Search Results (467)

Electrospun one-dimensional nanocomposites composed of polyvinylpyrrolidone (PVP) matrices reinforced with antimony sulphoiodide (SbSI) or antimony selenoiodide (SbSeI) nanowires were fabricated for the first time. Their properties were investigated for applications in piezoelectric sensors and nanogenerators. Precise control of the electrospinning parameters produced nanofibres with diameters comparable to the lateral dimensions of the nanowires, ensuring parallel alignment and a 1–3 composite structure. Structural analysis confirmed uniform nanowire distribution and stoichiometry retention. In both nanocomposites, the alignment of the nanowires enables clear observation of the anisotropy of their piezoelectric properties. PVP/SbSI nanocomposites exhibited a ferroelectric–paraelectric transition near 290 K. Under air-pressure excitation of 17.03 bar, they generated a maximum piezoelectric voltage of 2.09 V, with a sensitivity of 229 mV/bar and a surface power density of 12.0 µW/cm² for sandwich-type samples with nanowires aligned perpendicularly to the electrodes. PVP/SbSeI composites demonstrated stable semiconducting behaviour with a maximum piezoelectric voltage of 1.56 V, sensitivity of 130 mV/bar, and surface power density of 2.3 µW/cm² for the same type of sample and excitation. The high piezoelectric coefficients d₃₃ of 98 pC/N and 64 pC/N for PVP/SbSI and PVP/SbSeI, respectively, combined with mechanical flexibility, confirm the effectiveness of these nanocomposites as a practical solution for mechanical energy harvesting and pressure sensing in nanogenerators and sensors. Full article

Nickel oxide (NiO), a wide bandgap p-type semiconductor, has emerged as a promising material for electrochemical sensing owing to its excellent redox properties, chemical stability, and facile synthesis. Its strong electrocatalytic activity enables effective detection of diverse analytes, including glucose, hydrogen peroxide, environmental pollutants, and biomolecules. Advances in nanotechnology have enabled the development of NiO-based nanostructures such as nanoparticles, nanowires, and nanoflakes, which offer enhanced surface area and improved electron transfer. Integration with conductive materials like graphene, carbon nanotubes, and metal–organic frameworks (MOFs) further enhance sensor performance through synergistic effects. Innovations in synthesis techniques, including hydrothermal, sol–gel, and green approaches, have expanded the applicability of NiO in next-generation sensing platforms. This review summarizes recent progress in the structural engineering, composite formation, and electrochemical mechanisms of NiO-based materials for advanced electrochemical sensing applications. Full article

Indium oxide-based gas sensors have been proven to be a promising material for detecting nitrogen dioxide (NO₂) gas because of its wide bandgap and stability. In this paper, the enhancement mechanism for the sensitivity of indium oxide NO₂ gas sensors was systematically investigated using density functional theory (DFT) calculations and experimental validation with noble metals like Au, Ag, Pt, Pd, and Cu. We have fabricated a GaN nanowire-based NO₂ gas sensor functionalized with In₂O₃ and decorated with noble metals using a standard fabrication technique. Experimental tests showed that Au/In₂O₃ sensors exhibited the highest response of 38.9% followed by bare In₂O₃ with 10% for 10 ppm NO₂ at room temperature. The sensing properties were mainly attributed to a spillover effect or catalytic performance of Au with In₂O₃. The adsorption energies, charge transfers, and band gap confirm the enhanced sensing capability of Au-decorated Indium oxide for a NO₂ gas sensor. Full article

Optimal sensing devices exhibit a combination of key performance attributes, including an extensive detection limit, exceptional selectivity, high sensitivity, consistent repeatability, precise measurement, and rapid response times with efficient analyte flow. In recent years, biosensing platforms incorporating nanoscale materials have garnered considerable attention due to their diverse applications across various scientific and technological domains. The integration of nanoparticles (NPs) in biosensor design primarily bridges the dimensional gap between the signal transduction element and the biological recognition component, both of which operate at nanometer scales. The synergistic combination of NPs with electrochemical techniques has facilitated the development of biosensors characterized by enhanced sensitivity and superior analyte discrimination capabilities. This comprehensive analysis examines the evolution and recent advancements in nanomaterial (NM)-based biosensors, encompassing an extensive array of nanostructures. These consists of one-dimensional nanostructures including carbon nanotubes (CNTs), nanowires (NWs), nanorods (NRs), and quantum dots (QDs), as well as noble metal and metal and metal oxide nanoparticles (NPs). The article examines how advancements in biosensing techniques across a range of applications have been fueled by the growth of nanotechnology. Researchers have significantly improved biosensor performance parameters by utilizing the distinct physiochemical properties of these NMs. The developments have increased the potential uses of nanobiosensors in a wide range of fields, from food safety and biodefense to medical diagnostics and environmental monitoring. The continuous developments in NM-based biosensors are the result of the integration of several scientific areas, such as analytical chemistry, materials science, and biotechnology. This interdisciplinary approach continues to drive innovations in sensor design, signal amplification strategies, and data analysis techniques, ultimately leading to more sophisticated and capable biosensing platforms. As the field progresses, challenges related to the scalability, reproducibility, and long-term stability of nanobiosensors are being addressed through innovative fabrication methods and surface modification techniques. These efforts aim to translate the promising results observed in laboratory settings into practical, commercially viable biosensing devices that can address real-world analytical challenges across various sectors. Full article

Rapid on-site detection of chemical warfare agents (CWAs) is vital for security and environmental monitoring. In this work, copper(I) oxide (Cu₂O) nanowire (NW) chemiresistors were investigated as gas sensors for low-concentration organophosphorus chemical warfare agent (CWA) simulants. The NWs were hydrothermally synthesized and deposited onto microheater platforms, enabling them to operate at elevated working temperatures. Their sensing performance was tested against a range of vapor-phase simulants, including dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), diethyl ethylphosphonate (DEEP), diphenyl phosphoryl chloride (DPPCl), parathion, diethyl phosphite (DEP), diethyl adipate (DEA), and cyanogen chloride (ClCN). Fully oxidized P(V) simulants (DMMP, DEEP, TEP) produced modest, predominantly reversible responses (~3–6% RR). On the contrary, DPPCl and DEP induced the strongest relative responses (RR −94.67% and >200%, respectively), accompanied by irreversible surface modification as revealed by SEM and EDS. ClCN produced a substantial but reversible negative response (RR −9.5%), consistent with transient oxidative interactions. Surface poisoning was confirmed after exposure to DEP and DPPCl, which left phosphorus or chlorine residues on the Cu₂O surface. These results highlight both the promise and limitations of Cu₂O NW chemiresistors for selective CWA detection. Full article

To expand the application of silver nanowires (AgNWs) in the field of flexible sensors, this study developed a stretchable flexible sensor based on thermoplastic polyurethane (TPU). Initially, the TPU nanofiber membrane was prepared by electrospinning. Subsequently, high-aspect-ratio AgNWs were synthesized via a one-step polyol reduction method. The AgNWs with the optimal aspect ratio were selected for the conductive layer and spray-coated onto the surface of the TPU nanofiber membrane. Another layer of TPU nanofiber membrane was then laminated on top, resulting in a flexible thin-film sensor with a “sandwich” structure. Through morphological, chemical structure, and crystallinity analyses, the primary factors influencing AgNWs’ growth were investigated. Performance tests revealed that the prepared AgNWs had an average length of approximately 130 μm, a diameter of about 80 nm, and an average aspect ratio exceeding 1500, with the highest being 1921. The obtained sensor exhibited a low initial resistance (26.7 Ω), high strain range (sensing, ε = 0–150%), high sensitivity (GF, over 19.21), fast response and recovery time (112 ms), and excellent conductivity (428 S/cm). Additionally, the sensor maintained stable resistance after 3000 stretching cycles at a strain range of 0–10%. The sensor could output stable and recognizable electrical signals, demonstrating significant potential for applications in motion monitoring, human–computer interaction, and healthcare fields. Full article

This study reports the development of a highly sensitive electrochemical sensor for phosphate ion detection, utilizing silicon nanowires (SiNWs) as the transducing elements and a novel copper (II) phthalocyanine-acrylate polymer adduct (Cu (II) Pc-PAA) as the functional sensing layer. Silicon nanowires were fabricated via metal-assisted chemical etching (MACE) with etching durations of 15, 25, 35, 45, and 60 min. The SiNWs etched for 15 min exhibited the highest sensitivity, showing superior electrochemical performance. Functionalized SiNWs were systematically evaluated for phosphate ion (HPO₄²⁻) detection over a wide concentration range (10⁻¹⁰ to 10⁻⁶ M) using Mott–Schottky measurements. The surface morphology of the SiNWs was thoroughly characterized before and after Cu (II) Pc-PAA layer functionalization. The sensing material was analyzed using contact angle goniometry and scanning electron microscopy (SEM), confirming both its uniform distribution and effective immobilization. The sensor displayed a Nernstian behavior with a sensitivity of 28.25 mV/Decade and an exceptionally low limit of detection (LOD) of 1.5 nM. Furthermore, the capacitive sensor exhibited remarkable selectivity toward phosphate ions, even in the presence of potentially interfering anions such as Cl⁻, NO₃⁻, SO₄²⁻ and ClO₄⁻. These results confirm the sensor’s high sensitivity, selectivity, and fast response, underscoring its suitability for environmental phosphate ion monitoring. Full article

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

Efficient detection of toxic and flammable vapors remains a major technological challenge, especially for environmental and industrial applications. This paper reports on the fabrication technology and gas-sensing properties of nanostructured Ga₂O₃/GaS_0.98Se_0.02. The β-Ga₂O₃ nanowires/nanoribbons with inclusions of Ga₂S₃ and Ga₂Se₃ microcrystallites were obtained by thermal treatment of GaS_0.98Se_0.02 slabs in air enriched with water vapors. The microstructure, crystalline quality, and elemental composition of the obtained samples were investigated using electron microscopy, X-ray diffraction, and Raman spectroscopy. The obtained structures show promising results as active elements in gas sensor applications. Vapors of methanol (CH₃OH), ethanol (C₂H₅OH), and acetone (CH₃-CO-CH₃) were successfully detected using the nanostructured samples. The electrical signal for gas detection was enhanced under UV light irradiation. The saturation time of the sensor depends on the intensity of the UV radiation beam. Full article

This study presents the development of a TiO₂ nanowire-based electrochemical sensor for the selective and sensitive detection of hydrogen peroxide (H₂O₂) under neutral pH conditions, with a particular focus on its application in analyzing plant stress. The sensor exhibited a linear detection range of 0–0.5 mM, a sensitivity of 0.0393 mA · mM⁻¹, and a detection limit of 2.8 μM in phosphate-buffered saline solution (PBS, pH 7.4). This work’s main novelty lies in the systematic investigation of the relationship between TiO₂ nanostructure morphology, which is controlled by hydrothermal synthesis parameters, and the resulting sensor performance. Interference studies confirmed excellent selectivity in the presence of common electroactive species found in plant samples, such as NaCl, KNO₃, glucose, citric acid, and ascorbic acid. Real sample analysis using barley plant extracts grown under salt stress and treated with Fe₃O₄ nanoparticles confirmed the sensor’s applicability in complex biological matrices, enabling accurate quantification of endogenously produced H₂O₂. Endogenous H₂O₂ concentrations were found to range from near-zero levels in control and Fe₃O₄-only treated plants, to elevated levels of up to 0.36 mM in salt-stressed samples. These levels decreased to 0.25 and 0.15 mM upon Fe₃O₄ nanoparticle treatment, indicating a dose-dependent mitigation of stress. This finding was supported by genome template stability (GTS) analysis, which revealed improved DNA integrity in Fe₃O₄-treated plants. This study takes an integrated approach, combining the development of a nanostructured sensor with physiological and molecular stress assessment. The urgent need for tools to detect stress at an early stage and manage oxidative stress in sustainable agriculture underscores its relevance. Full article

A facile fabrication method was developed for the growth of Cu_1.8Se nanosheets (NSs) on a Cu foil substrate, enabling dual-functionality as an electrochemical sensor for H₂O₂ and an active surface-enhanced Raman scattering (SERS) substrate. The process involved the preparation of Cu(OH)₂ nanowires (NWs) via electrochemical oxidation, followed by chemical conversion to Cu_1.8Se through a selenization process. The morphology, composition, and microstructure of the resulting Cu_1.8Se NSs were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The Cu_1.8Se NSs exhibited excellent electrocatalytic activity for H₂O₂ reduction, achieving a notably low detection limit of 1.25 μM and demonstrating rapid response and high sensitivity with a linear relationship in amperometric detection. Additionally, SERS experiments using Rhodamine B as a probe molecule and the Cu_1.8Se NS/Cu foil as a substrate displayed outstanding performance, with a detection limit as low as 1 μM. The flower-like structure of the Cu_1.8Se NSs exhibited linear dependence between analyte concentration and detection signals, along with satisfactory reproducibility in dual-sensing applications. These findings underscore the scalability and potential of this fabrication approach for advanced sensor development. Full article

Resistive gas sensors have attracted significant attention due to their simple architecture, low cost, and ease of integration, with widespread applications in environmental monitoring, industrial safety, and healthcare diagnostics. This review provides a comprehensive overview of recent advances in resistive gas sensors, focusing on their fundamental working mechanisms, sensing material design, device architecture optimization, and intelligent system integration. These sensors primarily operate based on changes in electrical resistance induced by interactions between gas molecules and sensing materials, including physical adsorption, charge transfer, and surface redox reactions. In terms of materials, metal oxide semiconductors, conductive polymers, carbon-based nanomaterials, and their composites have demonstrated enhanced sensitivity and selectivity through strategies such as doping, surface functionalization, and heterojunction engineering, while also enabling reduced operating temperatures. Device-level innovations—such as microheater integration, self-heated nanowires, and multi-sensor arrays—have further improved response speed and energy efficiency. Moreover, the incorporation of artificial intelligence (AI) and Internet of Things (IoT) technologies has significantly advanced signal processing, pattern recognition, and long-term operational stability. Machine learning (ML) algorithms have enabled intelligent design of novel sensing materials, optimized multi-gas identification, and enhanced data reliability in complex environments. These synergistic developments are driving resistive gas sensors toward low-power, highly integrated, and multifunctional platforms, particularly in emerging applications such as wearable electronics, breath diagnostics, and smart city infrastructure. This review concludes with a perspective on future research directions, emphasizing the importance of improving material stability, interference resistance, standardized fabrication, and intelligent system integration for large-scale practical deployment. Full article

Seafood, especially marine fish, is highly prone to spoilage during processing, transportation, and storage. It releases pungent trimethylamine (TMA) gas, which severely affects food quality and safety. Metal–oxide–semiconductor (MOS) gas sensors for TMA detection offer a rapid, convenient, and accurate method for assessing fish freshness. Indium oxide (In₂O₃) has shown potential as an effective sensing material for the detection of TMA. In this work, one-dimensional In₂O₃ nanowires with different grain sizes and levels of crystallinity were synthetized using the electrospinning technique and underwent different thermal calcination processes. Gas-sensing tests showed that the In₂O₃–3 °C/min–500 °C gas sensor exhibited an outstanding performance, including a high response (R_a/R_g = 47.0) to 100 ppm TMA, a short response time (6 s), a low limit of detection (LOD, 0.0392 ppm), and an excellent long-term stability. Furthermore, the sensor showed promising experimental results in monitoring the freshness of Larimichthys crocea (L. crocea). By analyzing the relationship between the grain size and crystallinity of the In₂O₃ samples, a mechanism for the enhanced gas-sensing performance was proposed. This work provides a novel strategy for designing and fabricating gas sensors for TMA detection and highlights their potential for broad applications in real-time fish freshness monitoring. Full article

Hexagonal ZnO nanowires were grown using the PLD/VLS technique on a SAW sensor active area for hydrogen sensing. The influence of different carbon and nitrogen surface contaminant concentrations on sensor output was investigated for three active area cases: a few weeks’ exposure to free ambient air contamination, 3 h at 600 °C thermal desorption of carbon, and (room temperature) plasma-activated nitrogen and carbon contamination. Correlations between sensing performance and contamination element concentration were established. To understand the adsorption versus absorption mechanisms, similar studies were further performed on circular ZnO nanowires morphology, which have a different surface-area-to-volume ratio. Comparative results show that, while a 20% carbon surface contamination variation generates a variation of 3–5% in nanostructure hydrogen sorption, nitrogen surface contamination influence depends on nanostructure morphology. Thus, in our comparative studies, for the case of a nanowire hexagonal cross-section a 12% nitrogen surface contamination variation generates a 5–7% increase in hydrogen adsorption and also an increase of 6–8% in hydrogen absorption. Consequently, the catalytic effect of nitrogen could enlarge the linear response of nanowire-based (SAW) sensors over a wider hydrogen concentration range. 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