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Optical Sensing Properties of ZnO Nanoparticles Prepared by Spray Pyrolysis
摘要： We studied the optical sensing properties of ZnO nanoparticles prepared by spray pyrolysis. To investigate their optical sensing performance, we incubated peptides on ZnO nanoparticles. The photoluminescence (PL) peak intensity of peptides on the ZnO nanoparticles was higher than that of peptides on the ZnO film or on the glass plate. This observed PL enhancement is attributed to the optical confinement of ZnO nanoparticles. The low-temperature spectra displayed a strong exciton emission peak with multiple sidebands, attributed to the bound exciton and its longitudinal optical phonon sidebands. The strong exciton emission is thought to be the combined effect of optical confinement due to the nanoparticle geometry, reduction of defect emission by thermal annealing, and reduction of non-radiative relaxation at low temperatures.
关键词： Exciton,ZnO Nanoparticles,Photoluminescence,Peptide,Optical Sensing
更新于2025-09-19 17:15:36
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A series of aromatric-amine-cored fluorescent emitters for amplified spontaneous laser emission and emission turn-on sensing
摘要： In this paper, five boron dipyrromethene dyes were designed with aromatric-amine-cored structure. Their molecular structure and photophysical performance were discussed in detail in various solvents. It was found that these five dyes were highly fluorescent ones in toluene with emission quantum yield higher than 95%. Amplified spontaneous emission (ASE) performance of these fluorescent dyes was then analyzed in toluene. Efficient and promising ASE spectra peaking at ~545 nm were observed for four of these fluorescent dyes with full width at half maximum value of ~5 nm and ASE efficiency up to 9%. It was confirmed that aromatric-amine-cored structure was positive to improve ASE performance. The reason for ASE missing in one of these fluorescent dyes was revealed as the vibrational relaxation of its N-H group. In solvent MeCN, however, this dye showed an interesting phenomenon, emission turn on effect towards Hg(II). Its sensing performance and sensing mechanism were discussed in detail as well. Good linear response and high selectivity were found for both colorimetric sensing and emission turn on sensing.
关键词： ASE,emission turn on,laser dyes,optical sensing
更新于2025-09-19 17:13:59
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Scanning laser triangulation sensor geometry maintaining imaging condition
摘要： This work deals with the system design, control and the experimental results of a scanning laser sensor in which the optical path is scanned by a novel high performance compact fast steering mirror (FSM). The system design satisfies the Scheimpflug condition even though only the illumination path is scanned, such that an FSM with a small aperture size and high bandwidth can be used. To scan the area of interest with the FSM, raster trajectories are employed, which provide an uniform spatial resolution over the scan area. To track the trajectory a feedback controller is designed using the H-approach, such that a closed loop bandwidth of 1.4 kHz is achieved. The FSM can follow triangular signals up to 200 Hz with the maximum actuation range of ±3?. This enables a framerate of up to two frames per second for an image with 100x100 pixels. With the scanning system a maximum spatial resolution of 60 μm and a scan range of 25 mm can be achieved.
关键词： Optical Sensing and Sensors,Precision measurements,Laser Sensor,Fast Steering Mirror,Scheimpflug Condition,3D Sensor,Absolute measurement,System Design
更新于2025-09-16 10:30:52
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[OSA Optical Fiber Sensors - Lausanne (2018..-..)] 26th International Conference on Optical Fiber Sensors - Highly sensitive fiber temperature sensor based on antiresonant effect cascaded with multimode interference
摘要： We experimentally demonstrated a highly sensitive fiber temperature sensor based on anti-resonant effect cascaded with multimode interference, the sensitivity of 26.73 pm/°C and -275.39 pm/°C corresponding to the aforementioned two mechanisms can be respectively obtained.
关键词： Optical sensing and sensors,Fiber optics components,Integrated optical devices,Fiber optics sensors
更新于2025-09-12 10:27:22
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Optical in-process height measurement system for process control of laser metal-wire deposition
摘要： We propose an in-process height measurement system for a weld bead and feedback control system for wire-feeding speed for high-quality laser deposition. Metal additive manufacturing, especially laser metal-wire deposition, is effective for complex shape fabrication and repair processing. However, we must control the gap between a weld bead and a feed wire in an optimal range for high-quality deposition. Conventionally, the Z-stage pitch for multi-layer deposition must be precisely adjusted by each deposition shape. In this paper, we design an in-process height measurement system that is integrated in a laser processing head, which measures the weld bead height by a line section method. We decreased the influence of the intense thermal radiation generated from a melt pool by inserting the band-pass filter of the line beam’s wavelength in the imaging system and optimizing its line laser power. Consequently, our system can measure the weld bead height near the melt pool, which is 4 mm in front of it. Next we show that our proposed system can measure the weld bead height during wire-laser metal deposition with 50-μm accuracy by comparing its value to the true value. Finally, we achieved a cylinder shape deposition of 50-mm height, regardless of the Z-stage pitch and the cylinder diameter of the multi-layer deposition, by controlling the wire-feeding speed based on the measured weld bead height.
关键词： Laser Metal Deposition,Light Section Method,Optical Sensing,Height Measurement,Process Monitoring,Additive Manufacturing
更新于2025-09-12 10:27:22
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A turn-on graphene quantum dot and graphene oxide based fluorometric aptasensor for the determination of telomerase activity
摘要： A turn-on fluorometric assay is described for determination of the activity of enzyme telomerase. For this purpose, graphene quantum dots (GQDs) were first modified with the telomeric sequence (5′-amino-AATCCGTCGAGCAGAGTT-3′) via a condensation reaction. Injection of graphene oxide causes instant quenching of the blue fluorescence of the GQDs. Addition of cell extract containing telomerase, triggers the extension of telomer via addition of specific sequence (TTAGGG)n to its 3′ end. Fluorescence, best measured at excitation/emission wavelengths of 390/446 nm, is subsequently restored due to folding of the extended telomeric sequence into G-quadruplex structure. The method was applied to the determination of telomerase activity in crude cell extracts of as little as 10 HeLa cells. The linear dynamic range extends from 10 to 6500 cells.
关键词： G-quadruplex,Biosensors,Fluorescence,Optical sensing,Biomarker,Cancer detection,Nanoprobe
更新于2025-09-12 10:27:22
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Highly Luminescent Ternary Nanocomposite of Polyaniline, Silver Nanoparticles and Graphene Oxide Quantum Dots
摘要： Quantum dots (QDs) with photostability show a potential application in optical sensing and biological imaging. In this work, ternary nanocomposite (NC) of high fluorescent polyaniline (PANI)/2-acrylamido-2-methylpropanesulfonic acid (AMPSA) capped silver nanoparticles (NPs)/graphene oxide quantum dots (PANI/Ag (AMPSA)/GO QDs) have been synthesized by in situ chemical oxidative polymerization of aniline in the presence of Ag (AMpSA) nps and Go QDs. Ag (AMpSA) nps and Go QDs were prepared by AgNO3 chemical reduction and glucose carbonization methods, respectively. The prepared materials were characterized using UV-visible, Fourier transform infrared (FTIR), photoluminescence and Raman spectroscopies, X-Ray diffractometer (XRD) and high- resolution transmission electron microscopy (HRTEM). HRTEM micrographs confirmed the preparation of GO QDs with an average size of 15 nm and Ag (AMPSA) NPs with an average size of 20 nm. PANI/Ag (AMPSA)/GO QDs NC showed high and stable emission peak at 348 nm. This PANI/Ag (AMPSA)/GO QDs NC can emerge as a new class of fluorescence materials that could be suitable for practical sensing applications.
关键词： Fluorescent materials,Biological imaging,Quantum dots,Graphene oxide quantum dots,Polyaniline,Optical sensing,Polymeric nanocomposites,Silver nanoparticles
更新于2025-09-11 14:15:04
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Highly cooperative fluorescence switching of self-assembled squaraine dye at tunable threshold temperatures using thermosensitive nanovesicles for optical sensing and imaging
摘要： Thermosensitive fluorescent dyes can convert thermal signals into optical signals as a molecular nanoprobe. These nanoprobes are playing an increasingly important part in optical temperature sensing and imaging at the nano- and microscale. However, the ability of a fluorescent dye itself has sensitivity and accuracy limitations. Here we present a molecular strategy based on self-assembly to overcome such limitations. We found that thermosensitive nanovesicles composed of lipids and a unique fluorescent dye exhibit fluorescence switching characteristics at a threshold temperature. The switch is rapid and reversible and has a high signal to background ratio (>60), and is also highly sensitive to temperature (10–22%/°C) around the threshold value. Furthermore, the threshold temperature at which fluorescence switching is induced, can be tuned according to the phase transition temperature of the lipid bilayer membrane forming the nanovesicles. Spectroscopic analysis indicated that the fluorescence switching is induced by the aggregation-caused quenching and disaggregation-induced emission of the fluorescent dye in a cooperative response to the thermotropic phase transition of the membrane. This mechanism presents a useful approach for chemical and material design to develop fluorescent nanomaterials with superior fluorescence sensitivity to thermal signals for optical temperature sensing and imaging at the nano- and microscales.
关键词： fluorescence switching,optical sensing,nanovesicles,thermosensitive fluorescent dyes,imaging
更新于2025-09-11 14:15:04
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Photonic Microcavity-Enhanced Magnetic Plasmon Resonance of Metamaterials for Sensing Applications
摘要： We investigate photonic microcavity-enhanced magnetic plasmon (MP) resonance in metamaterials for high-quality refractive index sensing. The metamaterials are consisting of a top periodic array of U-shaped metallic split-ring resonators (SRRs), a middle dielectric layer, and a bottom metallic backed plate. The top metallic SRRs that are placed at about Bragg distance above the bottom metallic plate constitute a photonic microcavity. Because the MP resonance excited in metallic SRRs is coupled to the photonic microcavity mode supported by the photonic microcavity, the radiative damping of the MP resonance is strongly reduced and consequently its linewidth is decreased dramatically. Benefiting from the narrow linewidth, large modulation depth, and giant magnetic field enhancement at the MP resonance, the cavity-coupled metamaterial sensor has very high sensitivity (S =400 nm/RIU, S* =26/RIU) and figure of merit (FOM =33, FOM* =4215), which suggests that the proposed metamaterials have potential in applications of plasmonic biosensors.
关键词： Optical sensing and sensors,Narrow linewidth,Magnetic field enhancement,Photonic microcavity,Metamaterials
更新于2025-09-10 09:29:36
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All-optical mode conversion and temperature sensing via transient-grating in step-index fiber
摘要： We demonstrate the formation of Kerr-induced transient long period grating in a standard single-mode ?ber (SMF28) using sub-nanosecond laser pulses and it’s application as an ef?cient all-optical mode conversion and temperature sensing. The ?ber supports LP01 and LP11 spatial modes at 1064 nm wavelength. The beating between two guided modes induces refractive index grating exploiting the Kerr effect. The probe beam co-propagating with the pump at the same wavelength but with different polarization, exhibits ef?cient mode conversion ef?ciency from LP01 to LP11 mode. Temperature sensitivity is measured owing to the change in mode conversion ef?ciency due to the shift in resonant peak wavelength with the increase in temperature. The change in temperature is manifested by the change in spectral power of probe beam at the output. Experimental result demonstrates an average temperature sensitivity of 0.15 Watt/oC. The transient nature of the grating with high sensitivity makes our approach unique from the existing results and can open a route for potential applications.
关键词： Fiber nonlinear optics,optical sensing,Fiber mode coupling
更新于2025-09-10 09:29:36