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An Optical MEMS Acoustic Sensor Based on Grating Interferometer
摘要： Acoustic detection is of great signi?cance because of its wide applications. This paper reports a Micro-Electro-Mechanical System (MEMS) acoustic sensor based on grating interferometer. In the MEMS structure, a diaphragm and a micro-grating made up the interference cavity. A short-cavity structure was designed and fabricated to reduce the impact of temperature on the cavity length in order to improve its stability against environment temperature variations. Besides this, through holes were designed in the substrate of the grating to reduce the air damping of the short-cavity structure. A silicon diaphragm with a 16.919 μm deep cavity and 2.4 μm period grating were fabricated by an improved MEMS process. The fabricated sensor chip was packaged on a conditioning circuit with a laser diode and a photodetector for acoustic detection. The output voltage signal in response to an acoustic wave is of high quality. The sensitivity of the acoustic sensor is up to ?15.14 dB re 1 V/Pa @ 1 kHz. The output signal of the high-stability acoustic sensor almost unchanged as the environment temperature ranged from 5 ?C to 55 ?C.
关键词： interferometry,stability,acoustic sensors,MEMS,grating
更新于2025-11-28 14:23:57
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Arc-Induced Long Period Gratings in Erbium-Doped Fiber
摘要： In this paper, we report about the fabrication of long period gratings (LPGs) directly into an Erbium-doped fiber, by using the electric arc discharge technique. The attention is focused on the writing process and the resulting properties, by considering gratings with different periods and measuring their spectra over a wide wavelength range. The LPGs show high order attenuation bands with tunable resonance wavelengths and depths up to 30 dB, while the lengths of the final devices are in range 20–45 mm. The polarization-dependent loss of these LPGs is also measured, for the first time in this kind of fiber. As further novelty, the influence of surrounding refractive index, applied strain, and temperature is investigated and discussed in comparative manner. Based on the achieved results, this fabrication procedure can be adapted to a specific application, for example in optical communications, signal processing, and sensing fields.
关键词： waveguide devices,Fiber gratings,fiber optics systems,sensors
更新于2025-11-28 14:23:57
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In-fiber Mach-Zehnder Interferometer Exploiting a Micro-cavity For Strain and Temperature Simultaneous Measurement
摘要： An in-fiber Mach-Zehnder interferometer (MZI) with a micro-cavity (MC) exploited for strain and temperature simultaneous measurement. The research is carried out experimentally and simulatively. The MC fabricated by splicing a hollow quartz tube between two single mode fibers serves as a light splitter for the two arms of MZI beams and a Fabry–Pérot interferometer (FPI) component at the same time. Thus both functions of a Mach-Zehnder interferometer and a Fabry–Pérot interferometer were implemented in a single sensor. With aid of the different response of the MZI and FPI to the strain and temperature, this device can achieve a simultaneous measurement and the strain/temperature cross-sensitivity issue has been alleviated. Such a composite interference structure, possess with the characteristics of easy making, high performance-price ratio provides a promising approach to implement strain and high-temperature simultaneous measurement.
关键词： Fabry–Pérot interferometer,Fiber Optics Sensors,Mach-Zehnder interferometer
更新于2025-11-28 14:23:57
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Genetically encoded fluorescent indicators for imaging intracellular potassium ion concentration
摘要： Potassium ion (K+) homeostasis and dynamics play critical roles in biological activities. Here we describe three genetically encoded K+ indicators. KIRIN1 (potassium (K) ion ratiometric indicator) and KIRIN1-GR are F?rster resonance energy transfer (FRET)-based indicators with a bacterial K+ binding protein (Kbp) inserting between the fluorescent protein FRET pairs mCerulean3/cp173Venus and Clover/mRuby2, respectively. GINKO1 (green indicator of K+ imaging) is a single fluorescent protein-based K+ indicator constructed by insertion of Kbp into enhanced green fluorescent protein (EGFP). These indicators are suitable for detecting K+ at physiologically relevant concentrations in vitro and in cells. KIRIN1 enabled imaging of cytosolic K+ depletion in live cells and K+ efflux and reuptake in cultured neurons. GINKO1, in conjunction with red fluorescent Ca2+ indicator, enable dual-color imaging of K+ and Ca2+ dynamics in neurons and glial cells. These results demonstrate that KIRIN1 and GINKO1 are useful tools for imaging intracellular K+ dynamics.
关键词： FRET-based sensors,potassium ion imaging,single fluorescent protein sensors,intracellular K+ dynamics,genetically encoded indicators
更新于2025-11-21 11:24:58
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Pyrophosphate Prompted Aggregation-Induced Emission: Chemosensor Studies, Cell Imaging, Cytotoxicity, and Hydrolysis of the Phosphoester Bond with Alkaline Phosphatase
摘要： Two zinc complexes [(Zn)2(L2)2Cl2(DMSO)2] (R1) and [Zn(L2)2(NO3)2(H2O)2] (R2) were synthesized and characterized with various spectroscopic data. The single X-ray structure determination reveals that complex R1 is dinuclear and tetrahedral in geometry, while complex R2 is mononuclear and octahedral in geometry. Further, both zinc complexes were investigated for pyrophosphate sensing in an aqueous medium. Complex R1 is found to be selective towards pyrophosphate; it leads to 5.5-fold enhancement in the emission intensity due to aggregation-induced emission. However, complex R2 has shown binding with all, ATP, AMP, ADP, and pyrophosphate, which is attributed to the chelate effect. Consequently, complex R1 was utilized for the intracellular detection of pyrophosphate in HeLa cells. Furthermore, the PPi based zinc complex R1 is also used as a bio-analytical tool to construct a real-time fluorescence assay for the enzymatic activity of alkaline phosphatases (ALP).
关键词： Intracellular detection,Sensors,Fluorescence,Zinc,ALP activity,Pyrophosphate
更新于2025-11-21 11:24:58
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Fabrication of gold-silver core-shell nanoparticles for performing as ultrabright SERS-nanotags inside human ovarian cancer cells
摘要： This paper presents the fabrication and characterization of new gold-silver core-shell nanoparticles labeled with para-mercaptobenzoic acid (4MBA) molecules and demonstrates their use as SERS-nanotags with ultra-bright traceability inside cells and ability to convey spectrally-coded information about the intracellular pH by means of Surface-Enhanced Raman Spectroscopy (SERS). Unlike to previous reported studies, our fabrication procedure includes in the first step the synthesis of chitosan-coated gold nanoparticles as a seed material with subsequent growing of a silver shell. The bimetallic core-shell structure is revealed by transmission electron microscopy (TEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray elemental mapping (EDX) and the presence of two interacting localized surface plasmon resonance (LSPR) modes in UV-Vis extinction spectrum. The high SERS activity and sensitivity of as fabricated 4MBA-chit-Au-AgNPs nano-constructs to different pH in solution is investigated under 532 and 633 nm laser lines excitation. Next, in view of future studies in cancer diagnosis, the in vitro antiproliferative effects of SERS-nanotags against human ovarian adenocarcinoma cells (NIH:OVCAR-3) are evaluated. The capacity to operate as bright SERS nanotags with precise localization at a single cell level as well as intracellular pH indicators is clearly demonstrated by performing cell imaging under scanning confocal Raman microscopy.
关键词： core-shell nanoparticles,pH sensors,ovarian cancer cells,chitosan,SERS tags
更新于2025-11-21 11:24:58
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Flexible and Ultrasensitive Piezoelectric Composites Based on Highly (00l)‐Assembled BaTiO <sub/>3</sub> Microplatelets for Wearable Electronics Application
摘要： Piezoelectric wearable electronics with flexibility and high sensitivity have received increasing attention in the fields of health monitoring, flexible robots, and artificial intelligence. Here, a flexible organic–inorganic hybrid composite for wearable electronics application based on (00l)-aligned BaTiO3 (BT) single-crystal microplatelets is prepared by layer-by-layer self-assembly technology. For the polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE))/BT single-crystal microplatelets composite film, the sensitivity is nearly 20 times higher than that of its counterparts of P(VDF-TrFE)/BT microparticles composite film and pure P(VDF-TrFE) film. The orderly alignment of BT microplatelets also has been found advantageous to the strength of the composite film. The tensile strength is up to 204.3 MPa even at a high inorganic phase content of 53.8 wt% in P(VDF-TrFE)/BT single-crystal microplatelets composite film, which is four times that of pure P(VDF-TrFE) film. Moreover, the flexible piezoelectric wearable device based on P(VDF-TrFE)/BT single-crystal microplatelets film effectively provides detailed information for monitoring human activities such as pronunciation, frequency, and waveform of pulse beating, and motion states. This high sensitivity, high strength, and flexible piezoelectric composite provides much potential on the applications of wearable equipments and health monitoring devices.
关键词： organic–inorganic hybrids,wearable sensors,flexible piezoelectric composites,BaTiO3
更新于2025-11-21 11:01:37
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Two pH-responsive fluorescence probes based on indole derivatives
摘要： Two new pH ?uorescent probes 2,8-bis((E)-2-(1,1-dimethyl-1H-benzo[e]indol-2-yl)vinyl)-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine (1) and 2,8-bis((E)-2-(3,3-dimethyl-3H-indol-2-yl)vinyl)-6H,12H-5,11-methanodibenzo[b,f] [1,5]diazocine (2) were designed and synthesized via ethylene bridging of the Tr?ger's Base (TB) framework and indole derivatives. As the protonation of nitrogen atoms of indole derivatives, both probes displayed the signi?cant pH-dependent spectral properties. The probing behavior toward pH variations indicated that probes exhibited excellent pH dependent behavior in the pH ranges of 2.07–7.01 (1) and 1.96–7.01 (2), especially possessing good linear response in the pH ranges of 2.50–4.00. The emissions of 1 can be reversibly switched between brilliant yellow and dark states by protonation and deprotonation. Also, the yellow-green ?uorescence emission of 2 could be quenched upon protonation. Such behaviors enable them to work as turn-o? ?uorescent pH sensors in the solution state. Furthermore, protonation and deprotonation on indole moiety nitrogen of the probe 1 and 2 provided a sensing mechanism for pH changes. In addition, both probes performed good photostability, high selectivity and excellent reversibility.
关键词： Sensors,Fluorescent probe,pH detection,Luminescence,Indole derivatives
更新于2025-11-19 16:56:35
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POSS: A Morphology-Tuning Strategy to Improve the Sensitivity and Responsiveness of Dissolved Oxygen Sensor
摘要： Dissolved oxygen (DO) plays a crucial role in environment, food processing, and biotechnology. Although several physical-doping DO probes have been developed, a sensitive and reliable sensor for real-time and non-invasive DO detection in bioprocess is still challenging. Here we demonstrate a morphology-tuning strategy to improve the sensitivity and responsiveness of DO polymeric sensors (P(Pt-TPP-TFE-Ad) and P(Pt-TPP-TFE-POSS)) by decorating with the same platinum(II) porphyrins and different morphology-tunable moieties in supporting matrix. Experimental results manifest the sensitivity and response of sensors increase with size effect of the morphology-tunable moiety in due that the bulky morphology-tunable moiety facilitates the formation of interconnected and porous network that can promote oxygen permeability. Additionally, P(Pt-TPP-TFE-POSS) features excellent linear Stern-Volmer quenching, superior stability, and reversible response, thereby permitting the real-time and non-invasive quantification of DO during cephalosporin C fermentation. Our work offers an ideal tool for online sensing of DO in industrial and biological applications.
关键词： porphyrin,sensors,biofermentation,morphology-tuning,dissolved oxygen
更新于2025-11-19 16:56:35
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Highly Sensitive and Selective Fluorescent Sensor based on a Multi-Responsive Ultrastable Amino-Functionalized Zn(II)-MOF for Hazardous Chemicals
摘要： A microscale amino-functionalized Zn(II)-MOF, namely [Zn(NH2-bdc)(4,4’-bpy)] (1) (NH2-H2bdc = 2-amino-1,4-benzenedicarboxylic acid and 4,4’-bpy = 4,4’-bipyridine), has been successfully synthesized, structurally characterized and further utilized as multi-responsive fluorescent sensor for highly sensitive and selective detection of Cr(VI) and 2,4,6-trinitrophenol (TNP). Compound 1 features non-porous 5-fold interpenetrated 3D framework with the Lewis basic sites including the uncoordinated amino and carboxylate groups on the framework for anchoring and recognizing the guest. 1 exhibits not only excellent water and thermal stability but also tolerance to acidic and basic media over an extensive pH range of 2-12. This ultrastable material can sensitively and selectively detect Cr2O7 2- and CrO4 2- in water based on the luminescent quenching with relatively low limits of detection (2.21 μM for CrO4 2- and 1.30 μM for Cr2O7 2-). Moreover, the unprecedented solvent-dependent luminescent response of 1 as a fluorescent probe for high-efficiency TNP detection was observed. Significantly, 1 not only displays high sensitive fluorescent enhancement upon TNP binding in ethanol but also exhibits fluorescent quenching toward TNP in water with very low limits of detection of 4.47 nM and 0.32 μM in ethanol and water, respectively. This work reports the first example of the utilization of MOF as a sensor for the detection of TNP based on dual responsive luminescence. Importantly, 1 can be simply and rapidly regenerated, displaying excellent recyclability after the sensing experiments.
关键词： Multi-responsive fluorescent sensors,Fluorescent quenching,Metal-organic framework,2,4,6-trinitrophenol,Fluorescent enhancement,Cr(VI)
更新于2025-11-19 16:46:39