Search Results (1,149)

The increasing worldwide demand for sustainable energy and effective waste management has heightened interest in solutions. Microbial fuel cells (MFCs) represent a potential category of bioelectrochemical systems that directly transform the chemical energy contained in organic waste into electrical energy via the metabolic processes of electroactive microorganisms. In the last twenty years, significant advancements have occurred in the comprehension of extracellular electron transfer (EET) mechanisms, biofilm formation, microbial community dynamics, electrode material engineering, and reactor design, resulting in marked enhancements in power density and wastewater treatment efficacy. Despite these breakthroughs, the extensive deployment and commercialization of MFC technology are constrained by various hurdles, including inadequate energy recovery, elevated material and fabrication expenses, operational instability, and the intricacies of system scale-up. This cutting-edge analysis offers a thorough evaluation of recent advancements in MFCs and their incorporation with sophisticated technology for waste management and energy generation. Focus is directed towards essential bioelectrochemical principles, microbial and biofilm engineering techniques, sophisticated electrode and membrane materials, reactor designs, and hybrid MFC systems integrated with anaerobic digestion, microbial electrolysis, and advanced oxidation methods. Ultimately, emerging trends, significant knowledge deficiencies, and future research goals are defined to inform the advancement of next-generation MFC systems that support circular economy and net-zero energy initiatives. Full article

In this work, we employed an easy hydrothermal method to prepare CuO and ZnO, as well as the prepared composite nanostructured electrodes of CuO@ZnO for supercapacitor applications. The systematic electrochemical performance evaluation of the prepared materials was conducted by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). CuO@ZnO nanocomposite reflected the best charge storing behavior with a specific capacitance of 513 F/g, followed by pristine CuO (190 F/g) and ZnO (416 F/g). The composite also demonstrated 25.67 Wh/kg and 400 W/kg for energy density and power density, respectively, suggesting improved electrochemical performance. Besides, the areal and volumetric capacitances were 0.77 F/cm² and 4.81 F/cm³, respectively, supported by the structural integrity and enhancement in electroactive materials utilization of the electrode material. Kinetic analysis showed that b values of the samples had mixed capacitive/diffusion-controlled charge storage, while higher diffusion coefficients and standard rate constants were apparent for ion transport or redox kinetics. EIS results showed a 2.14 Ω solution resistance, indicative of a decreased electrical resistivity. An asymmetric supercapacitor device fabricated by CuO@ZnO as the positive electrode and activated carbon (AC) as the negative electrode provided the specific capacitance of 48.57 F/g, energy density of 15.17 Wh/kg, and power density of 535 W/kg. After 10,000 cycles, the capacitance of the device was 76%, indicating good long-term stability. Full article

In the present study, Fe₃O₄@hydrothermal carbon was prepared successfully using rice straw waste. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis confirmed that the material had rich and strong redox-active centers on its surface, indicating that it has potential to be used as a redox mediator for electron transfer. Fe₃O₄@hydrothermal carbon was added into the anaerobic sludge treatment system for the collaboration of dye decolorization. The results showed that azo dye decolorization efficiency reached the maximum value (98.3%) with the presence of Fe₃O₄@hydrothermal carbon, which was 16.6% higher than control reactor (without Fe₃O₄@hydrothermal carbon added). In addition, Fe₃O₄@hydrothermal carbon exhibits good reusability and the dye decolorization rates in the “anaerobic sludge–material” combining system were significantly higher than that in the “sludge-alone” system during the semi-continuous wastewater treatment process. Mechanistic investigations revealed that the enhanced decolorization is driven by a synergistically constructed interspecies electron transfer pathway. Specifically, the addition of Fe₃O₄@hydrothermal carbon improved the formation of the extracellular polymeric substance (EPS), which had positive effects on sludge stability and its interaction with the material. CV and electron transport system (ETS) activity analysis showed that the sludge exhibited high electrochemical activities with the support of the material, which led to a high electron transfer efficiency between the electron-donating and accepting microbial pairs in the treatment system. The high-throughput sequencing analysis showed that the structure of the microbial community changed during the semi-continuous treatment process; Megasphaera and Clostridium accounted for more than 87.5% of the total abundance of the bacterial community in the anaerobic sludge with material addition. Driven by the material-mediated process, these enriched functional taxa exhibited a high electron transfer efficiency between electron-donating and accepting pairs, accelerating the catalytic cleavage of azo bonds and ultimately improving the overall anaerobic treatment performance. Full article

Sensors and biosensors designed for biomarker detection in biological samples often suffer from performance loss caused by surface fouling, interface blocking, and matrix interference. Although these effects are frequently discussed separately, in real sensing systems they are strongly interconnected and they determine analytical reliability, especially in body fluids like serum, plasma, whole blood, sweat, and other complex media. This review provides a practical and mechanism-oriented overview of how these processes originate, how they differ, and how they ultimately lead to signal drift, reduced sensitivity, false-positive responses, and shortened sensor lifetime. We first discuss the molecular origins of interface failure, including protein adsorption, conditioning film formation, nonspecific binding, ionic strength effects, pH fluctuations, viscosity-related diffusion changes, and electroactive interferents. The impact of these phenomena is then compared across major sensing platforms, including electrochemical, potentiometric, optical, capacitive sensors, field-effect transistors and wearable biosensors. A central part of this review focuses on practical prevention strategies already employed in real biomarker sensing platforms. These include hydration-driven antifouling coatings, zwitterionic and hydrogel interfaces, post-immobilization blocking with bovine serum albumin, mercaptohexanol and ethanolamine, ionophore and membrane engineering in ion-selective electrodes, hydrophobic solid-contact layers for water-layer suppression, regeneration workflows, membrane and microfluidic pre-treatment, and AI-assisted drift correction. By combining advances in materials engineering, surface chemistry, sample handling, and algorithmic correction, this review highlights strategies to improve sensor stability in complex biological fluids. Overall, it offers a practical guide for developing next-generation low-fouling, drift-resistant, and self-correcting sensing systems for reliable biomarker analysis at the point of care. Full article

Artificial muscles are an emerging class of actuators designed to mimic the compliant, efficient, and versatile behavior of biological muscles for fields including the following: soft robotics, prosthetics, wearable enhancements, haptic interfaces, and biomedical devices. These systems encompass various actuation mechanisms, including pneumatic, hydraulic, thermal, ionic, electrochemical, and electrostatic. Each with distinct tradeoffs in voltage, strain, output force, bandwidth, efficiency, and manufacturability. Among them, electrostatic actuators have attracted increased attention due to their fast response times, high energy densities, strong compatibility with soft materials, and scalability from microscale devices to large-area and stacked actuators. However, challenges such as dielectric breakdown, material fatigue, and fabrication complexity continue to limit widespread deployment. This review presents a structured classification of various artificial muscle technologies and an in-depth examination of electrostatic actuators including dielectric elastomers, electrostrictive and ferroelectric polymers, liquid crystal elastomers, electrostatic film motors, stacked architectures, and microscale/milliscale devices. In this review the operating principles, materials, architectures, performance characteristics, and failure modes of electrostatic actuators will be discussed. Additionally, a comparison will highlight tradeoffs across actuator families based on metrics such as voltage, force, strain, bandwidth, and manufacturability. Lastly, we outline future research directions in materials, physics-informed modeling, system integration, and scalable fabrication necessary to advance electrostatic artificial muscles toward practical, real-world deployment. Full article

Microbial fuel cells (MFCs) are promising bioelectrochemical systems for simultaneous wastewater treatment and energy recovery. However, their practical application is still limited by insufficient power output and weak transient energy-supply capability under fluctuating operational conditions. Herein, a bifunctional CF/MXene/FeS composite anode was fabricated through a one-step hydrothermal strategy to simultaneously enhance electricity generation and capacitive charge storage in MFCs. Unlike conventional bioanode modifications that primarily target conductivity enhancement alone, the constructed hierarchical composite integrates conductive MXene nanosheets and electroactive FeS phases to synergistically improve extracellular electron transfer and interfacial charge-storage behavior. The modified electrode exhibited enhanced surface roughness, abundant electroactive sites, and improved biofilm-supporting interfaces. Benefiting from the integrated conductive and electroactive composite framework, the CF/MXene/FeS anode achieved a maximum power density of 1.69 W/m², which was 70.7% higher than that of pristine CF, together with an increased open-circuit voltage of 0.711 V. In addition, the composite electrode delivered a high total charge density of 13,192.09 C/m² under the C900/D900 condition. Microbial community analysis further revealed substantial enrichment of electroactive bacteria, with the relative abundance of Geobacter increasing from 0.0058% to 22.84%. This work provides a promising strategy for integrating electricity generation and transient energy storage in bioelectrochemical systems, offering potential applications for energy-buffered MFCs under fluctuating power-demand conditions. Full article

Transition-metal oxide/layered double hydroxide (LDH) electrodes often suffer from insufficient utilization of active sites, sluggish electron/ion transport, and limited cycling stability at high rates. Here, La-doped ZnCo₂O₄/MnCo-LDH nanoflowers serve as the positive electrode and Ti-supported Sb-doped SnO₂ (Ti/Sb-SnO₂) serves as the negative electrode for constructing an asymmetric supercapacitor. A stepwise hydrothermal route, La-doping regulation, and ethylenediamine-assisted morphology control transform stacked nanosheets into open porous nanoflowers with a specific surface area of 382.5 m² g⁻¹, thereby exposing more electroactive sites and shortening OH⁻ diffusion pathways. La³⁺-induced lattice distortion and defect-related oxygen species further tune the electronic structure and improve interfacial charge-transfer kinetics. The optimized La-ZnCo₂O₄/MnCo-LDH electrode delivers 2130 F g⁻¹ at 1 A g⁻¹ and retains 1993 F g⁻¹ after 10,000 cycles at 3 A g⁻¹. The Ti/Sb-SnO₂ negative electrode provides 673 F g⁻¹ at 1 A g⁻¹ and 302 F g⁻¹ at 15 A g⁻¹. The assembled device operates stably from 0 to 1.8 V in 2 M KOH and achieves 69 Wh kg⁻¹ and 13,500 W kg⁻¹. Full article

Accurate quantification of glucose is vital for quality control in the food industry. While earth-abundant Cu has emerged as a promising candidate for non-enzymatic electrochemical sensing, conventional electrode fabrication relying on powder coating with polymeric binders inevitably buries active catalytic sites and impedes both electron transfer and mass transport. In this study, a binder-free, self-supporting Cu nanoparticles/Ni foam (Cu NPs/NF) electrode was developed via a facile one-step hydrothermal method. Benefitting from the enhanced charge-transfer efficiency and a substantially enlarged electrochemical active surface area, the Cu NPs/NF-based electrochemical glucose sensor exhibited a wide linear detection range (0.25–3310.52 μM), a high sensitivity of 7000 μA mM⁻¹ cm⁻², a low detection limit of 0.32 μM, and a rapid response time of 3 s. Furthermore, the developed Cu NPs/NF electrode displayed favorable reproducibility, storage stability, and high selectivity against common interferents present in food matrices, demonstrating its reliability for practical applications. The feasibility of the proposed sensor was successfully validated in real beverage samples. Given the simplicity of the one-step hydrothermal synthesis and the portability afforded by the self-supporting electrode architecture, this Cu NPs/NF electrode emerges as a highly attractive candidate for commercial glucose sensors. Beyond glucose, the design strategy can be readily extended to the detection of other electroactive food-quality markers, enabling the broader applicability of this electrode platform in comprehensive food analysis. Full article

Metalloporphyrins play an important role in biomedicine, catalysis, and energy, among other fields, due to their structural complexity and functional diversity. In this study, GO was used as the precursor support and chitosan was employed to reduce and functionalize GO into chitosan-functionalized rGO. Furthermore, metalloporphyrins were covalently linked to the amino side chains of chitosan via an amide crosslinking method, and a series of metalloporphyrin–chitosan-functionalized rGO nanocomposites were designed and synthesized. A set of poly(metalloporphyrin–chitosan)-functionalized rGO working electrodes was constructed by drop-coating onto glassy carbon electrodes, and their electrocatalytic performance toward dopamine was investigated in PBS solution. Finally, zinc(II) porphyrin, with the best performance, was selected as the core catalytic unit to fabricate an enzyme-free dopamine sensor. Under optimal working conditions, the sensor exhibited a sensitivity of 0.30 mA mM⁻¹cm⁻², a linear detection range of 0.001~1.0 mM, and a low detection limit of 0.05 μM (S/N = 3). The sensor showed anti-interference ability against various interfering ions and electroactive substances, as well as good stability and repeatability. Full article

Nanomaterial-based biosensors have advanced analytical methodologies by enhancing signal transduction, interfacial reactivity, and molecular recognition across diverse sensing platforms. In parallel, the diversity of nanomaterial compositions, architectures, and interfacial designs has expanded the range of available sensing strategies and performance outcomes. This review addresses limitations through a structure–property–function framework that links nanomaterial characteristics to sensing behavior, performance determinants, and application-specific requirements. Within this framework, nanomaterials are classified according to their dominant functional roles in biosensing, including plasmonic, electroactive, fluorescent and quantum-confined, porous, and hybrid architectures. The influence of morphology, surface chemistry, conductivity, and interfacial design on electrochemical, optical, and hybrid transduction mechanisms is critically examined, and key performance parameters, including sensitivity, selectivity, limit of detection, response time, stability, and reproducibility, are discussed in relation to material properties and sensing configuration. Recent advances in clinical biomarker detection, pathogen and nucleic acid analysis, and environmental and food safety monitoring are also evaluated to illustrate how nanomaterial design is tailored to different analytical contexts. Current limitations related to reproducibility, interface engineering, long-term stability, and scalable device integration are highlighted, together with future directions for the rational development of robust and application-oriented biosensor platforms. Full article

Polymeric fibers represent a vital class of functional materials due to their versatile properties, such as wide availability, low cost, recyclability, biodegradability, and excellent mechanical and chemical stability. Polymer fibers can be fabricated at both micro- and nanoscale dimensions using a variety of processing techniques. This review provides a comprehensive overview of the principal methods employed for polymer fiber preparation, including electrospinning, melt and solution blowing, dry and wet spinning, template synthesis, phase separation, and self-assembly. The technical principles, as well as the advantages and limitations, of each technique are systematically discussed. The review also explores polymeric fibers as smart materials for actuation applications. Particular focus is given to stimulus-responsive fiber systems such as shape memory fibers, hydrogel fibers, liquid crystal fibers, and electroactive polymers. Overall, this review establishes a coherent framework linking polymer fiber fabrication strategies with structure–property–function relationships, offering practical guidance for material selection and accelerating the development of next-generation smart polymer fibers for advanced actuation and multifunctional applications. Full article

Extracellular polymeric substances (EPSs) are high-molecular-weight biopolymers secreted by microorganisms, showing great potential for bioremediation. However, comprehensive analyses of the development context and quantitative research on the overall trends of EPSs in bioremediation are lacking. This study conducted a systematic bibliometric analysis of microbial EPS research using VOSviewer and CiteSpace. Keyword burst and thematic evolution analysis indicate a distinct thematic shift: early research focused on “structural characterization and adsorption mechanisms of EPSs”, whereas current hotspots highlight interactions with emerging pollutants (e.g., microplastics, antibiotics, and antibiotic resistance genes (ARGs)). EPSs significantly influence the environmental fate and removal efficiency of emerging pollutants through multiple pathways, including physical adsorption, chemical complexation, photocatalytic degradation, and electron transfer. For microplastic remediation, EPSs mediate hetero-aggregation, surface modification, and biodegradation processes. In antibiotic removal, EPSs function through biosorption, biodegradation, and photosensitized degradation. Regarding the mitigation of ARGs, EPSs can either suppress or facilitate their horizontal gene transfer, depending on their composition and environmental conditions. Additionally, as electroactive medium, EPSs play a crucial role in facilitating electron transfer, enhancing nitrogen removal, and promoting heavy metals reduction. This study systematically reviewed the current status and research hotspots of EPSs in bioremediation. However, practical applicability remains constrained by challenges such as low production yield and high costs. Future directions to address these limitations are also outlined to guide further development. Full article

This study introduces a four-channel millifluidic microbial electrochemical reactor (mMER) designed for parallel screening of cathodically active microbial communities. This platform integrates electrochemical control with online optical density (OD) monitoring, enabling simultaneous tracking of biomass-associated OD development and current response in four separate culture systems. The system’s performance was initially validated through photometric calibration and biocompatibility tests, leading to the development of a standardized workflow for cathodic enrichment protocols of soil microbial communities. Using this system, a cathode potential of −0.4 V (vs. quasi-reference electrode) was identified as effective and applied to four different soil samples, revealing variations in their electrochemical responses. Based on combined OD and current measurements, a time-resolved ΔOD/ΔQ analysis was introduced to compare biomass-associated electrochemical response behavior during enrichment. This analysis revealed distinct temporal response characteristics among soil microbial communities, including early, delayed, and sustained responses observed under cathodic cultivation conditions. Open-circuit potential measurements, conducted after enrichment, provided additional electrochemical characterization of the enriched systems. Among all samples, the microbial community from a Neolithic earthwork site (Niedersickte, Germany, sample HB51) demonstrated the most stable relationship between cathodic current consumption and OD development during enrichment. The mMER platform offers a valuable tool for the comparative screening of electroactive microbial communities from complex environmental samples. Full article

A livestock farm in southern Taiwan produces wastewater with high concentrations of nitrogen and organics, which inhibit anaerobic methanogens and limit the efficiency of its biogas system. To enhance energy recovery, this study developed a liter-scale microbial fuel cell (MFC) system aimed at harvesting electricity from livestock wastewater, serving as a supplementary energy recovery pathway alongside the biogas process. According to the five analyses, the chemical oxygen demand (COD) of raw wastewater ranged from 14 to 21 g L⁻¹, with acetate concentrations ranging between 40 and 112 mM. Propionate and butyrate were consistently below 32 mM and 18 mM, respectively. Ammonium ranged from 1.1 to 1.7 g-N L⁻¹, indicating the wastewater’s high organic load and elevated nitrogen content. Two liter-scale MFCs, ch5 and ch7, were operated for over 70 d. From days 7 to 28, both MFCs employed a fill-and-draw mode, achieving optimal COD removal exceeding 80%. After resolving leakage issues between days 30 and 40, the system was restarted on day 40, yielding 76% (ch5) and 82% (ch7) of COD removal. Continuous operation began on day 59, and both reactors maintained COD removal rates above 80% for most of the subsequent two-week period. The best power outputs for ch5 and ch7 reached 1.11 and 0.82 W m⁻³, respectively. Although both liter-scale reactors achieved COD removal and measurable power output, the most important finding was obtained from the inoculum comparison experiments. After 54 days of acclimating to raw wastewater solids, no significant current was observed. In contrast, digestate solids acclimated with carbon powder for 22 d produced a peak current of 42.5 A m⁻³ at 147 h, with COD removal rates of 67–73% and complete removal of organic acids. The key conclusion of this study is that anaerobic digestate exhibits electroactive microbial potential, whether operated in liter-scale reactors or acclimated with carbon powder. Further investigation into the microbial community structure is warranted to optimize system performance. Full article

Flexible piezoelectric fibers are promising materials for next-generation wearable and flexible electronic devices due to their lightweight structure, mechanical flexibility, and electromechanical response. In this study, BaTiO₃/PVDF composite fibers were prepared by melt spinning under an electrostatic field, followed by thermal drawing to enhance the electroactive phase content. The effects of BaTiO₃ loading, draw ratio, thermal stretching ratio, stretching rate, and electric field strength on the crystalline structure of the fibers were systematically investigated. Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and electron microscopy were used to evaluate phase evolution, crystallinity, and filler distribution. The results showed that the processing conditions significantly influenced the transformation of PVDF from the α-phase to the electroactive β-phase. The optimized fibers were obtained at 1 wt.% BaTiO₃, a thermal stretching ratio of 5, a stretching rate of 40 mm/min, and an electric field strength of 18 kV, resulting in a crystallinity of 61.3% and a β-phase content of 95.5%. The enhanced structural characteristics indicate the strong potential of the developed composite fibers for flexible electroactive applications, though direct electromechanical characterization is required for device integration. Full article