Micromachines最新文献

Microneedle (MN) technologies have emerged as a groundbreaking platform for transdermal and intradermal drug delivery, offering a minimally invasive alternative to oral and parenteral routes. Unlike passive transdermal systems, MNs allow the permeation of hydrophilic macromolecules, such as peptides, proteins, and vaccines, by penetrating the stratum corneum barrier without causing pain or tissue damage, unlike hypodermic needles. Recent advances in materials science, microfabrication, and biomedical engineering have enabled the development of various MN types, including solid, coated, dissolving, hollow, hydrogel-forming, and hybrid designs. Each type has unique mechanisms, fabrication techniques, and pharmacokinetic profiles, providing customized solutions for a range of therapeutic applications. The integration of 3D printing technologies and stimulus-responsive polymers into MN systems has enabled patches that combine drug delivery with real-time physiological sensing. Over the years, MN applications have grown beyond vaccines to include the delivery of insulin, anticancer agents, contraceptives, and various cosmeceutical ingredients, highlighting the versatility of this platform. Despite this progress, broader clinical and commercial adoption is still limited by issues such as scalable and reliable manufacturing, patient acceptance, and meeting regulatory expectations. Overcoming these barriers will require coordinated efforts across engineering, clinical research, and regulatory science. This review thoroughly summarizes MN technologies, beginning with their classification and drug-delivery mechanisms, and then explores innovations, therapeutic uses, and translational challenges. It concludes with a critical analysis of clinical case studies and a future outlook for global healthcare. By comparing technological progress with regulatory and commercial hurdles, this article highlights the opportunities and limitations of MN systems as a next-generation drug-delivery platform.

Large-area metasurfaces were fabricated via a tunable pyramidal interference lithography (PIL) technique, which uses custom-built 2-faced, 3-faced, and 4-faced pyramidal prisms to create metasurfaces with customizable nano- and micro-scale surface feature periodicities. The 2-faced prism produced linear surface relief diffraction gratings, while the 3-faced prism produced metasurfaces with triangular lattices and the 4-faced prism produced metasurfaces with square lattices, all on azobenzene thin films. A double inline prism set-up enabled control over the metasurface feature periodicity, allowing systematic increase in the pattern size. Additional tunability was achieved by placing a prism inline with a lens, allowing precise control over the metasurface feature periodicity. A theoretical model was derived and successfully matched to the experimental results. The resulting metasurfaces were coated with gold and exhibited distinct surface plasmon resonance (SPR) and surface plasmon resonance imaging (SPRi) responses, confirming their functionality. Overall, this work establishes PIL as a cost-effective and highly adaptable metasurface fabrication method for producing customizable periodic metasurfaces for photonic, plasmonic, and sensing applications.

Microfluidic paper-based analytical devices (µPADs) convert ordinary cellulose into an active analytical platform where capillary gradients shape transport, surface chemistry guides recognition, and embedded electrodes or optical probes translate biochemical events into readable signals. Progress in fabrication-from wax and stencil barriers to laser-defined grooves, inkjet-printed conductive lattices, and 3D-structured multilayers-has expanded reaction capacity while preserving portability. Detection strategies span colorimetric fields that respond within porous fibers, fluorescence and ratiometric architectures tuned for low abundance biomarkers, and electrochemical interfaces resilient to turbidity, salinity, and biological noise. Applications now include diagnosing human body fluids, checking food safety, monitoring the environment, and testing for pesticides and illegal drugs, often in places with limited resources. Researchers are now using learning algorithms to read minute gradients or currents imperceptible to the human eye, effectively enhancing and assisting the measurement process. This perspective article focuses on the newest advancements in the design, fabrication, material selection, testing methods, and applications of µPADs, and it explains how they work, where they can be used, and what their future might hold.

In the original publication [...].

In this paper, a coupled negative bias temperature instability (NBTI)/hot carrier degradation (HCD) failure model is proposed on the 2-D voltage plane for aging simulation of SRAM circuits. According to the physical mechanism of failure, based on the reaction-diffusion and hot carrier energy-driven theory, revised degradation models of threshold voltage shift (∆Vth) for the NBTI and HCD are established, respectively, with explicit expressions for gate voltage (V_G)/drain voltage (V_D). An NBTI/HCD coupling model is built on the 2-D {V_G, V_D} voltage plane with a weighting factor in the form of V_G and V_D power law. The model also takes into account the AC effect and long-term saturation behavior. The predicted ∆Vth under various stress conditions shows an average relative error of 11.6% with experimental data across the entire bias space. SRAM circuit simulation shows that the read static noise margin (RSNM) and write static noise margin (WSNM) have a maximum absolute error of 4.2% and 3.1%, respectively. This research provides a valuable reference for the reliability simulation of nanoscale integrated circuits.

Dye-sensitized solar cells (DSSCs) have attracted significant attention as next-generation photovoltaic devices due to their low cost, simple fabrication process, use of earth-abundant materials, and potential for colour tunability and transparency. p-n tandem DSSCs have garnered particular interest owing to their higher open-circuit voltage compared to single-junction DSSCs. However, the performance of such tandem devices remains limited by relatively low open-circuit voltage and short-circuit current density, primarily due to the scarcity of suitable p-type sensitizers. To address this challenge, we report a novel p-n tandem solar cell integrating a dye-sensitized TiO₂ photoanode with a perovskite-sensitized NiO photocathode, achieving a record power conversion efficiency of 4.02%. By optimizing the thickness of the TiO₂ layer, a maximum open-circuit voltage of 1060 mV and a peak short-circuit current density of 6.11 mA cm^-2 were simultaneously attained.

We report a notable enhancement in the performance of small-molecule-based organic photovoltaics (OPVs) through the use of a ternary blend comprising a small-molecule donor (DTS(FBTTh₂)₂), a polymer donor (PBDTTT-EFT), and a fullerene acceptor (PC₇₁BM). By optimizing the composition of this ternary active layer, we achieved a significant increase in power conversion efficiency from 7.99% to 9.08%. This improvement is attributed to the broader light absorption spectrum and enhanced charge transport pathways provided by the polymeric donor. PBDTTT-EFT optimizes the nanomorphology and ordering of the bulk heterojunction films and forms a cascade energy level that enhances charge carrier mobility. Our results demonstrate that semiconducting polymer donors can effectively control light absorption, charge transport, and exciton dissociation by optimizing morphology and crystallinity. This approach offers new possibilities for advancing the performance of various optoelectronic devices through strategic use of different semiconducting polymer donors.

A vertical Ni/β-Ga₂O₃ Schottky barrier diode was fabricated on an unintentionally doped bulk (-201)-oriented β-Ga₂O₃ single crystal and investigated with a focus on the underlying photoresponse mechanisms. The device exhibits well-defined rectifying behavior, characterized by a Schottky barrier height of 1.63 eV, an ideality factor of 1.39, and a high rectification ratio of ~9.7 × 10⁶ arb. un. at an applied bias of ±2 V. The structures demonstrate pronounced sensitivity to deep-ultraviolet radiation (λ ≤ 280 nm), with maximum responsivity observed at 255 nm, consistent with the wide bandgap of β-Ga₂O₃. Under 254 nm illumination at a power density of 620 μW/cm², the device operates in a self-powered mode, generating an open-circuit voltage of 50 mV and a short-circuit current of 47 pA, confirming efficient separation of photogenerated carriers by the built-in electric field of the Schottky junction. The responsivity and detectivity of the structures increase from 0.18 to 3.87 A/W and from 9.8 × 10⁸ to 4.3 × 10¹¹ Hz^0.5cmW^-1, respectively, as the reverse bias rises from 0 to -45 V. The detectors exhibit high-speed performance, with rise and decay times not exceeding 29 ms and 59 ms, respectively, at an applied voltage of 10 V. The studied structures demonstrate internal gain, with the external quantum efficiency reaching 1.8 × 10³%.

On-orbit cutting is a critical process for the on-orbit manufacturing of carbon fiber reinforced polyetheretherketone composites (CF/PEEK) truss structures, with pulsed laser cutting serving as one of the feasible methods. Achieving high-quality cutting of CF/PEEK remains a major challenge for on-orbit manufacturing. Therefore, the cutting process of CF/PEEK prepreg tape was studied by an ultraviolet (UV) nanosecond laser. A three-factor, five-level orthogonal experiment was carried out to analyze the influence of laser repetition rate (LRR), laser cutting speed (LCS), and laser scanning times (LCTs) on cutting quality. The ablation mechanism dominated by the photothermal effect between the UV nanosecond laser and CF/PEEK was analyzed, and the by-products in the cutting process were explored. Finally, the optimal cutting quality (the width of slit (W_s) = 41.69 ± 3.54 μm, the heat-affected zone (HAZ) = 87.27 ± 7.30 μm) was obtained under the process conditions of LRR 50 kHz-LCS 50 mm/s-LCT 16 times. The findings show that the W_S and HAZ increase with the increase in LRR and LCT and the decrease in LCS, and the carbon fiber decomposes and escapes due to the photothermal effect.

Nanoaperture optical tweezers (NOTs) were used to analyze conalbumin in various forms. By analyzing the power spectrum of the NOT-transmitted laser signal, differences between iron and iron-free conalbumin were observed; the corner frequency extrapolated to zero-laser power was significantly larger in magnitude for conalbumin with iron, which was interpreted as coming from the enhanced electrostatic interactions close to the surface of the nanoaperture. Conalbumin in a diluted, but otherwise unprocessed, egg white sample showed the same behavior as purified iron-free conalbumin. Dynamic two-state transitions in the NOT signal were observed for iron-free conalbumin and conalbumin in egg white samples. We used this to determine the dominant state as a function of temperature, with one state showing a maximum occupancy around 30.4 °C. Deconvolution of the probability distribution function was used to find the energy landscape associated with this two-state transition. This work shows the potential of NOTs to see variations with metal ion binding, including conformational dynamics related to the binding at timescales not accessible to other methods.