Search Results (358)

Wearable pressure sensors have emerged as vital tools in personalized monitoring, promising transformative advances in patient care and diagnostics. Nevertheless, conventional devices frequently suffer from limited sensitivity, inadequate flexibility, and concerns regarding biocompatibility. Herein, we introduce silk fibroin, a naturally occurring protein extracted from silkworm cocoons, as a promising material platform for next-generation wearable sensors. Owing to its remarkable biocompatibility, mechanical robustness, and structural tunability, silk fibroin serves as an ideal substrate for constructing capacitive pressure sensors tailored to medical applications. We engineered silk-derived capacitive architecture and evaluated its performance in real-time human motion and physiological signal detection. The resulting sensor exhibits a high sensitivity of 18.68 kPa⁻¹ over a broad operational range of 0 to 2.4 kPa, enabling accurate tracking of subtle pressures associated with pulse, respiration, and joint articulation. Under extreme loading conditions, our silk fibroin sensor demonstrated superior stability and accuracy compared to a commercial resistive counterpart (FlexiForce™ A401). These findings establish silk fibroin as a versatile, practical candidate for wearable pressure sensing and pave the way for advanced biocompatible devices in healthcare monitoring. Full article

A simple and inexpensive thermal oxidation process is used to grow β-Ga₂O₃ oxide (β-Ga₂O₃) thin films/nanorods on a c-plane (0001) sapphire substrate using Ag/Au catalysts. The effect of these catalysts on the growth mechanism of Ga₂O₃ was studied by different characterization techniques, including X-ray diffraction analysis (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray analysis (EDX). The XRD results of the grown Ga₂O₃ on a sapphire substrate show three sharp diffraction peaks located at 19.31°, 38.70° and 59.38° corresponding to the $\left(\overline{2}01\right), \left(\overline{4}02\right)$ and $\left(\overline{6}03\right)$ planes of β-Ga₂O₃. Field Emission Scanning Electron Microscope (FESEM) analysis showed the formation of longer and denser Ga₂O₃ nanowires at higher temperatures, especially in the presence of silver nanoparticles as catalysts. Full article

Silver nanowire (AgNW)-based transparent conductive films are essential for flexible electronics due to their superior optoelectronic properties and mechanical flexibility. This review examines the characteristics and fabrication methods of AgNW thin films in detail. Among various fabrication techniques, the AgNW thin film produced by silk-screen printing exhibits the highest quality factor of 568.47, achieving 95.3% visible light transmittance of 95.3% and 13.6 Ω/sq sheet resistance. Ensuring the stability of AgNW films requires the deposition of protective layers through physical or chemical approaches. This review also systematically evaluates the different methods for preparing these protective layers, including their respective advantages and limitations. Furthermore, the review proposes strategies to enhance the conductivity, transparency, and flexibility of AgNW films. Finally, it discusses potential future applications and challenges, offering valuable insights for the development of next-generation flexible transparent electrodes. Full article

In this article, femtosecond laser scanning was used to create heterojunctions between silver nanowire (Ag NW) and graphene oxide (GO), resulting in a mechanical and electrical interconnection. Surface plasmon resonances (SPRs) were generated on the nanowire surface by using femtosecond laser irradiation, producing a periodically excited electric field along the Ag NWs. This electric field then interfered with the femtosecond laser field, creating strong localized heating effects, which melted the Ag NW and GO, leading to mechanical bonding between the two. The formation of these heterostructures was attributed to the transfer of plasmon energy from the Ag NW to the adjacent GO surface. Since the connection efficiency of the nanowires is closely related to the specific location and the polarization direction of the laser, FDTD simulations were conducted to model the electric field distribution on the surface of Ag NW and GO structures under different laser polarization directions, varying the lengths and diameters of the nanowires. Finally, the resistance changes of the printed Ag NW paths on the GO thin film after femtosecond laser irradiation were investigated. It was found that laser bonding could reduce the resistance of the Ag NW-GO heterostructures by two orders of magnitude, further confirming the formation of the junctions. Full article

Background/Objectives: Airborne viral diseases pose a health risk, due to which there is a growing interest in developing filter materials capable of capturing fine particles containing virions from the air and that also have a virucidal effect. Nanofiber membranes made of poly(vinylidene fluoride) dissolved in N,N-dimethylacetamide and functionalized with copper, silver, and zinc nanoclusters were fabricated via electrospinning. This study aims to evaluate and compare the virucidal effects of nanofibers functionalized with metal nanoclusters against the human influenza A virus A/WSN/1933 (H1N1) and SARS-CoV-2. Methods: A comprehensive characterization of materials, including X-ray diffraction, scanning electron microscopy, microwave plasma atomic emission spectroscopy, thermogravimetric analysis, contact angle measurements, nitrogen sorption analysis, mercury intrusion porosimetry, filtration efficiency, and virucidal tests, was used to understand the interdependence of the materials’ physical characteristics and biological effects, as well as to determine their suitability for application as antiviral materials in air filtration systems. Results: All the filter materials tested demonstrated very high particle filtration efficiency (≥98.0%). The material embedded with copper nanoclusters showed strong virucidal efficacy against the SARS-CoV-2 alpha variant, achieving an approximately 1000-fold reduction in infectious virions within 12 h. The fibrous nanowire polymer functionalized with zinc nanoclusters was the most effective material against the human influenza A virus strain A/WSN/1933 (H1N1). Conclusions: The materials with Cu nanoclusters can be used with high efficiency to passivate and kill the SARS-CoV-2 alpha variant virions, and Zn nanoclusters modified activated porous membranes for killing human influenza A virus A7WSN/1933 (H1N1) virions. Full article

Conventional fabrication of high-efficiency organic solar cells (OSCs) predominantly relies on vacuum-evaporated metal top electrodes such as Ag and Al, which hinder large-scale industrial production. Gallium-based liquid metals (GaLMs), particularly the eutectic gallium–indium alloy (EGaIn), represent promising candidates to conventional vacuum-evaporated metal top electrodes due to their excellent printability and high electrical conductivity. In this study, we fabricated vacuum-free OSCs based on GaLM electrodes (Ga, EGaIn, and Galinstan) and analyzed the device performances. Rigid devices with EGaIn electrodes achieved a champion power conversion efficiency (PCE) of 15.6%. Remarkably, all-solution-processed ultrathin flexible devices employing silver nanowire (AgNW) bottom electrodes in combination with EGaIn top electrodes achieved a PCE of 13.8% while maintaining 83.4% of their initial performance after 100 compression–tension cycles (at 30% strain). This work highlights the potential of GaLMs as cost-effective, scalable, and high-performance top electrodes for next-generation flexible photovoltaic devices, paving the way for their industrial adoption. Full article

Methylene blue (MB), a widely used industrial dye, is a persistent pollutant with documented toxicity to aquatic organisms and potential health risks to humans, even at ultra-trace levels. Conventional monitoring techniques such as UV–Vis spectroscopy and fluorescence emission suffer from limited sensitivity, typically failing to detect MB below ~10⁻⁷ M. In this study, we introduce a surface-enhanced Raman spectroscopy (SERS) platform based on silver nanowire (AgNW) substrates that enables MB detection over an unprecedented dynamic range—from 1.5 × 10⁻⁴ M down to 1.5 × 10⁻¹⁶ M. Raman mapping confirmed the presence of individual signal hot spots at the lowest concentration, consistent with the theoretical number of analyte molecules in the probed area, thereby demonstrating near-single-molecule detection capability. The calculated enhancement factors reached up to 1.90 × 10¹², among the highest reported for SERS-based detection platforms. A semi-quantitative calibration curve was established spanning twelve orders of magnitude, and this platform was successfully applied to monitor MB degradation during two advanced oxidation processes (AOPs): TiO₂ nanotube-mediated photocatalysis under UV irradiation and atmospheric-pressure dielectric barrier discharge (DBD) plasma treatment. While UV–Vis and fluorescence techniques rapidly lost sensitivity during the degradation process, the SERS platform continued to detect the characteristic MB Raman peak at ~1626 cm⁻¹ throughout the entire treatment duration. These persistent SERS signals revealed the presence of residual MB or partially degraded aromatic intermediates that remained undetectable by conventional optical methods. The results underscore the ability of AgNW-based SERS to provide ultra-sensitive, molecular-level insights into pollutant transformation pathways, enabling time-resolved tracking of degradation kinetics and validating treatment efficiency. This work highlights the importance of integrating SERS with AOPs as a powerful complementary strategy for advanced environmental monitoring and water purification technologies. By delivering an ultra-sensitive, low-cost sensor (<USD 0.16 per test) and promoting reagent-free treatment methods, this study directly advances SDG 6 (Clean Water and Sanitation) and SDG 12 (Responsible Consumption and Production). Full article

The rapidly evolving field of functional yarns has garnered substantial research attention due to their exceptional potential in enabling next-generation electronic textiles for wearable health monitoring, human–machine interfaces, and soft robotics. Despite notable advancements, the development of yarn-based strain sensors that simultaneously achieve high flexibility, stretchability, superior comfort, extended operational stability, and exceptional electrical performance remains a critical challenge, hindered by material limitations and structural design constraints. Here, we present a bioinspired, hierarchically structured core-sheath yarn sensor (CSSYS) engineered through an efficient dip-coating process, which synergistically integrates the two-dimensional conductive MXene nanosheets and one-dimensional silver nanowires (AgNWs). Furthermore, the sensor is encapsulated using a yarn-based protective layer, which not only preserves its inherent flexibility and wearability but also effectively mitigates oxidative degradation of the sensitive materials, thereby significantly enhancing long-term durability. Drawing inspiration from the natural architecture of plant stems—where the inner core provides structural integrity while a flexible outer sheath ensures adaptive protection—the CSSYS exhibits outstanding mechanical and electrical performance, including an ultralow strain detection limit (0.05%), an ultrahigh gauge factor (up to 744.45), rapid response kinetics (80 ms), a broad sensing range (0–230% strain), and exceptional cyclic stability (>20,000 cycles). These remarkable characteristics enable the CSSYS to precisely capture a broad spectrum of physiological signals, ranging from subtle arterial pulsations and respiratory rhythms to large-scale joint movements, demonstrating its immense potential for next-generation wearable health monitoring systems. Full article

Silver nanowires (AgNWs) have garnered significant attention in nanotechnology due to their unique mechanical and electrical properties and versatile applications. This review explores the synthesis of AgNWs, with a specific focus on the utilization of millifluidic flow reactors (MFRs) as a promising platform for controlled and efficient production. It begins by elucidating the exceptional characteristics and relevance of AgNWs in various technological domains and then delves into the principles and advantages of MFRs by showcasing their pivotal role in enhancing the precision and scalability of nanowire synthesis. Within this review, an overview of the diverse synthetic methods employed for AgNW production using MFRs is provided. Special attention is given to the intricate parameters and factors influencing synthesis and how MFRs offer superior control over these critical variables. Recent advances in this field are highlighted, revealing innovative strategies and promising developments that have emerged. As with any burgeoning field, challenges are expected, so future directions are explored, offering insights into the current limitations and opportunities for further exploration. In conclusion, this review consolidates the state-of-the-art knowledge in AgNW synthesis and emphasizes the critical role of MFRs in shaping the future of nanomaterial production and nanomanufacturing. Full article

Copper nanowires (Cu NWs) are considered a promising alternative to indium tin oxide (ITO) and silver nanowires (Ag NWs) due to their excellent electrical conductivity, mechanical properties, abundant reserves, and low cost. They have been widely applied in various optoelectronic devices. In this study, Cu NWs were synthesized using copper chloride (CuCl₂) as the precursor, monoethanolamine (MEA) as the complexing agent, and hydrated hydrazine (N₂H₄) as the reducing agent under strongly alkaline conditions at 60 °C. Notably, this is the first time that MEA has been employed as a complexing agent in this synthesis method for Cu NWs. Through a series of experiments, the optimal conditions for the CuCl₂–MEA–N₂H₄ system in Cu NWs synthesis were determined. This study revealed that the presence of amines plays a crucial role in nanowire formation, as the co-ordination of MEA with copper in this system provides selectivity for the nanowire growth direction. MEA prevents the excessive conversion of Cu(I) complexes into Cu₂O octahedral precipitates and exhibits an adsorption effect during Cu NWs formation. The different adsorption tendencies of MEA at the nanowire ends and lateral surfaces, depending on its concentration, influence the growth of the Cu NWs, as directly reflected by changes in their diameter and length. At an MEA concentration of 210 mM, the synthesized Cu NWs have an average diameter of approximately 101 nm and a length of about 28 μm. To fabricate transparent conductive films, the Cu NW network was transferred onto a polyethylene terephthalate (PET) substrate by applying a pressure of 20 MPa using a tablet press to ensure strong adhesion between the Cu NW-coated mixed cellulose ester (MCE) filter membrane and the PET substrate. Subsequently, the MCE membrane was dissolved by acetone and isopropanol immersion. The resulting Cu NW transparent conductive film exhibited a sheet resistance of 52 Ω sq⁻¹ with an optical transmittance of 86.7%. Full article

Silver/gold (Ag/Au) core–shell nanostructures exhibit tunable plasmonic properties and enhanced catalytic performance, enabling applications across sensing, biomedicine, and environmental remediation. This review presents representative synthetic strategies for fabricating Ag/Au bimetallic core–shell nanostructures with three distinct morphologies: nanospheres, nanocubes, and nanowires. For each architecture, we cover the representative synthetic approaches, such as seed-mediated growth, one-pot synthesis, and evaporation deposition methods, along with their corresponding applications. This review provides discussions on the synthesis methods and applications through specific examples, offering researchers guidance for fabricating Ag/Au core–shell nanostructures with tailored morphologies while addressing major challenges in controlling bimetallic formation. Full article

Semiconductor photonic nanowires are critical components for nanoscale light manipulation in integrated photonic and electronic devices. Optimizing their optical performance requires enhanced photon conversion efficiency, for which a promising solution is to combine semiconductors with noble metals, using the surface plasmon resonance of noble metals to enhance the photon absorption efficiency. Here, we report plasmon-enhanced light emission in a hybrid nanowire device composed of perovskite semiconductor nanowires and silver nanoparticles formed using superfluid helium droplets. A cesium lead halide perovskite-based four-layer structure (CsPbBr₃/PMMA/Ag/Si) effectively reduces the metal’s plasmonic losses while ensuring efficient surface plasmon–photon coupling at moderate power. Microphotoluminescence and time-resolved spectroscopy techniques are used to investigate the optical properties and emission dynamics of carriers and excitons within the hybrid device. Our results demonstrate an intensity enhancement factor of 29 compared with pure semiconductor structures at 4 K, along with enhanced carrier recombination dynamics due to plasmonic interactions between silver nanoparticles and perovskite nanowires. This work advances existing approaches for exciting photonic nanowires at low photon densities, with potential applications in optimizing single-photon excitations and emissions for quantum information processing. Full article

Flexible pressure sensors have garnered significant attention due to their wide range of applications in human motion monitoring and smart wearable devices. However, the fabrication of pressure sensors that offer both high sensitivity and a wide detection range remains a challenging task. In this paper, we propose an AgNW-coated PDMS flexible piezoresistive sensor based on a gradient-wrinkle structure. By modifying the microstructure of PDMS, the sensor demonstrates varying sensitivities and pressure responses across different pressure ranges. The wrinkle microstructure contributes to high sensitivity (0.947 kPa⁻¹) at low pressures, while the PDMS film with a gradient contact height ensures a continuous change in the contact area through the gradual activation of the contact wrinkles, resulting in a wide detection range (10–50 kPa). This paper also investigates the contact state of gradient-wrinkle films under different pressures to further elaborate on the sensor’s sensing mechanism. The sensor’s excellent performance in real-time response to touch behavior, joint motion, swallowing behavior recognition, and grasping behavior detection highlights its broad application prospects in human–computer interaction, human motion monitoring, and intelligent robotics. Full article

Flexible electrochromic devices (ECDs) represent a distinctive category in optoelectronics, leveraging advanced materials to achieve tunable coloration under applied electric voltage. This review delves into recent advancements in electrode materials for ECDs, with a focus on silver nanowires, metal meshes, conductive polymers, carbon nanotubes, and transparent conductive ceramics. Each material is evaluated based on its manufacturing methods and integration potential. The analysis highlights the prominent role of transparent conductive ceramics and conductive polymers due to their versatility and scalability, while also addressing challenges such as environmental stability and production costs. Use of other alternative materials, such as metal meshes, carbon materials, nanowires and others, are presented here as a comparison as well. Emerging hybrid systems and advanced coating techniques are identified as promising solutions to overcome limitations regarding flexibility and durability. This review underscores the critical importance of electrode innovation in enhancing the performance, sustainability, and application scope of flexible ECDs for next-generation technologies. Full article

This study addresses the challenges of efficient, large-scale production of flexible transparent conducting electrodes (TCEs). We fabricate TCEs on polyethylene terephthalate (PET) substrates using a high-speed roll-to-roll (R2R) compatible method that combines gravure printing and photonic curing. The hybrid TCEs consist of Ag metal bus lines (Ag MBLs) coated with silver nanowires (AgNWs) and indium zinc oxide (IZO) layers. All materials are solutions deposited at speeds exceeding 10 m/min using gravure printing. We conduct a systematic study to optimize coating parameters and tune solvent composition to achieve a uniform AgNW network. The entire stack undergoes photonic curing, a low-energy annealing method that can be completed at high speeds and will not damage the plastic substrates. The resulting hybrid TCEs exhibit a transmittance of 92% averaged from 400 nm to 1100 nm and a sheet resistance of 11 Ω/sq. Mechanical durability is tested by bending the hybrid TCEs to a strain of 1% for 2000 cycles. The results show a minimal increase (<5%) in resistance. The high-throughput potential is established by showing that each hybrid TCE fabrication step can be completed at 30 m/min. We further fabricate methylammonium lead iodide solar cells to demonstrate the practical use of these TCEs, achieving an average power conversion efficiency (PCE) of 13%. The high-performance hybrid TCEs produced using R2R-compatible processes show potential as a viable choice for replacing vacuum-deposited indium tin oxide films on PET. Full article