Proposed Fabrication Procedure Research Articles

Ultra-Strong, Ultra-Tough, Transparent, and Sustainable Nanocomposite Films for Plastic Substitute

Summary Plastics play a critical role in daily life but possess a considerably increasing negative impact on the environment and human health. Fabrication of biodegradable and eco-friendly alternatives with competitive properties for plastic substitute is urgently needed. Here, inspired by the hierarchical structure of nacre, we firstly developed a high-performance nacre-inspired composite with high transmittance (83.4% at 550 nm) and high haze (88.8% at 550 nm) via an aerosol-assisted biosynthesis process combined with the hot-press technique. The nacre-inspired composite film combines higher strength (482 MPa) and toughness (17.71 MJ m−3) than most other nacre-inspired films, and can be folded into various shapes without visible failure after unfolding. Moreover, compared with most commercial plastic films, it exhibits a lower thermal expansion coefficient (∼3 ppm K−1) and higher maximum service temperature besides better mechanical properties, which makes it a promising alternative to plastics in many technical fields.

One-step modification of nano-polyaniline/glucose oxidase on double-side printed flexible electrode for continuous glucose monitoring: Characterization, cytotoxicity evaluation and in vivo experiment

The single-step modification of the nanostructured polyaniline (PANI)/glucose oxidase (GOD) enzyme on double-sided, screen-printed, flexible electrodes doped with Prussian blue (PB), has been achieved and successfully applied in continuous glucose monitoring in vivo, and its biocompatibility has been evaluated systematically. The proposed fabrication procedure is simple, low cost, and suitable for large-scale production. PB doped with carbon ink catalyzes the reduction of hydrogen peroxide (H2O2) in low-voltage conditions, which could help eliminate interferences. And the PANI/GOD nanostructure makes the GOD enzyme more stable for long-term, in vivo monitoring. More importantly, a polyurethane (PU) layer is deposited on the electrode's surface as a diffusion limiting membrane that enhanced the linear range and biocompatibility. In tests in vitro, the proposed biosensor achieved a linear range of 0–12 mM and a good sensitivity of 16.66 μA·mM−1·cm−2(correlation coefficient R2 = 0.9962) with an excellent specificity to glucose. The biosensor exhibits long-term stability, with a maximum lifespan of 14 days when stored in phosphate buffer solution at 4 °C, and achieves a sensitivity of 120%. The biocompatibilities of the electrode materials have also been systematically evaluated in cytotoxicity and cell adhesion tests to ensure the safety of implantation. In experiments in vivo, the biosensor can successfully monitor the glucose level fluctuation of rats after 24 h following implantation. Overall, the biosensor fabricated with the double-side, screen-printing process, satisfies the glucose monitoring range in vivo and eliminates various types of interference, thus establishing a new, large-scale production procedure for flexible in vivo biosensors.

High-yield fabrication method for high-frequency graphene devices using titanium sacrificial layers

The authors present a fabrication process for the development of high-frequency (>30 GHz) on-wafer graphene devices with the use of titanium sacrificial layers. Graphene patterning requires chemical processes that have deleterious effects on graphene resulting in very low yield. The authors prevent delamination of the delicate graphene from the substrate during the fabrication steps by depositing a blanketing 30 nm titanium layer at the beginning of the process. Additionally, titanium is a low cost, hazardless, and well-established material in the semiconductor industry and, therefore, constitutes an attractive solution for graphene protection. With the proposed blanketing approach, the authors obtain more than 90% device yield, allowing the development of graphene-based reconfigurable, large-area, high-frequency topologies such as antenna arrays. Without the use of this titanium sacrificial layer, they show that the expected yield plummets. In addition, they validate the proposed fabrication procedure through on-wafer measurements in the 220–330 GHz range.

Design and Optimization Techniques of Over-Chip Bond-Wire Microtransformers With LTCC Core

This paper describes the realization of bond-wire micromagnetics by using standard bonding wires and a toroidal ferromagnetic low-temperature co-fired ceramic core with high resistivity. The proposed fabrication procedure is suitable for the development of magnetic components on the top of an integrated circuit with a small profile and a small size ( $\sim 33~\mu \text{H}$ ) and high effective turns ratio (~20). Applications include bootstrap circuits and micropower conversion for energy harvesting. Measurements demonstrate a maximum secondary Q-factor of 11.6 at 1.3 MHz, and a coupling coefficient of 0.65 with an effective turns ratio of 19, which are among the highest values reported for toroidal miniaturized magnetics. The achieved inductance density is $2~\mu \text{H}$ /mm2, along with an inductance per unit core volume of 15.6 $\mu \text{H}$ /mm3, and a dc inductance-to-resistance ratio of 2.23 $\mu \text{H}/\Omega $ . The presented technique allows to obtain over-chip magnetics trough a postprocessing of the core, and it is also suitable for high-density power supply in package and power supply on-chip. Finally, a series of optimization techniques for planar core magnetic devices in order to maximize the inductance per unit area is discussed and applied to the considered case.

Microfluidic packaging of high-density CMOS electrode array for lab-on-a-chip applications

Effective packaging and integration of microfluidic components with a small electronic chip, such as a complementary metal–oxide–semiconductor (CMOS) chip, is crucial for the ultimate realization of lab-on-a-chip (LOC) devices. Hence, the methods and materials used for the integration should provide good reproducibility, reliability, biocompatibility, and capability for mass production. This paper introduces a new concept that allows the miniaturization of microfluidic packaging and the integration of CMOS chips. The photosensitive polymer material used in this study serves not only as a photoresist to pattern diverse shapes of microfluidic structures at the wafer level, but also as an adhesive to bond the Indium-Tin-Oxide (ITO) coated glass chip to the CMOS die. The patterning process, using conventional photolithography, was demonstrated with a wide range of thicknesses from 10μm to 80μm, and reliable seamless bonding was achieved with a conventional flip-chip bonder. We also validated that the proposed packaging can be utilized in biological experiments by culturing live cells (MCF-7) for three days and by measuring the auto-fluorescence from the polymer material in the test-vehicles. In addition, the performance of the proposed packaging method was demonstrated by applying it to the microfluidic/CMOS hybrid chip for preliminary electrochemical testing (impedance measurement), and particle entrapment testing (dielectrophoresis experiment). The proposed fabrication procedure is expected to facilitate the wide adoption of CMOS technology in LOC applications.

Methods for Generating Highly Magnetically Responsive Lanthanide-Chelating Phospholipid Polymolecular Assemblies.

Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and its lanthanide ion (Ln3+) chelating phospholipid conjugate, 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA), assemble into highly magnetically responsive polymolecular assemblies such as DMPC/DMPE-DTPA/Ln3+ (molar ratio 4:1:1) bicelles. Their geometry and magnetic alignability is enhanced by introducing cholesterol into the bilayer in DMPC/Cholesterol/DMPE-DTPA/Ln3+ (molar ratio 16:4:5:5). However, the reported fabrication procedures remain tedious and limit the generation of highly magnetically alignable species. Herein, a simplified procedure where freeze thawing cycles and extrusion are replaced by gentle heating and cooling cycles for the hydration of the dry lipid film was developed. Heating above the phase transition temperature Tm of the lipids composing the bilayer before cooling back below the Tm was essential to guarantee successful formation of the polymolecular assemblies composed of DMPC/DMPE-DTPA/Ln3+ (molar ratio 4:1:1). Planar polymolecular assemblies in the size range of hundreds of nanometers are achieved and deliver unprecedented gains in magnetic response. The proposed heating and cooling procedure further allowed to regenerate the highly magnetically alignable DMPC/Cholesterol/DMPE-DTPA/Ln3+ (molar ratio 16:4:5:5) species after storage for one month frozen at -18 °C. The simplicity and viability of the proposed fabrication procedure offers a new set of highly magnetically responsive lanthanide ion chelating phospholipid polymolecular assemblies as building blocks for the smart soft materials of tomorrow.

Epoxidized multi-walled carbon nanotube buckypapers: A scaffold for polymer nanocomposites with enhanced mechanical properties

High volume fraction carbon nanotubes (CNTs) composites were fabricated by using the buckypaper approach. CNTs were modified by an epoxidation treatment to achieve high degree of chemical bonding with the epoxy matrix. The fabricated buckypapers exhibited high porosity, allowing the epoxy resin to fully penetrate inside the structure of the film. The hybrid material was found to exhibit specific strength of the same order of magnitude as aluminium-based industrial sheets. The usage of micro-Raman spectroscopy to assess the stress transfer from the polymer to the individual or bundled CNTs upon loading revealed that the enhanced mechanical integrity of such materials is due to the friction and contact forces of a huge number (∼1023m−3) of inter-bundle junctions. The proposed fabrication procedure can be easily extended towards the preparation of laminated composites at the industrial scale.

Microwave use of gypsum dehydration feasibility study

In this paper, we present the base techniques of a new fabrication procedure to obtain β-semy-hidrated calcium sulphate, β-plaster. The plaster is an aerial binder obtained through the dehydration of gypsum (CaSO4×2H2O) and forming semy-hidrated calcium sulphate (CaSO4×0,5H2O) at temperatures ranging between 110–160 °C. All plaster fabrication procedures used to this day are uneconomic. To obtain a larger deviated power, the application of a more intense electrical field is necessary. The dissipated power can also be increased by increasing the frequency; this can be done easily by using microwaves. They are applied more and more in industrial heating techniques, using high-frequency generators of a high powers and high-power magnetrons. The advantage of the microwave generators which use high-power magnetrons is that they are simple and cheap. The proposed fabrication procedure employs microwave energy and is based on the dielectric propriety of gypsum. As such, it is possible that the gypsum is dehydrated through dialectical heating into a resonant cavity with the microwave power. Water could absorb microwaves and increase the temperature rapidly within a short time. The results show that it is possible to use gypsum as a natural dielectric material in creating plaster through heating in a microwave field. Semi-hydrate produced under these conditions has the following characteristics: the beginning of binding 18–25 min., the end 28–37 min., compression strength after 2 h 2–5 MPa, compression strength of dried products 6–11 MPa.DOI: http://dx.doi.org/10.5755/j01.ct.63.1.4518

Efficient Prestressed Concrete-Steel Composite Girder for Medium-Span Bridges. I: System Description and Design

A new prestressed concrete-steel composite (PCSC) girder system is developed to provide a viable alternative for steel and prestressed concrete I-girders in bridges. The PCSC girder is composed of a lightweight W-shaped steel section with shear studs on its top and bottom flanges to achieve composite action with the pretensioned concrete bottom flange and the cast-in-place concrete deck. The PCSC girder is lightweight, economical, durable, and easy to fabricate. The proposed fabrication procedure is similar to those of prestressed concrete girders and does not need specialized equipment, materials, and forms. A service design procedure is proposed using the age-adjusted elasticity modulus method to evaluate the time-dependent stresses and strains in the PCSC girder caused by creep and shrinkage effects of concrete and relaxation of strands. The strength design method is proposed for the design of PCSC girders at prestress release. A design procedure is proposed to assist engineers to accomplish economic design and production of PCSC girders, and design examples are presented to illustrate the design procedure.

Lab-on-Fiber Technology: Toward Multifunctional Optical Nanoprobes

We propose a reliable fabrication process enabling the integration of dielectric and metallic nanostructures on the tip of optical fibers, thus representing a further step in the "lab-on-fiber" technology roadmap. The proposed fabrication procedure involves conventional deposition and nanopatterning techniques, typically used for planar devices, but here adapted to directly operate on optical fiber tip. Following this approach, we demonstrate a first technological platform based on the integration onto the optical fiber tip of two-dimensional hybrid metallo-dielectric nanostructures supporting localized surface plasmon resonances. By means of experimental measurements and full-wave numerical simulations, we characterize these resonant phenomena and investigate the underlying physics. We show that resonances can be easily tuned by acting on the physical and geometrical parameters of the structure. Moreover, with a view toward possible applications, we present some preliminary results demonstrating how the proposed device can work effectively as an optical probe for label-free chemical and biological sensing as well as a microphone for acoustic wave detection.

Airborne ultrasonic vortex generation using flexible ferroelectrets

Cellular ferroelectrets exhibit interesting electromechanical- acoustical characteristics. Their recent appearance and remarkable properties open up new possibilities for the design and development of ultrasonic transducers. In particular, the feasibility of fabricating ultrasonic vortex generators using ferroelectret films is demonstrated in this work. To this end, a transducer prototype was built by gluing the material onto a tangential-helical surface (outer diameter: 40 mm, pitch: 3.45 mm). Experimental results agree well with the theoretical estimation of the pressure and phase of the acoustic field in the near field and far field, which corroborates the potential of ferroelectrets to customize special acoustic fields. Furthermore, the proposed fabrication procedure is inexpensive and represents a new alternative for exploring and analyzing the special characteristics of acoustical helical wavefronts.

TCAD study on gate-all-around cylindrical (GAAC) transistor for CMOS scaling to the end of the roadmap

In this paper, we report TCAD study on gate-all-around cylindrical (GAAC) transistor for sub-10-nm scaling. The GAAC transistor device physics, TCAD simulation, and proposed fabrication procedure have been discussed. Among all other novel fin field effect transistor (FinFET) devices, the gate-all-around cylindrical device can be particularly used for reducing the problems of conventional multi-gate FinFET, improving device performance, and scaling-down capabilities. With gate-all-around cylindrical architecture, the transistor is controlled essentially by infinite number of gates surrounding the entire cylinder-shaped channel. Electrical integrity within the channel is improved by reducing the leakage current due to the non-symmetrical field accumulation such as the corner effect. Our proposed fabrication procedure for making devices having the gate-all-around cylindrical (GAAC) device architecture is also discussed.

Measurement of Dissolved Oxygen and Its Diffusivity in Aerobic Granules Using a Lithographically-Fabricated Microelectrode Array

A novel gold microelectrode array (MEA) was manufactured with microfabrication techniques and applied on the measurement of dissolved oxygen profile in an aerobic granule. The MEA contained five gold microelectrodes, which had a good linear response to dissolved oxygen and typically had a lifetime of more than 10 days. Dissolved oxygen microprofiles near the surface of an aerobic granule were monitored with this MEA. Based on the measurements, an oxygen effective diffusivity in the upper 100 microm layer of the aerobic granule was estimated to be 1.19 x 10(-9) m2/s. The experimental results demonstrate that the MEA was able to measure the DO levels in aerobic granules accurately and precisely and that the MEA could be used to determine constituents, profiles, and functions in situ in small spaces. Moreover, since the device shape and microelectrode arrangement were all defined by photolithography, the proposed fabrication procedure was flexible and appropriate for fabrication of various types of MEAs.