Micro and Nano Engineering最新文献

Energy harvesting and conservation are essential for all kinds of power sources, particularly renewable energy sources, given their global distribution. Usually, batteries are employed to mitigate the imbalance between abundant renewable energy generation and inefficient energy transmission. However, batteries suffer from a drawback in terms of low power density. In recent years, supercapacitor devices have gained significant traction in energy systems due to their enormous power density, competing favorably with conventional energy storage solutions. This research paper comprehensively overviews various supercapacitor modalities, encompassing electrode materials, electrolytes, structures, and working principles. Furthermore, it explores the diverse applications of supercapacitors in the consumption of renewable energy, showcasing their potential in various domains, thereby reflecting the thriving prospects of these devices in modern society. Finally, the paper addresses the challenge of energy management in conjunction with supercapacitors.

As proven early on in the pandemic, SARS-CoV-2 is mainly transmitted by aerosols. This urged us to develop a silicon impactor that collects the virus particles directly from breath. Performing PCR on these breath samples proved equally sensitive as nasopharyngeal swabs during the first week of an infection [Stakenborg et al., 2022], yet it remained a mostly manual process and PCR turn-around-time was still long. To overcome these drawbacks, we developed a fast and sensitive, fully integrated point-of-need breath test, comprising a novel breath sampler device and PCR instrument. The breath sampler combines virus collection and in-situ RNA amplification. The PCR instrument performs very fast amplification of the released viral RNA. Sample-to-result time was reduced to <20 min with an equal performance as the original manual procedure.

The wafer-scale fabrication of deep channel microfluidics for lab-on-a-chip applications by reactive ion etching and wafer bonding is reported. The microfluidic channels are etched in B-stage bisbenzocyclobutene (BCB) and Cytop with the latter used as a bonding agent. The channels are hermetically sealed between Borofloat glass and Si wafers by wafer bonding. Fluidic coupling is achieved in the plane of the channels via inlets and outlets that are revealed on the end facets of chips after dicing. Process techniques and details are reported for uniform coating and curing of BCB and Cytop, defining the channels with high accuracy using photolithography, dry etching the polymers using a hard mask, and sealing the channels by wafer bonding. Fluidic measurements are carried out at various flow rates and compared with modeling. The low Reynold's numbers of the channels ensure laminar flow conditions. Deep fluidic channels are less difficult to align to fluidic interfaces, they support higher flow rates and are less susceptible to clogging. In-plane fluidic coupling precludes the need to etch holes through the substrate. Our wafer-scale process was applied to 4 in. diameter wafers yielding 195 precision-aligned and hermetically sealed microfluidic chips, but is readily scalable to larger diameter wafers for volume production.

Au-based micro-electro-mechanical-system (Au-MEMS) capacitance accelerometers show high sensitivity by suppressing the mechanical noise because of the high mass density of gold (ρ = 19.3 g/cm³). On the other hand, their long-term reliability suffers from drift phenomena induced by the impurities incorporated in the key component during their fabrication process, such as the gold electroplating step. Herein, impurities in electroplated Au-based components for MEMS capacitive accelerometers are evaluated by thermal desorption spectrometry (TDS) measurements. The TDS measurement reveals that dominant desorption gases from the Au-based component are molecular hydrogen (H₂) and water (H₂O). These desorption gases are derived from impurities in the electroplated Au-based component, and the amount of these gases is significantly suppressed by a thermal treatment step. In conclusion, this study demonstrates that the electroplated Au-based component contains impurities originated from the fabrication process, and these impurities could be removed by a thermal treatment step.

Low temperature detectors (LTDs) used for decay energy spectrometry (DES) can provide accurate and reliable decay data thanks to their high-energy resolution and a near 100% detection efficiency for the radiations of interest. However, it is essential to consider the source quality to mitigate spectral distortion due to the self-absorption of particle energy in the source deposited.

This work aimed to produce a replaceable 4π 3-layer gold absorber for DES in reusable metallic magnetic calorimeters, a class of LTDs. We present a novel 3-layer microfabrication process for a 1 mm diameter absorber with a total gold thickness ranging from 20 μm to 120 μm depending on the measured radionuclide (⁵⁵Fe or ²⁴¹Am). The absorber integrates a gold nanofoam in which the radionuclide is deposited by nanodrop deposition of a few tenths of μL of a radioactive solution. We fabricated a high quality gold nanofoam layer with controllable porosity through a dealloying process using wet etching and integrating it on a thick electrodeposited gold layer. The fine study of the nanofoam microfabrication is performed using high-resolution scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX).

Electronic waste has become a pressing issue, necessitating sustainable solutions for the disposal of electronic devices. While the development of environmentally degradable electronics has gained attention, the fabrication of stable and performant sensors from biodegradable materials remains challenging. We present printed degradable resistance temperature detectors (RTDs) based on the photonic sintering of a zinc microparticles ink on a cellulosic substrate. Efficient sintering is attained via a two-step process involving electrochemical oxide removal and pulsed light exposure using a xenon lamp. By optimizing the pulse energy and pulse count, we obtain highly linear zinc-based RTDs with a high temperature coefficient of resistance (TCR). The printed zinc reaches a TCR value of 3160 ppm/K, which represents about 80% of the value of the bulk material. The dynamic response of the sensors in a range from −20 to 40 °C closely matches the temperature signal recorded by a commercial sensor. The encapsulation of the screen-printed sensors on paper substrate with a biodegradable beeswax coating ensures protection against the interference of moisture. These printed RTDs, fully made of degradable materials, pave the way to the cost-effective manufacturing of eco-friendly yet performant sensors for environmental monitoring.

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.