Micro and Nano Engineering最新文献

In this study, we present the performance of an extreme ultraviolet interference lithography (EUV-IL) setup that was reconstructed at Taiwan Light Source 21B2 EUV beamline in the National Synchrotron Radiation Research Center (NSRRC), Taiwan. An easy-to-perform fabrication method to produce a high-quality transmission grating mask and a simple design of experimental setup for EUV-IL were developed. The current EUV-IL setup is capable of fabricating line/space patterns down to 25 nm half-pitch in hydrogen silsesquioxane (HSQ) resist. Preliminary exposure results revealed that optimized slit width and exposure time significantly improved line/space pattern quality. The current EUV-IL tool at NSRRC can be used for nano-patterning and resist screening to advance the next generation of semiconductor devices.

Hydrogel based carriers have been predominantly investigated to combat the prominent challenges faced by oral biomacromolecule delivery. Several micromolding, microfluidic and photolithographic techniques have been described for the fabrication of non-spherical hydrogel based microcarriers. However, these techniques are unsuitable for loading biomacromolecules as integral part of the fabrication process due to the use of high temperatures, solvents and multiple processing steps. Here, we introduce UV-assisted punching as a novel two-step fabrication technique for the development of biocompatible microgel shapes for oral drug administration. Poly-ethylene glycol (PEG) microgel shapes with lateral dimensions of 25–100 μm and a height of 25 μm were fabricated on a flexible poly vinyl alcohol (PVA) substrate with a robust cycloolefin polymer (COP) stamp. The proposed process uses UV-initiated crosslinking of aqueous solutions at ambient temperatures, thereby providing a highly attractive method for the fabrication of biomacromolecule loaded hydrogel based carriers. For the proof-of-concept, the microgel shapes were loaded with the fluorescently labelled model biomacromolecule bovine serum albumin without any additional steps. The successful loading is demonstrated by fluorescence microscopy. In vitro studies are performed to quantify the macromolecular content and the release profile associated with the fabricated microgel shapes.

The synthesis of MoS₂ with chemical vapor deposition (CVD) using sodium molybdate (Na₂MoO₄) as the Mo precursor produces a big number of large flakes (∼100-300 μm) compared to other CVD methods that use different precursors. In this work, humidity sensors based on MoS₂ are developed, whereby MoS₂ is grown using this Mo precursor in an aqueous solution form. The final devices exhibit a response-switching during operation under high (>50%) relative humidity conditions, due to the presence of Na₂MoO₄ residues on their surface. By decreasing the concentration of the aqueous Mo precursor during the CVD process we partially diminish the switching effect, as the Na₂MoO₄ residue is reduced To completely overcome this issue, we present a post-fabrication surface treatment using hydrochloric acid that removes the Na₂MoO₄ residue from the devices' surface. Rinsing the devices with an HCl solution results in the elimination of the response-switching effect and the sensors demonstrate a constant positive response from the initial operation steps.

Wastewater containing synthetic dyes has caused a significant risk to the environment and human health. Among the various methods to treat wastewater, photocatalysis recommends itself as a particularly efficient tool for the removal of dyes from industrial effluents. In this work, Au@Cu₂O core@shell nanocrystals with controllable shell thicknesses from 38.1 ± 2.8 (Au@Cu₂O-2), 48.1 ± 3.7 (Au@Cu₂O-3) to 59.1 ± 4.1 nm (Au@Cu₂O-4) have been prepared and immobilized on polyethylene terephthalate (PET) fabrics for applications in photocatalytic degradation of methylene orange (MO). The influence of the shell thickness of Au@Cu₂O on the photocatalytic performance of the functionalized PET fabrics has been examined. Among all the samples tested, immobilization of Au@Cu₂O-3 rendered PET fabrics the largest photocatalytic activity for MO degradation, achieving an apparent rate constant of MO degradation of 7.43 × 10⁻³ min⁻¹. A plausible mechanism accounting for the degradation process of MO over the functionalized PET has been proposed based on the results of scavenger experiments. This work has provided a delicate yet practical functional textile paradigm by combining the photocatalytic capability of Au@Cu₂O and the adaptable feature of PET fabrics. The findings from this study can deliver a viable idea for the design of versatile textiles with competent photocatalytic capacity for environmental purifications and energy conversion.

This work describes the integration of a Resistance Thermal Detector (RTD) microcalorimeter integrated into a 324 nL microfluidic channel. The sensor is fabricated in a clean room using photolithography and evaporation techniques, and it has a platinum serpentine with 60 windings. The RTDs undergo testing in the 30 to 45 °C temperature range, exhibiting great linearity and a sensitivity of 8.42 Ω/°C. Additionally, to perform the thermic measurement, we also provide a circuit architecture that ensures stability against external thermal fluctuations and the self-heating Joule effect. We showed that this measurement method allow us to achieve a precision of ±6.7·10⁻³ °C, compared to ±0.178 °C total fluctuations found by using the traditional 2-wire method.

High strength Ni matrix TiO₂ composites are prepared by co-electrodeposition with an electrolyte composed of Ni Watts bath, surfactants, CO₂ in the supercritical fluid state and various sizes of TiO₂ particles. The surfactants and supercritical CO₂ (SC-CO₂) are used to emulsify the aqueous Ni Watts bath to promote the incorporation of TiO₂ particles into the Ni matrix. TiO₂ particles with three different average sizes are used in the co-electrodeposition to evaluate the effect on properties of the Ni-TiO₂ composites. The grain sizes of the Ni matrix in the composites are compared from the X-ray diffraction results and the Scherrer eq. A refined average grain size in the Ni matrix is observed when using TiO₂ particles with a larger size. The TiO₂ is evaluated by energy-dispersive X-ray spectroscopy (EDX), and the TiO₂ distribution is quantified by the coefficient of variation (cov) of the local density of Ti from the EDX result. The TiO₂ content attained 4.5 wt% with the lowest cov value (which suggests the most uniform distribution) in the composite when the smallest (21 nm) TiO₂ particles are used. The TiO₂ content achieves 22.3 wt% with the highest cov value (which suggests the least uniform distribution) when the largest (5 μm) TiO₂ particles are used. Microhardness of the Ni-TiO₂ composites is found to be highly depended on the cov value. Hence, the Ni-TiO₂ composite prepared with the smallest TiO₂ particles shows the highest microhardness at 1274 HV.

The optical properties and geometry of EUV mask absorbers play an essential role in determining the imaging performance of a mask in EUV lithography. Imaging metrics, including Normalized Image Log Slope (NILS), Telecentricity Error (TCE), and Best Focus Variation (BFV) through pitch deteriorate because of Mask 3-Dimensional (M3D) effects in EUV lithography, which limits the production efficiency. Alternative absorbers, including alloys of Ru and Ta, are anticipated to reduce some of the M3D effects; however, patterning these materials is challenging due to their low etch rates and poor etch selectivity against the Ru mask capping layer. Therefore, we propose a Ru/Ta bilayer approach to EUV mask absorbers and investigate it from a patterning and imaging standpoint. The top Ru layer thickness is calculated using the thin film interference phenomena, and we determine the bottom Ta layer that can produce improved NILS by utilizing the total absorber thickness optimization methodology. We demonstrate the patterning of the Ru/Ta bilayer using a two-step etch; the top Ru layer is patterned with Cl₂-O₂ Reactive Ion Etch (RIE), and the bottom Ta layer with Cl₂-N₂ RIE. The geometry and morphology of the patterned bilayer stack are investigated using TEM (Transmission Electron Microscopy), and interdiffusion at the interface of Ru and Ta is studied using EDS-STEM (Energy Dispersive X-ray Spectroscopy-Scanning Transmission Electron Microscopy). The non-ideal traits of the Ru/Ta bilayer stack, determined by experimental characterization techniques, are used to simulate the imaging performance and then compared against an ideal Ru/Ta bilayer stack, along with the reference Ta-based absorber. Even when non-idealities are considered, the simulation findings demonstrate that the Ru/Ta bilayer absorber exhibits improved NILS and reduced BFV compared to the Ta-based absorber. The outcomes encourage further research into the possibilities of multilayer absorbers, to tailor their optical characteristics by varying the thickness of individual layers.

Fine tuning of the material properties requires many trials and errors during the synthesis. The metal nanoparticles undergo several stages of reduction, clustering, coalescence and growth upon their formation. Resulting properties of the colloidal solution thus depend on the concentrations of the reagents, external temperature, synthesis protocol and qualification of the researcher determines the reproducibility and quality. Automatized flow systems overcome the difficulties inherent for the conventional batch approaches. Microfluidic systems represent a good alternative for the high throughput data collection. The recent advances in 3D-printing made complex topologies in microfluidic devices cheaper and easily customizable. However, channels of the cured photopolymer resin attract metal ions upon synthesis and create crystallization centers. In our work we present 3D-printed system for the noble metal nanoparticle synthesis in slugs. Alternating flows of oil and aqueous reaction mixtures prevent metal deposition on the channel walls. Elongated droplets are convenient for optical and X-ray diagnostics using conventional methods. We demonstrate the work of the system using Ag nanoparticles synthesis for machine-learning assisted tuning of the plasmon resonance frequency.

Hybrid nanoplasmonics is one of the most promising branch of nanophotonics which aims, in particular, to control the energy transfer between donor and acceptor nano-emitters via surface plasmons. Recently, an approach of nano-emitters positioning was introduced. It is based on two-photon polymerization of a photosensitive material which contains quantum dots as nano-emitters. This technique allowed for the integration of green quantum dots on plasmonic silver nanowires. In this article, we report on the use of this approach for integrating both green and red quantum dots on silver nanowires. The coupling between nano-emitters and propagating surface plasmons that are supported by the silver nanowires is reported and observed through their scattering at the nanowire ends. For both colors, a parametric study of the distance between the quantum dots and the nanowire extremity shows that precise control of the position of the launching sites enables control of light intensity at the wire end, through surface plasmon propagation length. More interestingly, by integrating two kinds of quantum dots on the same nanowire, we realized an efficient donor-acceptor hybrid nano-system, where green surface plasmons polaritons (from donors) are transformed into red plasmons (from acceptors) at controlled sites of the plasmonic guides, as a result of a frequency conversion of the plasmons polaritons.