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Optical Chemical Sensor Using Intensity Ratiometric Fluorescence Signals for Fast and Reliable pH Determination
摘要： Optical pH sensors enable non-invasive monitoring of pH, yet in pure sensing terms, the potentiometric method of measuring pH is still vastly superior. Here, we report a full spectrometer-based optical pH sensor system consisting of sensor chemistry, hardware and software that for the first time is capable of challenging the performance of electrode-based pH meter in specific applications such as biopharmaceutical process monitoring and in single-use bioproduction. A highly photostable triangulenium fluorophore emitting at 590 nm was immobilized in an organically modified silicon matrix that allows for fast time-response by rapid diffusion of water in and out of the resulting composite polymer deposited on a polycarbonate substrate. Fluctuations from the fiber optical sensor hardware have been reduced by including a highly photostable terrylene-based reference dye emitting at 660 nm, thus enabling intensity-based ratiometric readouts. The dyes were excited by 505 nm light from a light emitting diode. The sensor was operational within a pH range of 4.6 and 7.6, and was characterized and demonstrated to have properties that are comparable to commercial pH electrodes considering time-response (t90 < 90 s), precision (0.03 pH-units) and drift.
关键词： ORMOSIL,optical pH sensors,pH optode,chemical sensors,ratiometric
更新于2025-09-23 15:23:52
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The Sensing Applications in U-Shape Structure Based on Dual Transparency Windows
摘要： We have researched a U-shape structure that consists of three vertical cavities coupled with bus wave-guide. The theoretical results based on the coupled mode theory are consistent with simulation results. We demonstrate that the interaction among two bright and one dark modes lead to dual plasmon induced transparency. Meanwhile, it is found that the lateral displacement S plays an important role in the transmission property, and the transmission dip with different transmittance in various lateral displacement S has been explained theoretically. Moreover, the nano sensor has a sensitivity of 1225 nm shift per refractive index unit, and the ?gure of merit is up to 62.5. The proposed structure has the advantages of simple and compact structure, easy fabrication, and the ultra-compact structure holds great potential to the control of light in highly integrated optical circuits and nano sensor.
关键词： Surface plasmons,nano sensors,coupled mode theory
更新于2025-09-23 15:23:52
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A Hyperspectral Imaging Instrumentation Architecture Based on Accessible Optical Disc Technology and Frequency-Domain Analyses
摘要： Hyperspectral imaging (HSI) is an emergent instrumentation technology with great potential in many applications, due to its ability to measure important spectral features. However, the widespread adoption of HSI requires the development of accessible (i.e., inexpensive and uncomplicated) HSI instrumentation architectures. In this paper, we present, design, develop, and evaluate an accessible HSI instrumentation architecture, with snapshot operation, based on the integration of readily available components and frequency multiplexing with Fourier analyses. In the experimental work, an incident image beam is divided into spatial image channels, each with an assigned dynamic binary code via a dynamic coded aperture. This dynamic coded aperture is constructed from repurposed diffractive optical disc technologies and is patterned with strategic opaque and transparent regions. When it is rotated by a motor, dynamic binary codes are used, along with Fourier analyses, to identify the diffraction of each spatial image channel. The spatially overlapped spectra from the diffraction are directed onto a charge-coupled device sensor, and each spatial image channel is distinguished through Fourier analyses. The resulting Fourier amplitude spectra are transformed into corresponding functions of wavelength, and this transformation is based on the experimental instrumentation geometry. The performance of the HSI instrumentation architecture is evaluated using a comparison with data from a commercial spectrometer. The presented HSI instrumentation architecture can be adapted for 2-D operation. Ultimately, the presented HSI instrumentation architecture can benefit regions of the world that have limited financial resources and a need for accessible HSI technologies.
关键词： Electromagnetic devices,optical diffraction,hyperspectral sensors,multispectral imaging
更新于2025-09-23 15:23:52
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Study on the preparation of CdTe nanocrystals on the surface of mesoporous silica and evaluation as modifier of carbon paste electrodes
摘要： Here CdTe nanocrystals were grown onto mesoporous silicas. The influence of the surface areas, volumes and pore diameters of the silica matrices on the spectroscopic properties of CdTe was evaluated. Emission properties of the CdTe were found to depend on the textural properties of silicas. Electrochemical characterization of different electrodes (unmodified carbon paste, and carbon paste modified with the mesoporous silica and with CdTe anchored onto mesoporous silica) evidenced that the presence of CdTe nanocrystals lead to a significant increase of the anodic peak referring to Cu2+ detection. The electrode with optimal characteristics responded to Cu2+ in the linear range from 5.0 × 10?8 to 2.3 × 10?6 mol L?1 and the calculated limit of detection was 6.4 × 10?8 mol L?1. The method developed here proved to be efficient for monitoring Cu2+ in sugar cane spirit (cacha?a), with quantitative results comparable to those obtained from Flame Atomic Absorbtion Spectroscopy.
关键词： CdTe nanocrystals,Mesoporous silicas,Electrochemical sensors
更新于2025-09-23 15:23:52
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Temperature fiber sensing of Li-ion batteries under different environmental and operating conditions
摘要： In this work, a network of fiber sensors has been developed for real time, in situ, and in operando multipoint monitoring the surface temperature distribution on a smartphone Li-ion battery (LiB). Different temperature and relative humidity conditions are considered, in order to mimic the LiB response in the dry, temperate, and cold climates. In total, the temperature variations that occur in five different locations of the LiB are monitored, during constant current charge and different discharge rates, under normal and abusive operating conditions, performing a thermal spatial mapping of the battery surface. In general, the sensors detect temperature variations according to the voltage signal change and faster variations of voltage usually translate in higher temperature rise at the LiB surface. For instance, under abusive discharge, where the voltage drop is fast, the temperature increases at least twice when compared to the normal operating conditions. Absolute temperature values as high as (65.0 ± 0.1) °C are detected by the optical sensor located near the electrodes, under the higher discharge rate (5.77 C) and dry climate. A thermal gradient is identified from the top to the bottom on the LiB surface during the experimental tests. A lower battery performance is observed when it operates under the cold climate, with maximum temperature variations of (30.0 ± 0.1) °C for the higher discharge rate. These results can be helpful to design of next generation of LiBs, improving a faster cooling in critical areas, in order to reduce accumulated heat and preventing consequences such as thermal runaway and failure.
关键词： Fiber Bragg grating sensors,Temperature monitoring,Abnormal operating conditions,Environment,Safety,Li-ion batteries
更新于2025-09-23 15:23:52
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Chemical Sensing Performance of Flower-Like ZnO/PSi Nanostructures via Electrochemical Impedance Spectroscopy Technique
摘要： ZnO nanostructures were synthesized on porous Si (PSi) structures using a method developed by this study known as electric field-assisted aqueous solution technique. The detailed characterization of this nanostructure was performed using atomic force microscopy, field emission scanning electron microscopy, x-ray diffraction, room-temperature photoluminescence and Raman spectroscopy. Electrochemical impedance spectroscopy (EIS) technique was used to detect two classifications of chemical solvents, namely polar and non-polar solvents. Nyquist plots in EIS were utilized to detect chemical solvents (ethanol, acetone, toluene and benzene) exposed to ZnO/PSi nanostructure arrays. The results showed that the grown flower-like ZnO nanostructure arrays served as good chemical sensors with high sensitivity and low power consumption. Meanwhile, the ZnO/PSi nanoflowers exposed to ethanol showed the highest sensitivity (94.6% response) compared to other chemical solutions with the least response exhibited by benzene (68.4% response). It was postulated that the interaction between the solution and oxygen species of ZnO/PSi nanostructure surface induced a resistance change resulting in the release of free electrons that migrated to the conduction band of ZnO/PSi nanoflower structures and reduced the number of surface-adsorbed oxygen species. Subsequently, the changes observed in the Nyquist semicircle diameter and Warburg impedance led to the chemical sensing response.
关键词： ZnO/PSi nanoflower,electric field-assisted aqueous solution technique,Chemical sensors,electrochemical impedance spectroscopy,Nyquist plot
更新于2025-09-23 15:23:52
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Quasi-one-dimensional silicon nanostructures for gas molecule adsorption: a DFT investigation
摘要： Porous structures offer an enormous surface suitable for gas sensing, however, the effects of their quantum quasi-confinement on their molecular sensing capacities has been seldom studied. In this work the gas-sensing capability of silicon nanopores is investigated by comparing it to silicon nanowires using first principles calculations. In particular, the adsorption of toxic gas molecules CO, NO, SO2 and NO2 on both silicon nanopores and nanowires with the same cross sections was studied. Results show that sensing-related properties of silicon nanopores and nanowires are very similar, suggesting that surface effects are predominant over the confinement. However, there are certain cases where there are remarked differences between the nanowire and porous cases, for instance, CO-adsorbed nanoporous silicon shows a metallic band structure unlike its nanowire counterpart, which remains semiconducting, suggesting that quantum quasi-confinement may be playing an important role in this behaviour. These results are significant in the study of the quantum phenomena behind the adsorption of gas molecules on nanostructure’s surfaces, with possible applications in chemical detectors or catalysts.
关键词： Sensing,Chemical sensors,Silicon nanowires,Density functional theory,Molecule adsorption,Porous silicon
更新于2025-09-23 15:23:52
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Near-Infrared fluorescence chemosensor based on isothiocyanate-aza-BODIPY for cyanide detection in ppb level: Applications in buffer media and living cell imaging
摘要： A near-infrared chemodosimeter based on an aza-BODIPY dye was designed and synthesized. The sensor contains isothiocyanate groups for cyanide ion sensing. The sensing function was illustrated via the fluorescence changes in near-infrared frequencies as well as chromogenic change which could be easily visualized with a detection limit of 19 ppb. The sensor provides high selectivity to CN? and discriminates other anions such as CH3COO?, HPO4 2?, HSO4 ?, NO3 ?, Cl?, F?, Br?, I?, ClO3 ?, CO3 2?, SO4 2?, and phenylalanine (Phe) in 50% PBS buffer/acetonitrile at physiological pH. The potential of the sensor for CN? detection in both aqueous buffer solutions and living cells imaging were demonstrated.
关键词： selectivity,cyanide,sensors,aza-BODIPY dyes,near-infrared fluorescence
更新于2025-09-23 15:23:52
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Synthesis, Structure, and Photoluminescence Properties of a Metal-Organic Framework with Hexagonal Channels: Selective Turn-On Sensing for Mg <sup>2+</sup> Ion
摘要： A three-dimensional Cd2+ framework (1) with wide one-dimensional hexagonal channels was prepared based on a tripodal tricarboxylate ligand possessing nitrogen donor atoms. The Cd atoms form a chain structure bridged by carboxylates and aqua ligands. Upon Mg2+ ion capture, the fluorescence emission of this porous material was 5.2 times greater than its Mg2+-free fluorescence. To the best of our knowledge, such enhancement has not been previously reported for metal–organic framework sensory systems. The sensing performance of 1 is reversible over repeated cycles of Mg2+ inclusion and release, revealing the reusability of this material. In the presence of other tested metal ions, Mg2+ ions were selectively detected owing to the operation of this “turn-on” mechanism. Thus, this platform is a promising sensor material for selective Mg2+ ion recognition.
关键词： Sensors,Luminescence,Metal-organic frameworks
更新于2025-09-23 15:23:52
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Optical properties of amine-functionalized graphene oxide
摘要： Important applications of graphene oxide (GO) its derivatives have been found in several areas: energy materials, water treatment, environmental, catalytic, photocatalytic, and biomedical technologies. Among them, the application of GO in optical biosensors has attracted ever-increasing interest in the past few years. In the present work, GO was amine-functionalized by a solvent-free one-step method with two aromatic amines: 1-aminopyrene (AP), and 2-aminofluorene (AF); and one aliphatic amine 1-octadecylamine (ODA). Particle size was estimated by field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Optical properties have been evaluated by application of photoluminescence (PL), FTIR, UV–VIS, and Raman spectroscopy. As a result, this study offers an efficient way to tune the optical properties due to their amine functionalization, favoring the development of optoelectronic and biological applications using graphene-based materials in the future.
关键词： Amine functionalization,Optical properties,Sensors,Graphene oxide
更新于2025-09-23 15:23:52