS has f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of 43 and 53 GHz, respectively, and an f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> SV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CEO</sub> product of 120 GHz · V. The developed innovative fabrication techniques enable a very low-cost BiCMOS platform for wireless communication circuits.

Applications of Microelectromechanical Systems in Industrial Processes and Services

This paper presents a review of the current and future applications of microelectromechanical systems (MEMS) in the industrial sector. A historical perspective of the origin and development of MEMS is presented, as well as the traditional and innovative fabrication techniques. The process flow of computer-aided design and simulation is also discussed. After that, several of the most important applications of microsystems in the manufacturing and production sectors are enumerated and described. Two case examples are discussed in depth: gyroscopes for the measurement of angular movement, where the basic laws are provided, and a thorough review of existing devices is presented; and particle production devices for the generation of micrometer-sized droplets, where the two most common techniques are compared, along with the challenges that remain open. Finally, some conclusions and perspectives for the future are presented and discussed.

The nanogap Pirani—a pressure sensor with superior linearity in an atmospheric pressure range

We have designed and fabricated a surface micromachined Pirani pressure sensor with an extremely narrow gap between its heater and heatsink (substrate) with superior output linearity in the atmospheric pressure range. The gap size of the device has been reduced to 50 nm by using a layer of PECVD amorphous silicon as a sacrificial layer and a xenon difluoride (XeF2) gas phase etching technique. Such a narrow gap pushes the transition from molecular to continuum heat conduction to pressures beyond 200 kPa. The higher transition pressure increases the measurement range and sensitivity of the gauge in atmospheric pressures. The gas phase etching of the sacrificial layer eliminates stiction problems related to a wet etching process. The active area of the sensor is only a 6 × 50 µm2 microbridge anchored to the substrate at both ends. An innovative fabrication technique was developed which resulted in a virtually flat microbridge with improved mechanical robustness. This process enabled us to have a very well-controlled gap between the microbridge and the substrate. The device was tested in a constant heater temperature mode with pressure ranges from 0.1 to 720 kPa. The heater power was only 3 mW at 101 kPa (atmospheric pressure), which increased to about 8 mW at 720 kPa. The output sensitivity and nonlinearity of the device were 0.55% per kPa at 101 kPa and ±13% of the output full scale, respectively.

Governing equation and fabrication techniques for ionic conductive polymer films

Dynamic analysis of sandwiched driving diaphragms, made of ionic conductive polymer (ICP), and an innovative fabrication technique to micromachine them are reported. The dynamics of ICP film (ICPF) is theoretically studied and described by governing equations via chemical and mathematical analysis. The purpose of deriving the governing equations is to explore the explicit relation of the induced lateral deflection of ICPF with respect to an applied electrical field. This is the first major issue of this report. The other major issue is ICPF fabrication technology. The device structure of the micropump unit, made of polydimethylsiloxane (PDMS), and the sandwiched ICPF are successfully integrated as a monolithic driving module by the proposed innovative fabrication technique. From the viewpoint of mass production, there are three challenging targets to be achieved. First, a novel method to fabricate ICPF actuators is developed to overcome the conventional defect: insufficient adhesion of coated electrodes upon ICPF. Second, the ICPF has to be restrained considerably to keep it straight and flat as it is fabricated, even though its thickness is far less than its length. Last, the ICPF has to operate in an aqueous environment. The proposed fabrication technique fully takes this into consideration.

Fabrication and analysis of ionic conductive polymer films for micro drug delivery systems

Dynamic analysis of well-bonding sandwich-alike driving diaphragms, made of ionic conductive polymer (ICP), and an innovative fabrication technique to micro-machine them are reported. Firstly, the dynamics of ICP film (ICPF), serving as an actuator, is theoretically studied and described in governing equation via chemical and mathematical analysis. The purpose is to explore the explicit expression in differential equation upon the direct connection of the induced lateral deflection of ICPF with respect to exerted electrical field. This is the first major issue of this paper: output/input relation. The other major issue is its fabrication technology. That is, the structure layers, made of polydimethylsiloxane (PDMS), and the sandwiched ICPF are successfully integrated as a monolithic driving actuator by an innovative fabrication technique. As for technology, there are three challenging targets to be well achieved. First of all, the novel method to fabricate ICPF actuators is well developed to overcome conventionally insufficient adhesion of added-externally electrodes upon ICPF. Secondly, the ICPF has to be kept right straight and flat as it is fabricated, even though its thickness is far less than its length. Lastly, the ICPF has to function in aqueous environment that is fully taken into consideration at the stage of fabrication.

Novel Intra-Tissue Perfusion System for Culturing Thick Liver Tissue

Innovative scaffold fabrication, angiogenesis promotion, and dynamic tissue culture techniques have been utilized to improve delivery of media into the core of large tissue constructs in tissue engineering. We have developed here an intra-tissue perfusion (ITP) system, which incorporates an array of seven micron-sized needles as a delivery conduit, to improve mass transfer into the core of thick liver tissues slices (>>300 microm mass transport limit). The ITP system improves the uniformity and distribution of media throughout the tissue, resulting in improved cell viability over the static-cultured controls. The ITP-cultured thick liver slices also exhibit improved phase I and phase II metabolic functions and albumin and urea synthetic functions after 3-day culture, which is the minimal period required by the U.S. Food and Drug Administration (FDA) for studying drug-drug interaction. This ITP system can also be used for culturing other thick tissue constructs of larger dimensions for various in vitro and in vivo applications, including bridging integration of the in vitro cultured constructs into living host tissues.

Dynamic simulation and novel fabrication technique on ICPF-based micro-actuators for flexible micro dosing systems

Dynamic analysis of sandwiched driving diaphragms, made of ionic conductive polymer (ICP), and an innovative fabrication technique to micro-machine them are reported. Firstly, the dynamics of ICP film (ICPF) is theoretically studied and described by governing equations via chemical and mathematical analysis. The purpose to derive the governing equations is to explore the explicit relation of the induced lateral deflection of ICPF with respect to applied electrical field. This is the first major issue of this report. The other major issue is ICPF fabrication technology. The device structure of the micro pump unit, made of polydimethylsiloxane, and the sandwiched ICPF are successfully integrated as a monolithic driving module by the proposed innovative fabrication technique. From the viewpoint of mass production, there are three challenging targets to be achieved. First of all, the novel method to fabricate ICPF actuators is developed to overcome the conventional defect: insufficient adhesion of coated electrodes upon ICPF. Secondly, the ICPF has to be retained considerably right straight and flat as it is fabricated, even though its thickness is far less than its length. Lastly, the ICPF has to operate in aqueous environment. This has been fully taken into consideration by the proposed fabrication technique.