Search Results (6,557)

Micro-electro-mechanical systems (MEMS) sensors offer the benefits of compact size, lightweight design, and low cost, which has led to widespread use in consumer electronics, vehicles, healthcare, defense, and communications. As their performance has improved, MEMS sensors have also found applications in oil exploration and geophysical studies. Pressure and temperature measurements during hydraulic fracturing have long been employed to improve downhole conductivity during oil and gas extraction. Nevertheless, the development of high-precision MEMS sensors for oil exploration remains an active area of research. This paper presents the design, fabrication, packaging, and characterization of a silicon-on-insulator (SOI) MEMS piezoresistive pressure sensor integrated with a temperature sensor. It also describes the design of a chamber intended to emulate conditions at the bottom of oil exploration wells. The sensors were successfully designed and fabricated on the basis of physics-based simulations, deep reactive ion etching and anodic bonding. The pressure sensors, together with the signal-conditioning system, exhibited a linear response with a sensitivity of 0.0268 mV/V/MPa and maximum hysteresis of 5.3%. Full article

Inspired by the growing demand for small and effective optoelectronic devices, this paper presents a simulation-based analysis of InGaN/GaN quantum dot light-emitting diode, focusing on the effects of systematic variation in both anode and cathode contact regions, as well as overall device size. Two-dimensional simulations using APSYS software were used to examine the impact of scaling the device dimensions as well as the individual contact dimensions on significant performance parameters like internal quantum efficiency (IQE), optical output power, and current-voltage (IV) response. We simulated five LED device sizes that is 50 × 50 µm², 100 × 100 µm², 200 × 200 µm², 300 × 300 µm², and 400 × 400 µm². As device size grows, so does the total current at each voltage. The highest current measurement is achieved by the device with dimensions 400 × 400 µm² while the lowest is observed on the device with dimensions 50 × 50 µm². In addition to changing the device dimensions, we ran extensive simulations on the sizes of p-type and n-type contacts. Notable changes were seen in the efficiency, optical power, and emission profile of the p-contact. The behavior of p-side contacts from 0 to 50 µm was the same, while contacts between 60 and 100 µm showed significant differences. The significant performance parameters were unaffected by changes to n-contact dimensions. The results of this study illustrate how the configuration of contacts and dimensions greatly influences the electrical and optical performance of quantum dot light-emitting diode. The results are believed to be helpful to researchers working on the design of next-generation compact and efficient solid-state lighting devices. Full article

Magnesium–air battery anodes suffer from self-corrosion, chunk effect, and poor removal of discharge products, resulting in low anode efficiency. Although various modification strategies for Mg anodes have been reported, the effects of Ge content on the microstructure and performance of AZ61 Mg anodes at a fixed La content remain unclear. In this study, AZ61-1La-xGe alloys (x = 0, 0.25, 0.7, and 0.9 wt.%) were prepared, and their microstructure, corrosion behavior, and discharge performance after solution treatment were systematically investigated. Among them, AZ61-1La-0.7Ge exhibited the best overall performance, mainly due to the appropriate addition of Ge, which promoted a uniform distribution of secondary phases and grain refinement, thereby suppressing self-corrosion and chunk effect, improving discharge uniformity, and enhancing anode utilization by facilitating the formation of a loose discharge product layer. This study provides a basis for optimizing the Ge content in La-modified AZ61 Mg alloy anodes. Full article

The secondary effluent from printing and dyeing wastewater contains recalcitrant organic pollutants, such as azo dye derivatives. Their persistence in aquatic environments not only creates ecological risks but also hampers the high-value reuse of reclaimed water. This study investigated the influence of typical binary anions on the degradation performance of low-concentration azo dye wastewater using a Ti/RuO₂-IrO₂ anode electrochemical oxidation system. The results demonstrated that maximum COD removal efficiency could reach 50.22%, and the controlling factors synergistically regulated the contribution and competition between Reactive Chlorine Species and free radicals. This led to a characteristic “rapid rise–decline–slow rebound” phenomenon in the COD removal rate, with the inflection points co-influenced by the current density, conductivity, and binary anion ratio of the electrochemical process. Furthermore, it alters the degradation pathway of the azo dye to “azo bond cleavage → demethylation/desulfonation → dehydroxylation/deamination oxidation → benzene ring opening”. Within a fixed duration of 60 min, the Response Surface Methodology model identified the optimal COD degradation conditions as follows: current density of 19.72 mA/cm², Cl⁻/SO₄²⁻ ratio of 5.40, and conductivity of 8.30 mS/cm. This research elucidates the differences between the electrochemical oxidation degradation pathway of low-concentration azo dye wastewater under the regulation of typical binary anions and the conventional pathway. It also reveals the regulatory effects of current density, conductivity, and binary anion ratio on the degradation patterns. Full article

The recent endeavor to establish a sustainable society, with respect to environmental protection and occupational health prevention, necessitates the development of environmentally friendly anodizing electrolytes. In addition, these electrolytes should be composed of biocompatible organic acids derived from renewable sources. In response to these challenges, there is a need to seek environmentally conscious alternatives to the widely used sulfuric acid anodization electrolyte. Accordingly, a comparative study was performed on the anodic polarization of AA2024-T3 aircraft alloy samples for 30 min at 0 or 20 °C. The respective electrolytes were composed of 0.5 M solutions of oxalic, citric, tartaric acids, or glycine. The comparative analysis included optical metallographic microscopy (OMM), scanning electron microscopy (SEM), color and wettability characterization, chemical composition analysis by X-ray photoelectron spectroscopy (XPS), and assessment of the corrosion-protective properties of the obtained layers. The latter were defined using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization scanning (PDS) after 24 h of exposure to a 0.5% NaCl solution. Among the most important conclusions is that the barrier properties of the layers obtained in citric and tartaric acid electrolytes remarkably exceed those of the film obtained in oxalic acid. The use of glycine does not result in film formation at all. The process temperature had a weaker effect than the electrolyte composition. The recent commitment to building a sustainable society, emphasizing environmental protection and occupational health, requires the development of eco-friendly anodization processes. These electrolytes should use biocompatible organic acids from renewable sources. Meeting these needs demands alternatives to the commonly used sulfuric acid anodization. Therefore, a comparative study was conducted on the anodic polarization of AA2024-T3 aircraft alloy samples for 30 min at 0 or 20 °C. The electrolytes consisted of 0.5 M solutions of oxalic, citric, tartaric acids, or glycine. Analytical methods included optical metallographic microscopy (OMM), scanning electron microscopy (SEM), color and wettability assessment, chemical composition analysis by X-ray photoelectron spectroscopy (XPS), and evaluation of corrosion resistance. The latter was measured using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization scanning (PDS) after 24 h in 0.5% NaCl solution. Key findings showed that barrier properties of the citric and tartaric acid layers substantially surpassed those of oxalic acid films. Glycine did not produce a film. The electrolyte composition had a greater impact than process temperature. Full article

Developing sustainable electrode materials from renewable biomass is important for improving the environmental sustainability of lithium-ion batteries (LIBs). Sugarcane bagasse lignin, an abundant agricultural byproduct, is a promising precursor for lignin-derived carbon anode materials, yet systematic comparative studies on catalyst-dependent structure evolution and LIB performance remain limited. In this study, lignin extracted from sugarcane bagasse by an ethanosolv process was converted into Fe- and Ni-catalyzed lignin-derived carbon materials via catalytic pyrolysis at 900 °C. The effects of catalyst type, metal-to-lignin ratio, and pyrolysis holding time on textural properties, structural features, and electrochemical behavior were systematically investigated. Among the studied conditions, the Fe-catalyzed sample prepared at a metal-to-lignin ratio of 1:2.5 and a holding time of 3 h (GLKL-2.5Fe-3h) exhibited the highest BET surface area (332.71 m² g⁻¹) and the most developed porous morphology. SEM, TEM, Raman, and XRD analyses indicated catalyst-dependent differences in pore development, carbon domain morphology, and local graphitic ordering, with Fe- and Ni-catalyzed samples following distinct structural evolution pathways. Electrochemical testing showed that GLKL-2.5Fe-3h delivered the highest initial discharge capacity (759 mAh g⁻¹), retained 165 mAh g⁻¹ after 500 cycles, and exhibited more favorable rate performance and lower apparent interfacial resistance than the other tested samples under the same conditions. In contrast, the Ni-catalyzed and solvothermally treated samples showed lower capacity retention and/or less favorable electrochemical behavior. These results demonstrate the strong effect of catalyst type on the structure-performance relationship of bagasse lignin-derived carbon anodes and support Fe-catalyzed lignin-derived carbon as a promising sustainable anode candidate for LIB applications. Full article

Modern bioimplants increasingly depend on surface-engineered functionality to elicit adaptive biological responses. One promising strategy involves the electrodeposition of bioresponsive elements such as magnesium (Mg), which plays a critical role in osseointegration. In this study, we present a novel approach for modifying anodized zirconia nanotubes (ZrNTs) via Mg decoration using electrochemical deposition. A controlled pulsed cathodic linear sweep protocol was employed to control Mg deposition behaviour, enabling reduced clustering and improved spatial distribution. Notably, ultraviolet (UV) irradiation was found to influence Mg adsorption dynamics, revealing a distinct pattern of interaction. Comprehensive surface characterization was conducted to assess nanotube morphology, Mg adherence, and distribution. These modified surfaces were subsequently evaluated for their potential in further functionalization, targeting surface chemistries conducive to biomaterial viability. The biomineralization capacity of Mg-decorated ZrNTs was systematically investigated using electrochemical impedance spectroscopy (EIS) and Tafel analysis, demonstrating enhanced apatite formation and improved corrosion resistance. This work establishes Mg decoration of ZrNTs as a viable route for developing bioactive, corrosion-resistant implant surfaces. Full article

Aqueous zinc-ion batteries (AZIBs) are promising for large-scale grid storage due to inherent safety, low cost, environmental compatibility, high theoretical capacity (820 mAhg⁻¹), and suitable redox potential (−0.763 V vs. SHE). However, practical deployment is hindered by coupled challenges at the zinc anode–hydrogen evolution, dendrite growth, and corrosion/passivation, which severely limit cycle life and coulombic efficiency. This review systematically summarizes key advances in AZIB research. It first elucidates working principles and four cathode energy storage mechanisms: Zn²⁺ insertion/extraction, H⁺/Zn²⁺ co-insertion, chemical conversion, and dissolution/deposition. Second, it examines four mainstream cathodes (manganese-based, vanadium-based, Prussian blue analogs, and organic compounds), analyzing performance bottlenecks and corresponding optimization via structural modification. Third, it explores functional mechanisms of advanced separators (polymer, inorganic/ceramic composite, MOF-based, and cellulose-based) in regulating uniform Zn²⁺ deposition and suppressing dendrites. Fourth, it summarizes anode optimization strategies: artificial protective layers for interface stabilization, electrolyte additives to modulate Zn²⁺ solvation/deposition, and 3D porous structures to reduce local current density and provide nucleation sites. Finally, key scientific challenges and future directions are discussed—multi-strategy synergy, in situ characterization, practical battery construction, and sustainable technological development, offering theoretical guidance for advancing AZIBs toward large-scale applications. This review aims to provide a comprehensive perspective spanning from materials to systems, and from mechanisms to applications. Its core objective is not merely to list the types of cathode materials, but to establish a logical bridge directly connecting “key challenges” to “optimization strategies,” with a particular emphasis on the issues and solutions related to the cathode side. Full article

Supercapacitors (SCs) are highly attractive energy storage devices, and modern research is focused on using waste materials to reduce environmental impact. This study processed biowaste from local brewery production to produce a highly specific mesoporous activated carbon (AC) for SC electrode scaffolds. Polyaniline (PANI) was synthesized and incorporated into the AC scaffold, thereby enhancing performance. The AC and PANI combination (ACP) achieved a specific capacitance of 173.7 F/g at 1 A/g, with 92% retention after 5000 cycles. Using NdFeB (ACN) particles, the anode showed a specific capacitance of 127 F/g and over 99% retention. An asymmetrical ACN//ACP cell demonstrated promising performance with 70% efficiency. This study highlights the potential of using biowaste for high-performance SC electrodes and the effective synergy between AC and PANI. Full article

This study presents a low-cost, small-scale single-chamber microbial fuel cell (MFC) toxicity biosensor fabricated on a printed circuit board (PCB) and a 3D-printed chamber with a volume of 120 μL. The anode consists of a screen-printed carbon electrode on the PCB, while the air cathode is a carbon paper electrode. To address poor adhesion of microorganisms to the smooth anode surface, femtosecond laser processing was used to fabricate a micropore array with 40 μm pores on the electrode. This method can create micropores on the anode surface without damaging the screen-printed electrodes, the PCB substrate, or the pads. These micropores increase the anode’s surface area and hydrophilicity, allowing more microbial coatings to firmly adhere to its surface. In this study, the MFC utilised Rhizobium rosettiformans W3, extracted from activated sludge at a wastewater treatment plant, as the anode microorganism. Its aerobic nature simplifies the design of MFCs, enabling a single-chamber structure and miniaturisation. Using formaldehyde solution as a toxicity sample to test the biosensor’s performance, a 0.1% concentration significantly reduced the sensor’s output power. Full article

Background/Objectives: Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders in childhood and it tends to remain during adulthood. It not only affects cognitive abilities and behavior but also often presents emotional disturbances and alterations in the perceived quality of life. These symptoms are primarily related to dysfunctions in the ventromedial and dorsolateral prefrontal network. The main objective was to evaluate the feasibility and explore the initial outcomes of an integrated protocol combining neuropsychological treatment and transcranial direct current stimulation (tDCS). Methods: This study presents a single-case experimental A-B design of a 21-year-old woman, diagnosed with predominantly inattentive ADHD, treated at the University Psychology Clinic of Loyola Andalucía University. The treatment was carried out twice a week for 5 weeks (10 sessions in total), with 20 min of anodal tDCS at F3 and cathodal tDCS at F4 (2 mA), while digital neurorehabilitation exercises and psychotherapeutic support were provided. Results: An overall significant improvement was observed in cognitive functions (p = 0.008), with clinically significant gains in cognitive flexibility, visual working memory, and planning. Mixed results were found in inhibition, with improvement in interference control but no change in response inhibition. No significant changes were observed in sustained attention, auditory working memory, or processing speed. In terms of emotional state, an overall improvement was noted (p = 0.046), particularly in depression symptoms and perceived quality of life related to physical and psychological health. However, no significant changes were observed in anxiety symptoms or in areas related to the environment and social relationships. These findings reflect pilot-level evidence of clinical change within a feasibility framework. Conclusions: The combined treatment was found to be safe and feasible, showing promising preliminary improvements in cognitive and emotional domains. As a single-case study, these results serve as hypothesis-generating evidence for future controlled trials. Full article

Nickel-oxide-based anodic electrochromic materials are extensively utilized as counter electrodes in smart window systems due to their reversible optical response during ion insertion and extraction. This study systematically investigates the influence of substrate temperature on the electrochromic properties of sputtered nickel-tungsten oxide thin films. The deposited thin films exhibit an amorphous structure. An increase in substrate temperature results in a decrease in nickel-vacancy concentration. Raman spectroscopy verifies the amorphous nature. Films deposited at lower substrate temperatures exhibit superior electrochromic performance, characterized by improved optical contrast of 64% and rapid coloration (2.21 s) and bleaching (0.93 s) dynamics. The enhanced performance is ascribed to the disordered amorphous structure and the existence of enough nickel vacancies, which collectively facilitate efficient and reversible lithium-ion transfer. This study illustrates that meticulous regulation of substrate temperature is an effective method for adjusting the microstructure and defect chemistry of nickel–tungsten oxide thin films, rendering them appropriate as effective counter electrodes for energy-efficient smart window applications. Full article

Anode-less battery architectures, which eliminate the host anode material, have attracted considerable attention as a promising approach to increase energy density, simplify cell manufacturing, and improve safety in next-generation energy storage systems. This review provides a structured and integrative overview on the current research landscape of anode-less cells, spanning both liquid- and solid-electrolyte technologies. It first introduces the fundamental principles, key advantages, and inherent challenges of the anode-less concept. Advanced characterization techniques, including electrochemical, interfacial, morphological, and operando approaches, are then discussed as essential tools for probing metal plating/stripping behavior and degradation mechanisms. The core of the review examines how system design governs performance, addressing strategies for liquid electrolytes, including current collector design, electrolyte formulation, and deposition control, as well as solid electrolytes, with an emphasis on interfacial engineering, fundamental limitations, and extensions to Na- and K-based batteries. By integrating insights across these systems, the review identifies critical challenges, including unstable solid-electrolyte interphases, dendrite formation, and interfacial contact loss. Finally, a development pyramid is introduced as a conceptual framework linking fundamental research to practical implementation, outlining key priorities from interface control and full-cell compatibility to long-term reliability while also highlighting industrial pathways toward hybrid and fully solid-state anode-less batteries. Full article

To support the development and computer simulation of radio frequency (RF) and microwave (MW) thawing processes, this study characterized the dielectric properties and penetration depth of chicken breast across a frequency range of 10–3000 MHz and temperatures from −20 °C to 10 °C. The influence of three RF anode voltages and four MW power levels on heating rates was also evaluated. Results showed that both the dielectric constant and loss factor decreased with increasing frequency, with the most significant reduction occurring between 10 and 60 MHz. In contrast, these properties increased with temperature, exhibiting a sharp rise during the phase transition zone (−5 to 0 °C). Penetration depth decreased with frequency and was consistently higher under RF than MW exposure. High-precision regression models (R² > 0.97) were established to describe these relationships. RF heating achieved more uniform temperature distribution compared to MW, which showed pronounced center-corner temperature differences. By integrating experimental measurements with mathematical modeling, this work provides key insights and reliable data for optimizing RF and MW thawing strategies in industrial applications. Full article

Lithium–sulfur (Li–S) batteries have emerged as a promising next-generation energy storage solution as the capacity demands on lithium-ion systems begin to exceed practical limits. In a global push for renewable energy and sustainable practices, Li–S technology offers several compelling advantages. Both lithium and sulfur are relatively inexpensive (especially compared to the transition metals used in lithium-ion cells), and Li–S batteries are easier and less costly to recycle. Moreover, Li–S chemistry carries a theoretical energy density about five times greater than that of current lithium-ion batteries, making it attractive for high-energy-density applications. Because of these advantages, research interest in Li–S batteries remains high despite significant challenges that still limit their performance and lifespan. However, despite these advantages, several fundamental challenges limit the practical deployment of Li–S batteries, including the polysulfide shuttle effect, large volume expansion of sulfur during cycling, low intrinsic electrical conductivity of sulfur and its discharge products, and instability of the lithium metal anode caused by dendrite formation. This paper explains the working principles of Li–S batteries, analyzes the key challenges and recent achievements in their development, and surveys various mechanical engineering applications for which Li–S batteries are being explored, as well as prospects for their future commercialization and sustainability. Full article