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Search Results (1,444)

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Keywords = Thin-film sensor

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15 pages, 796 KiB  
Article
Electroassisted Incorporation of Ferrocene Within Sol–Gel Silica Films to Enhance Electron Transfer—Part II: Boosting Protein Sensing with Polyelectrolyte-Modified Silica
by Rayane-Ichrak Loughlani, Alonso Gamero-Quijano and Francisco Montilla
Molecules 2025, 30(15), 3246; https://doi.org/10.3390/molecules30153246 - 2 Aug 2025
Viewed by 153
Abstract
Silica-modified electrodes possess physicochemical properties that make them valuable in electrochemical sensing and energy-related applications. Although intrinsically insulating, silica thin films can selectively interact with redox species, producing sieving effects that enhance electrochemical responses. We synthesized Class I hybrid silica matrices incorporating either [...] Read more.
Silica-modified electrodes possess physicochemical properties that make them valuable in electrochemical sensing and energy-related applications. Although intrinsically insulating, silica thin films can selectively interact with redox species, producing sieving effects that enhance electrochemical responses. We synthesized Class I hybrid silica matrices incorporating either negatively charged poly(4-styrene sulfonic acid) or positively charged poly(diallyl dimethylammonium chloride). These hybrid films were deposited onto ITO electrodes and evaluated via cyclic voltammetry in aqueous ferrocenium solutions. The polyelectrolyte charge played a key role in the electroassisted incorporation of ferrocene: silica-PSS films promoted accumulation, while silica-PDADMAC films hindered it due to electrostatic repulsion. In situ UV-vis spectroscopy confirmed that only a fraction of the embedded ferrocene was electroactive. Nevertheless, this fraction enabled effective mediated detection of cytochrome c in solution. These findings highlight the crucial role of ionic interactions and hybrid composition in electron transfer to redox proteins, providing valuable insights for the development of advanced bioelectronic sensors. Full article
(This article belongs to the Section Electrochemistry)
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37 pages, 5131 KiB  
Review
Coating Metal–Organic Frameworks (MOFs) and Associated Composites on Electrodes, Thin Film Polymeric Materials, and Glass Surfaces
by Md Zahidul Hasan, Tyeaba Tasnim Dipti, Liu Liu, Caixia Wan, Li Feng and Zhongyu Yang
Nanomaterials 2025, 15(15), 1187; https://doi.org/10.3390/nano15151187 - 2 Aug 2025
Viewed by 262
Abstract
Metal–Organic Frameworks (MOFs) have emerged as advanced porous crystalline materials due to their highly ordered structures, ultra-high surface areas, fine-tunable pore sizes, and massive chemical diversity. These features, arising from the coordination between an almost unlimited number of metal ions/clusters and organic linkers, [...] Read more.
Metal–Organic Frameworks (MOFs) have emerged as advanced porous crystalline materials due to their highly ordered structures, ultra-high surface areas, fine-tunable pore sizes, and massive chemical diversity. These features, arising from the coordination between an almost unlimited number of metal ions/clusters and organic linkers, have resulted in significant interest in MOFs for applications in gas storage, catalysis, sensing, energy, and biomedicine. Beyond their stand-alone properties and applications, recent research has increasingly explored the integration of MOFs with other substrates, particularly electrodes, polymeric thin films, and glass surfaces, to create synergistic effects that enhance material performance and broaden application potential. Coating MOFs onto these substrates can yield significant benefits, including, but not limited to, improved sensitivity and selectivity in electrochemical sensors, enhanced mechanical and separation properties in membranes, and multifunctional coatings for optical and environmental applications. This review provides a comprehensive and up-to-date summary of recent advances (primarily from the past 3–5 years) in MOF coating techniques, including layer-by-layer assembly, in situ growth, and electrochemical deposition. This is followed by a discussion of the representative applications arising from MOF-substrate coating and an outline of key challenges and future directions in this rapidly evolving field. This article aims to serve as a focused reference point for researchers interested in both fundamental strategies and applied developments in MOF surface coatings. Full article
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13 pages, 1717 KiB  
Article
High-Performance Hydrogen Gas Sensor Based on Pd-Doped MoS2/Si Heterojunction
by Enyu Ma, Zihao Xu, Ankai Sun, Shuo Yang and Jianyu Jiang
Sensors 2025, 25(15), 4753; https://doi.org/10.3390/s25154753 - 1 Aug 2025
Viewed by 186
Abstract
High-performance hydrogen gas sensors have gained considerable interest for their crucial function in reducing H2 explosion risk. Although MoS2 has good potential for chemical sensing, its application in hydrogen detection at room temperature is limited by slow response and incomplete recovery. [...] Read more.
High-performance hydrogen gas sensors have gained considerable interest for their crucial function in reducing H2 explosion risk. Although MoS2 has good potential for chemical sensing, its application in hydrogen detection at room temperature is limited by slow response and incomplete recovery. In this work, Pd-doped MoS2 thin films are deposited on a Si substrate, forming Pd-doped MoS2/Si heterojunctions via magnetron co-sputtering. The incorporation of Pd nanoparticles significantly enhances the catalytic activity for hydrogen adsorption and facilitates more efficient electron transfer. Owing to its distinct structural characteristics and sharp interface properties, the fabricated Pd-doped MoS2/Si heterojunction device exhibits excellent H2 sensing performance under room temperature conditions. The gas sensor device achieves an impressive sensing response of ~6.4 × 103% under 10,000 ppm H2 concentration, representing a 110% improvement compared to pristine MoS2. Furthermore, the fabricated heterojunction device demonstrates rapid response and recovery times (24.6/12.2 s), excellent repeatability, strong humidity resistance, and a ppb-level detection limit. These results demonstrate the promising application prospects of Pd-doped MoS2/Si heterojunctions in the development of advanced gas sensing devices. Full article
(This article belongs to the Special Issue 2D Materials for Advanced Sensing Technology)
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29 pages, 14906 KiB  
Article
Hydrothermal Engineering of Ferroelectric PZT Thin Films Tailoring Electrical and Ferroelectric Properties via TiO2 and SrTiO3 Interlayers for Advanced MEMS
by Chun-Lin Li and Guo-Hua Feng
Micromachines 2025, 16(8), 879; https://doi.org/10.3390/mi16080879 - 29 Jul 2025
Viewed by 207
Abstract
This work presents an innovative hydrothermal approach for fabricating flexible piezoelectric PZT thin films on 20 μm titanium foil substrates using TiO2 and SrTiO3 (STO) interlayers. Three heterostructures (Ti/PZT, Ti/TiO2/PZT, and Ti/TiO2/STO/PZT) were synthesized to enable low-temperature [...] Read more.
This work presents an innovative hydrothermal approach for fabricating flexible piezoelectric PZT thin films on 20 μm titanium foil substrates using TiO2 and SrTiO3 (STO) interlayers. Three heterostructures (Ti/PZT, Ti/TiO2/PZT, and Ti/TiO2/STO/PZT) were synthesized to enable low-temperature growth and improve ferroelectric performance for advanced flexible MEMS. Characterizations including XRD, PFM, and P–E loop analysis evaluated crystallinity, piezoelectric coefficient d33, and polarization behavior. The results demonstrate that the multilayered Ti/TiO2/STO/PZT structure significantly enhances performance. XRD confirmed the STO buffer layer effectively reduces lattice mismatch with PZT to ~0.76%, promoting stable morphotropic phase boundary (MPB) composition formation. This optimized film exhibited superior piezoelectric and ferroelectric properties, with a high d33 of 113.42 pm/V, representing an ~8.65% increase over unbuffered Ti/PZT samples, and displayed more uniform domain behavior in PFM imaging. Impedance spectroscopy showed the lowest minimum impedance of 8.96 Ω at 10.19 MHz, indicating strong electromechanical coupling. Furthermore, I–V measurements demonstrated significantly suppressed leakage currents in the STO-buffered samples, with current levels ranging from 10−12 A to 10−9 A over ±3 V. This structure also showed excellent fatigue endurance through one million electrical cycles, confirming its mechanical and electrical stability. These findings highlight the potential of this hydrothermally engineered flexible heterostructure for high-performance actuators and sensors in advanced MEMS applications. Full article
(This article belongs to the Special Issue Manufacturing and Application of Advanced Thin-Film-Based Device)
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23 pages, 3210 KiB  
Article
Design and Optimization of Intelligent High-Altitude Operation Safety System Based on Sensor Fusion
by Bohan Liu, Tao Gong, Tianhua Lei, Yuxin Zhu, Yijun Huang, Kai Tang and Qingsong Zhou
Sensors 2025, 25(15), 4626; https://doi.org/10.3390/s25154626 - 25 Jul 2025
Viewed by 234
Abstract
In the field of high-altitude operations, the frequent occurrence of fall accidents is usually closely related to safety measures such as the incorrect use of safety locks and the wrong installation of safety belts. At present, the manual inspection method cannot achieve real-time [...] Read more.
In the field of high-altitude operations, the frequent occurrence of fall accidents is usually closely related to safety measures such as the incorrect use of safety locks and the wrong installation of safety belts. At present, the manual inspection method cannot achieve real-time monitoring of the safety status of the operators and is prone to serious consequences due to human negligence. This paper designs a new type of high-altitude operation safety device based on the STM32F103 microcontroller. This device integrates ultra-wideband (UWB) ranging technology, thin-film piezoresistive stress sensors, Beidou positioning, intelligent voice alarm, and intelligent safety lock. By fusing five modes, it realizes the functions of safety status detection and precise positioning. It can provide precise geographical coordinate positioning and vertical ground distance for the workers, ensuring the safety and standardization of the operation process. This safety device adopts multi-modal fusion high-altitude operation safety monitoring technology. The UWB module adopts a bidirectional ranging algorithm to achieve centimeter-level ranging accuracy. It can accurately determine dangerous heights of 2 m or more even in non-line-of-sight environments. The vertical ranging upper limit can reach 50 m, which can meet the maintenance height requirements of most transmission and distribution line towers. It uses a silicon carbide MEMS piezoresistive sensor innovatively, which is sensitive to stress detection and resistant to high temperatures and radiation. It builds a Beidou and Bluetooth cooperative positioning system, which can achieve centimeter-level positioning accuracy and an identification accuracy rate of over 99%. It can maintain meter-level positioning accuracy of geographical coordinates in complex environments. The development of this safety device can build a comprehensive and intelligent safety protection barrier for workers engaged in high-altitude operations. Full article
(This article belongs to the Section Electronic Sensors)
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20 pages, 1471 KiB  
Article
A New Approach for Interferent-Free Amperometric Biosensor Production Based on All-Electrochemically Assisted Procedures
by Rosanna Ciriello, Maria Assunta Acquavia, Giuliana Bianco, Angela Di Capua and Antonio Guerrieri
Biosensors 2025, 15(8), 470; https://doi.org/10.3390/bios15080470 - 22 Jul 2025
Viewed by 295
Abstract
A new approach in amperometric enzyme electrodes production based on all-electrochemically assisted procedures will be described. Enzyme (glucose oxidase) immobilization was performed by in situ co-crosslinking of enzyme molecules through electrophoretic protein deposition, assuring enzyme immobilization exclusively onto the transducer surface (Pt electrode). [...] Read more.
A new approach in amperometric enzyme electrodes production based on all-electrochemically assisted procedures will be described. Enzyme (glucose oxidase) immobilization was performed by in situ co-crosslinking of enzyme molecules through electrophoretic protein deposition, assuring enzyme immobilization exclusively onto the transducer surface (Pt electrode). Analogously, the poor selectivity of the transducer was dramatically improved by the electrosynthesis of non-conducting polymers with built-in permselectivity, permitting the formation of a thin permselective film onto the transducer surface, able to reject common interferents usually found in real samples. Since both approaches required a proper and distinct electrochemical perturbation (a pulsed current sequence for electrophoretic protein deposition and cyclic voltammetry for the electrosynthesis of non-conducting polymers), an appropriate coupling of the two all-electrochemical approaches was assured by a thorough study of the likely combinations of the electrosynthesis of permselective polymers with enzyme immobilization by electrophoretic protein deposition and by the use of several electrosynthesized polymers. For each investigated combination and for each polymer, the analytical performances and the rejection capabilities of the resulting biosensor were acquired so to gain information about their sensing abilities eventually in real sample analysis. This study shows that the proper coupling of the two all-electrochemical approaches and the appropriate choice of the electrosynthesized, permselective polymer permits the easy fabrication of novel glucose oxidase biosensors with good analytical performance and low bias in glucose measurement from typical interferent in serum. This novel approach, resembling classical electroplating procedures, is expected to allow all the advantages expected from such procedures like an easy preparation biosensor, a bi-dimensional control of enzyme immobilization and thickness, interferent- and fouling-free transduction of the electrodic sensor and, last but not the least, possibility of miniaturization of the biosensing device. Full article
(This article belongs to the Special Issue Novel Designs and Applications for Electrochemical Biosensors)
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81 pages, 10454 KiB  
Review
Glancing Angle Deposition in Gas Sensing: Bridging Morphological Innovations and Sensor Performances
by Shivam Singh, Kenneth Christopher Stiwinter, Jitendra Pratap Singh and Yiping Zhao
Nanomaterials 2025, 15(14), 1136; https://doi.org/10.3390/nano15141136 - 21 Jul 2025
Viewed by 365
Abstract
Glancing Angle Deposition (GLAD) has emerged as a versatile and powerful nanofabrication technique for developing next-generation gas sensors by enabling precise control over nanostructure geometry, porosity, and material composition. Through dynamic substrate tilting and rotation, GLAD facilitates the fabrication of highly porous, anisotropic [...] Read more.
Glancing Angle Deposition (GLAD) has emerged as a versatile and powerful nanofabrication technique for developing next-generation gas sensors by enabling precise control over nanostructure geometry, porosity, and material composition. Through dynamic substrate tilting and rotation, GLAD facilitates the fabrication of highly porous, anisotropic nanostructures, such as aligned, tilted, zigzag, helical, and multilayered nanorods, with tunable surface area and diffusion pathways optimized for gas detection. This review provides a comprehensive synthesis of recent advances in GLAD-based gas sensor design, focusing on how structural engineering and material integration converge to enhance sensor performance. Key materials strategies include the construction of heterojunctions and core–shell architectures, controlled doping, and nanoparticle decoration using noble metals or metal oxides to amplify charge transfer, catalytic activity, and redox responsiveness. GLAD-fabricated nanostructures have been effectively deployed across multiple gas sensing modalities, including resistive, capacitive, piezoelectric, and optical platforms, where their high aspect ratios, tailored porosity, and defect-rich surfaces facilitate enhanced gas adsorption kinetics and efficient signal transduction. These devices exhibit high sensitivity and selectivity toward a range of analytes, including NO2, CO, H2S, and volatile organic compounds (VOCs), with detection limits often reaching the parts-per-billion level. Emerging innovations, such as photo-assisted sensing and integration with artificial intelligence for data analysis and pattern recognition, further extend the capabilities of GLAD-based systems for multifunctional, real-time, and adaptive sensing. Finally, current challenges and future research directions are discussed, emphasizing the promise of GLAD as a scalable platform for next-generation gas sensing technologies. Full article
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16 pages, 10306 KiB  
Article
Fabrication and Characterization of Flexible pH Sensors Based on Pulsed Laser-Ablated Graphene/MoS2 Interdigitated Electrodes
by Zhaochi Chen, Chengche Liu and Minh-Quang Tran
Nanomaterials 2025, 15(14), 1115; https://doi.org/10.3390/nano15141115 - 18 Jul 2025
Viewed by 407
Abstract
Point-of-care (POC) diagnostic technologies have become essential for the real-time monitoring and management of chronic wounds, where maintaining a moist environment and controlling pH levels are critical for effective healing. In this study, a flexible pH sensor based on a graphene/molybdenum disulfide (graphene/MoS [...] Read more.
Point-of-care (POC) diagnostic technologies have become essential for the real-time monitoring and management of chronic wounds, where maintaining a moist environment and controlling pH levels are critical for effective healing. In this study, a flexible pH sensor based on a graphene/molybdenum disulfide (graphene/MoS2) composite interdigitated electrode (IDE) structure was fabricated using pulsed laser ablation. The pH sensor, with an active area of 30 mm × 30 mm, exhibited good adhesion to the polyethylene terephthalate (PET) substrate and maintained structural integrity under repeated bending cycles. Precise ablation was achieved under optimized conditions of 4.35 J/cm2 laser fluence, a repetition rate of 300 kHz, and a scanning speed of 500 mm/s, enabling the formation of defect-free IDE arrays without substrate damage. The influence of laser processing parameters on the surface morphology, electrical conductivity, and wettability of the composite thin films was systematically characterized. The fabricated pH sensor exhibited high sensitivity (~4.7% change in current per pH unit) across the pH 2–10 range, rapid response within ~5.2 s, and excellent mechanical stability under 100 bending cycles with negligible performance degradation. Moreover, the sensor retained > 95% of its stable sensitivity after 7 days of ambient storage. Furthermore, the pH response behavior was evaluated for electrode structures with different pitches, demonstrating that structural design parameters critically impact sensing performance. These results offer valuable insights into the scalable fabrication of flexible, wearable pH sensors, with promising applications in wound monitoring and personalized healthcare systems. Full article
(This article belongs to the Special Issue Laser-Based Nano Fabrication and Nano Lithography: Second Edition)
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21 pages, 9529 KiB  
Article
Development of a Highly Reliable PbS QDs-Based SWIR Photodetector Based on Metal Oxide Electron/Hole Extraction Layer Formation Conditions
by JinBeom Kwon, Yuntae Ha, Suji Choi and Donggeon Jung
Nanomaterials 2025, 15(14), 1107; https://doi.org/10.3390/nano15141107 - 16 Jul 2025
Viewed by 294
Abstract
Recently, with the development of automation technology in various fields, much research has been conducted on infrared photodetectors, which are the core technology of LiDAR sensors. However, most infrared photodetectors are expensive because they use compound semiconductors based on epitaxial processes, and they [...] Read more.
Recently, with the development of automation technology in various fields, much research has been conducted on infrared photodetectors, which are the core technology of LiDAR sensors. However, most infrared photodetectors are expensive because they use compound semiconductors based on epitaxial processes, and they have low safety because they use the near-infrared (NIR) region that can damage the retina. Therefore, they are difficult to apply to automation technologies such as automobiles and factories where humans can be constantly exposed. In contrast, short-wavelength infrared photodetectors based on PbS QDs are actively being developed because they can absorb infrared rays in the eye-safe region by controlling the particle size of QDs and can be easily and inexpensively manufactured through a solution process. However, PbS QDs-based SWIR photodetectors have low chemical stability due to the electron/hole extraction layer processed by the solution process, making it difficult to manufacture them in the form of patterning and arrays. In this study, bulk NiO and ZnO were deposited by sputtering to achieve uniformity and patterning of thin films, and the performance of PbS QDs-based photodetectors was improved by optimizing the thickness and annealing conditions of the thin films. The fabricated photodetector achieved a high response characteristic of 114.3% through optimized band gap and improved transmittance characteristics. Full article
(This article belongs to the Special Issue Quantum Dot Materials and Their Optoelectronic Applications)
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13 pages, 4656 KiB  
Article
High-Speed and Hysteresis-Free Near-Infrared Optical Hydrogen Sensor Based on Ti/Pd Bilayer Thin Films
by Ashwin Thapa Magar, Tu Anh Ngo, Hoang Mai Luong, Thi Thu Trinh Phan, Minh Tuan Trinh, Yiping Zhao and Tho Duc Nguyen
Nanomaterials 2025, 15(14), 1105; https://doi.org/10.3390/nano15141105 - 16 Jul 2025
Viewed by 496
Abstract
Palladium (Pd) and titanium (Ti) exhibit opposite dielectric responses upon hydrogenation, with stronger effects observed in the near-infrared (NIR) region. Leveraging this contrast, we investigated Ti/Pd bilayer thin films as a platform for NIR hydrogen sensing—particularly at telecommunication-relevant wavelengths, where such devices have [...] Read more.
Palladium (Pd) and titanium (Ti) exhibit opposite dielectric responses upon hydrogenation, with stronger effects observed in the near-infrared (NIR) region. Leveraging this contrast, we investigated Ti/Pd bilayer thin films as a platform for NIR hydrogen sensing—particularly at telecommunication-relevant wavelengths, where such devices have remained largely unexplored. Ti/Pd bilayers coated with Teflon AF (TAF) and fabricated via sequential electron-beam and thermal evaporation were characterized using optical transmission measurements under repeated hydrogenation cycles. The Ti (5 nm)/Pd (x = 2.5 nm)/TAF (30 nm) architecture showed a 2.7-fold enhancement in the hydrogen-induced optical contrast at 1550 nm compared to Pd/TAF reference films, attributed to the hydrogen ion exchange between the Ti and Pd layers. The optimized structure, with a Pd thickness of x = 1.9 nm, exhibited hysteresis-free sensing behavior, a rapid response time (t90 < 0.35 s at 4% H2), and a detection limit below 10 ppm. It also demonstrated excellent selectivity with negligible cross-sensitivity to CO2, CH4, and CO, as well as high durability, showing less than 6% signal degradation over 135 hydrogenation cycles. These findings establish a scalable, room-temperature NIR hydrogen sensing platform with strong potential for deployment in automotive, environmental, and industrial applications. Full article
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15 pages, 2463 KiB  
Article
Measurement of the Effective Refractive Index of Suspensions Containing 5 µm Diameter Spherical Polystyrene Microparticles by Surface Plasmon Resonance and Scattering
by Osvaldo Rodríguez-Quiroz, Donato Luna-Moreno, Araceli Sánchez-Álvarez, Gabriela Elizabeth Quintanilla-Villanueva, Oscar Javier Silva-Hernández, Melissa Marlene Rodríguez-Delgado and Juan Francisco Villarreal-Chiu
Chemosensors 2025, 13(7), 257; https://doi.org/10.3390/chemosensors13070257 - 15 Jul 2025
Viewed by 347
Abstract
Microplastics (MP) have been found not only in the environment but also in living beings, including humans. As an initial step in MP detection, a method is proposed to measure the effective refractive index of a solution containing 5 µm diameter spherical polystyrene [...] Read more.
Microplastics (MP) have been found not only in the environment but also in living beings, including humans. As an initial step in MP detection, a method is proposed to measure the effective refractive index of a solution containing 5 µm diameter spherical polystyrene particles (SPSP) in distilled water, based on the surface plasmon resonance (SPR) technique and Mie scattering theory. The reflectances of the samples are obtained with their resonance angles and depths that must be normalized and adjusted according to the reference of the air and the distilled water, to subsequently find their effective refraction index corresponding to the Mie scattering theory. The system has an optical sensor with a Kretschmann–Raether configuration, consisting of a semicircular prism, a thin gold film, and a glass cell for solution samples with different concentrations (0.00, 0.20, 0.05, 0.50, and 1.00%). The experimental result provided a good linear fit with an R2 = 0.9856 and a sensitivity of 7.2863 × 105 RIU/% (refractive index unit per percentage of fill fraction). The limits of detection (LOD) and limit of quantification (LOQ) were determined to be 0.001% and 0.0035%, respectively. The developed optomechatronic system and its applications based on the SPR and Scattering enabled the effective measurement of the refractive index and concentration of solutions containing 5 µm diameter SPSP in distilled water. Full article
(This article belongs to the Special Issue Spectroscopic Techniques for Chemical Analysis)
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16 pages, 2441 KiB  
Article
Phosphonium Salt-Functionalized β-Cyclodextrin Film for Ultrasensitive and Selective Electrochemical Impedance Spectroscopy Detection of Perchlorate in Drinking Water
by Zeineb Baatout, Achref Jebnouni, Nawfel Sakly, Safa Teka, Nuzaiha Mohamed, Sayda Osman, Raoudha Soury, Mabrouka El Oudi, Salman Hamdan Alsaqri, Nejmeddine Smida Jaballah and Mustapha Majdoub
Polymers 2025, 17(14), 1937; https://doi.org/10.3390/polym17141937 - 15 Jul 2025
Viewed by 396
Abstract
This work represents the first use of a phosphonium salt-functionalized β-Cyclodextrin polymer (β-CDP) as a highly selective sensing membrane for monitoring the safety of drinking water against perchlorate ions (ClO4) using electrochemical impedance spectroscopy (EIS). Structural confirmation via 1H [...] Read more.
This work represents the first use of a phosphonium salt-functionalized β-Cyclodextrin polymer (β-CDP) as a highly selective sensing membrane for monitoring the safety of drinking water against perchlorate ions (ClO4) using electrochemical impedance spectroscopy (EIS). Structural confirmation via 1H NMR, 13C NMR, 31P NMR, and FT-IR spectroscopies combined with AFM and contact angle measurements demonstrate how the enhanced solubility of modified cyclodextrin improves thin film quality. The innovation lies in the synergistic combination of two detection mechanisms: the “Host-Guest” inclusion in the cyclodextrin cavity and anionic exchange between the bromide ions of the phosphonium groups and perchlorate anions. Under optimized functionalization conditions, EIS reveals high sensitivity and selectivity, achieving a record-low detection limit (LOD) of ~10−12 M and a wide linear range of detection (10−11 M–10−4 M). Sensing mechanisms at the functionalized transducer interfaces are examined through numerical fitting of Cole-Cole impedance spectra via a single relaxation equivalent circuit. Real water sample analysis confirms the sensor’s practical applicability, with recoveries between 96.9% and 109.8% and RSDs of 2.4–4.8%. Finally, a comparative study with reported membrane sensors shows that β-CDP offers superior performance, wider range, higher sensitivity, lower LOD, and simpler synthesis. Full article
(This article belongs to the Special Issue Development of Polymer Materials as Functional Coatings)
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11 pages, 1778 KiB  
Communication
Ultra-Sensitive Detection of Chloramphenicol by CdS@NiMoS Nanorods-Based Photoelectrochemical Aptasensor
by Hebin Sun, Yimeng Sun, Tong Qi, Zhenyu Wang, Jianlong Zhao and Lijuan Liang
Biosensors 2025, 15(7), 454; https://doi.org/10.3390/bios15070454 - 14 Jul 2025
Viewed by 368
Abstract
A novel nanomaterial photoelectrochemical aptamer sensor based on CdS@NiMoS heterojunction nanocomposites was constructed for highly sensitive detection of chloramphenicol (CAP) in antibiotic residues. Through optimization of the material synthesis process, the optimal doping ratio of MoS2 to Ni3+ (70% MoS2 [...] Read more.
A novel nanomaterial photoelectrochemical aptamer sensor based on CdS@NiMoS heterojunction nanocomposites was constructed for highly sensitive detection of chloramphenicol (CAP) in antibiotic residues. Through optimization of the material synthesis process, the optimal doping ratio of MoS2 to Ni3+ (70% MoS2 and 10% Ni3+) was identified, which significantly enhanced the photogenerated carrier separation efficiency. In thin-film preparation, comparative analysis of four film-forming methods led to the determination of an optimal process with stability. To achieve highly specific CAP detection, the nanocomposite chip was integrated with nucleic acid aptamer biorecognition elements within a standard three-electrode detection system. Experimental results demonstrated a linear response (R2 = 0.998) in the 0.1–2 μM concentration range, with a detection limit of 3.69 nM (3σ/S). Full article
(This article belongs to the Special Issue Nanotechnology Biosensing in Bioanalysis and Beyond)
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22 pages, 13907 KiB  
Article
Fabrication and Characterization of a Thermal Flow Sensor Based on the Ensinger Microsystems Technology
by Daniela Walter, André Bülau, Sebastian Bengsch, Kerstin Gläser and André Zimmermann
Metrology 2025, 5(3), 41; https://doi.org/10.3390/metrology5030041 - 3 Jul 2025
Viewed by 235
Abstract
Thermal mass flow sensors (TMFS) are used to detect the flow rates of gases. TMFS elements are available in different technologies and, depending on the one used, the material choice of substrate, heater, and temperature sensors can limit their performance. In this work, [...] Read more.
Thermal mass flow sensors (TMFS) are used to detect the flow rates of gases. TMFS elements are available in different technologies and, depending on the one used, the material choice of substrate, heater, and temperature sensors can limit their performance. In this work, a sensor element based on the Ensinger Microsystems Technology (EMST) is presented that uses PEEK as the substrate, nickel-chromium as the heater, and nickel as the temperature sensor material. The fabrication process of the element is described, the completion to a flow sensor with a control and readout circuit based on discharge time measurement with picosecond resolution is presented, and measurement results are shown, which are compared to sensors with a commercially available element based on thin film technology on ceramic and an element built with discrete components, all using the same electronics. It is shown that the operation of all sensor elements with the proposed readout circuit was successful, flow-dependent signals were achieved, and the performance of TMFS in EMST improved. Its heater shows better results compared to the commercial element due to material choice with a smaller temperature coefficient of resistance. In its current state, the TMFS in EMST is suitable to detect flow rates > 20 SLPM. The performance needs to be improved further, since the temperature sensors still differ too much from another. Full article
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11 pages, 2689 KiB  
Article
Growth of Zn–N Co-Doped Ga2O3 Films by a New Scheme with Enhanced Optical Properties
by Daogui Liao, Yijun Zhang, Ruikang Wang, Tianyi Yan, Chao Li, He Tian, Hong Wang, Zuo-Guang Ye, Wei Ren and Gang Niu
Nanomaterials 2025, 15(13), 1020; https://doi.org/10.3390/nano15131020 - 1 Jul 2025
Viewed by 376
Abstract
Gallium oxide (Ga2O3), as a wide-bandgap semiconductor material, is highly expected to find extensive applications in optoelectronic devices, high-power electronics, gas sensors, etc. However, the photoelectric properties of Ga2O3 still need to be improved before its [...] Read more.
Gallium oxide (Ga2O3), as a wide-bandgap semiconductor material, is highly expected to find extensive applications in optoelectronic devices, high-power electronics, gas sensors, etc. However, the photoelectric properties of Ga2O3 still need to be improved before its devices become commercially viable. As is well known, doping is an effective method to modulate the various properties of semiconductor materials. In this study, Zn–N co-doped Ga2O3 films with various doping concentrations were grown in situ on sapphire substrates by atomic layer deposition (ALD) at 250 °C, followed by post-annealing at 900 °C. The post-annealed undoped Ga2O3 film showed a highly preferential orientation, whereas with the increase in Zn doping concentration, the preferential orientation of Ga2O3 films was deteriorated, turning it into an amorphous state. The surface roughness of the Ga2O3 thin films is largely affected by doping. As a result of post-annealing, the bandgaps of the Ga2O3 films can be modulated from 4.69 eV to 5.41 eV by controlling the Zn–N co-doping concentrations. When deposited under optimum conditions, high-quality Zn–N co-doped Ga2O3 films showed higher transmittance, a larger bandgap, and fewer defects compared with undoped ones. Full article
(This article belongs to the Special Issue Nanoscale Photonics and Optoelectronics)
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