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Flattened fiber-optic ATR sensor enhanced by silver nanoparticles for glucose measurement
摘要： This paper proposes a novel fiber attenuated total reflection (ATR) sensor with silver nanoparticles (AgNPs) on the flattened structure based on mid-infrared spectroscopy for detecting low concentration of glucose with high precision. The flattened structure was designed to add the effective optical path length to improve the sensitivity. AgNPs were then deposited on the surface of the flattened area of the fiber via chemical silver mirror reaction for further improving the sensitivity by enhancing the infrared absorption. Combining the AgNPs modified flattened fiber ATR sensor with a CO2 laser showed a strong mid-infrared glucose absorption, with an enhancement factor of 4.30. The glucose concentration could be obtained by a five-variable partial least-squares model with a root-mean-square error of 4.42 mg/dL, which satisfies clinical requirements. Moreover, the fiber-based technique provides a pretty good method to fabricate miniaturized ATR sensors that are suitable to be integrated into a microfluidic chip for continuous glucose monitoring with high sensitivity.
关键词： Attenuated total reflection sensor,Mid-infrared spectroscopy,Flattened structure,AgNPs,Continuous glucose monitoring
更新于2025-09-04 15:30:14
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Pulsed High-Voltage Sensor with Nanosecond Transient Response Rise Time
摘要： A capacitive sensor for measuring the amplitude and time parameters of high voltage pulses in the 5–300 kV range is developed. The rise time of the transient response is 1.5 ns and the decay time is 170 μs. The standard measurement uncertainty for the amplitude of the voltage pulses with this sensor is found to be 2.9% by calibration.
关键词： sensor,nanosecond,high voltage
更新于2025-09-04 15:30:14
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A novel use of etched multi-mode fibre as magnetic field sensor
摘要： In this study, an optical fibre magnetic field sensor is experimentally demonstrated using chemical etched multimode fibre sandwiched between two single mode fibres. The obtained result of the magnetic field and refractive index response shows that the decreasing fibre diameter in the sensing region plays an important role to enhance the sensitivity of the device. The magnetic field sensing is based on a tunable refractive index (RI) property of magnetic fluid infiltrated into the capillary tube. The sensing system is verified by testing RI of different concentrations of sodium chloride (NaCl) solution before sealing in capillary tube. Experimental results show that the sensor with taper fibre diameter of 45?μm has relatively high magnetic field sensitivity of ～ 0.993?dB/mT ranging from 0 to 6?mT. The proposed devices find potential applications in magnetic field sensing.
关键词： optical fibre magnetic field sensor,sensitivity,chemical etched multimode fibre,refractive index,magnetic fluid
更新于2025-09-04 15:30:14
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Carboxymethylcellulose-based magnetic Au or Ag nanosystems: Eminent candidates in catalysis, sensing applications based on SERS, and electrochemistry
摘要： An increasing demand for metal gold- and/or silver-based nanomaterials in optics, catalysis, and electrochemical sensing research calls for the development of a new, clean, and environmentally friendly methodology for the production of metal-containing composites. Herein, we report a novel method for fabrication of dispersed carboxymethylcellulose stabilized iron oxide nanoparticles capable to adsorb silver and gold ions onto the surface. Simultaneously, Ag or Au ions are trapped on the magnetic carrier surface and reduced into metal nanoparticles without the action of another reducing agent. The magnetic silver nanocomposite with dumbbell-like structures and magnetic gold nanocomposite with strawberry-like structures, both of different composition (5, 10, and 20 wt.% metal contents), were prepared and characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, and atomic absorption spectroscopy. Subsequently, the prepared magnetic silver and gold nanocomposites (cMNPs-Ag and cMNPs-Au, respectively) were studied as sufficient candidates in catalysis, sensing applications based on SERS, and electrochemistry. The catalytic properties were demonstrated with the reduction of 4-nitrophenol to 4-aminophenol as a model reaction, where very high rate constants of nanocomposites ranging between 0.25 and 4.12 min?1 were determined. The TOF values were calculated to be from 20.87 to 95.34 min?1. Glassy carbon electrodes modified with cMNPs-Au or cMNPs-Ag nanocomposites were used for successful determination of H2O2 by means of cyclic voltammetry. Obtained results revealed the well-defined reduction peak around ?0.45 V indicating small overpotential necessary for H2O2 detection and detection limits were found to be 2.82 × 10?7 mol L?1 (cMNPs-Ag) and 3.04 × 10?7 mol L?1 (cMNPs-Au). Utilization of nanocomposites as active SERS substrates was demonstrated on the analysis of Rhodamine 6G. The determined enhancement factors were 2 × 107 (cMNPs-Au, 20 wt.% Au content) and 3.2 × 107 (cMNP-Ag, 20 wt.% Ag content).
关键词： Catalyst,Electrochemical nonenzymatic sensor,Carboxymethylcellulose,SERS substrate,Magnetic-gold and magnetic-silver nanocomposites
更新于2025-09-04 15:30:14
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Towards on-chip mid infrared photonic aerosol spectroscopy
摘要： We propose an on-chip mid-infrared (MIR) photonic spectroscopy platform for aerosol characterization to obtain highly discriminatory information on the chemistry of aerosol particles. Sensing of aerosols is crucial for various environmental, climatic, warfare threat detection, and pulmonary healthcare applications. Currently, chemical characterization of aerosols is performed using FTIR spectroscopy, yielding chemical ?ngerprinting because most of the vibrational and rotational transitions of chemical molecules fall in the IR range, and Raman spectroscopy. Both techniques use free space bench-top geometries. Here, we propose miniaturized on-chip MIR photonics-based aerosol spectroscopy consisting of a broadband spiral-waveguide sensor that signi?cantly enhances the particle-light interaction to improve sensitivity. The spiral waveguides are made of a chalcogenide glass material (Ge23Sb7S70) which shows a broad transparency over the IR range (1–10 lm). We demonstrate the sensing of N-methyl aniline-based aerosol particles with the device. We anticipate that the sensor will readily complement existing photonic resonator-based particle sizing and counting techniques to develop a uni?ed framework for on-chip integrated photonic aerosol spectroscopy.
关键词： N-methyl aniline,chalcogenide glass,on-chip mid-infrared photonic spectroscopy,aerosol characterization,spiral-waveguide sensor
更新于2025-09-04 15:30:14
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Hydrogen sensor for parabolic trough expansion tanks
摘要： The National Renewable Energy Laboratory and Acciona Energy North America are developing and implementing a process that addresses the issue of hydrogen buildup in parabolic trough power plants. We are pursuing a method that selectively removes hydrogen from the expansion tanks of the power plant to control hydrogen levels in the circulating heat-transfer fluid. As part of this effort, we are developing a sensor that measures hydrogen partial pressure in the expansion-tank headspace gas. During previous work, we demonstrated that our sensor design measures hydrogen levels over a wide partial pressure range from 1.33 mbar down to 0.003 mbar with an accuracy of ±20%. We acquired these results under limited conditions because we measured hydrogen partial pressure in gas mixtures of hydrogen and nitrogen only. In this paper, we report our most recent results in which we measured hydrogen partial pressures in gas mixtures that contain hydrogen, nitrogen, biphenyl, and diphenylether. Our results for this gas mixture were essentially the same as those obtained for the hydrogen/nitrogen mixture only, and they also had the same accuracy of ±20%. This level of accuracy is sufficient to evaluate the performance of a hydrogen mitigation process because hydrogen partial pressure in the expansion tank decreases more than an order of magnitude when the mitigation process is operating. We examined the palladium/silver membrane after completing these measurements and did not observe any signs of membrane deterioration or contamination due to exposure to biphenyl and diphenylether at 405oC. The membrane for these tests was 25 μm thick. For the next sensor design that we are developing in 2018, we are using a membrane that is 127 μm thick. This thickness is required for the membrane to withstand the 150 psi pressure drop across the membrane when exposed to actual headspace gas from the expansion tank. We performed initial tests in which we exposed a 127-μm-thick palladium alloy membrane to 400oC and 150 psi pressure drop and observed no signs of failure or gas leakage. Finally, we developed a transient model that accounts for hydrogen transport mechanisms within the sensor when measurements are made. Our model accounted for hydrogen diffusion through the boundary layer that is adjacent to the membrane and for hydrogen permeation across the membrane and into the permeate volume. Our modeling results agreed very closely with our experimental data when we assumed a boundary-layer thickness of 0.2 cm. This thickness is within the range of expected thicknesses for this gas composition, temperature, and pressure at minimum flowrate. Our model results showed that hydrogen diffusion through the boundary layer adjacent to the membrane is the rate-determining step for the transient pressure response when measuring hydrogen partial pressure.
关键词： hydrogen partial pressure,palladium/silver membrane,parabolic trough,expansion tanks,hydrogen sensor
更新于2025-09-04 15:30:14
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Research on the performance of a novel SPR sensor based on graded index multimode fiber
摘要： Purpose – This paper aims to propose and demonstrate a novel surface plasmon resonance (SPR)-sensing approach by using the fundamental mode beam based on a graded index multimode fiber (GIF). The proposed SPR sensor has high sensitivity and controllable working dynamic range, which expects to solve the two bottlenecks of fiber SPR sensor, including low sensitivity and the difficulty in multichannel detection. Design/methodology/approach – The low-order mode of the GIF to SPR sense, which keeps the sensitivity advantage of the single-mode fiber SPR sensor, is used. By using this new SPR sensor, the effect of light incident angle and gold film thickness on working dynamic range was studied. According to the study results, the smaller is the incident angle, the larger is the SPR working dynamic range and the longer is the resonance wavelength with a fixed gold film thickness; the larger is the gold film thickness, the longer is the resonance wavelength with a fixed grinding angle. After the parameter optimization, the sensitivity of these two parameter-adjusting methods reach 4,442 and 3031 nm/RIU. Originality/value – When the grinding angle of the GIF increases, the dynamic range of the resonance wavelength increases and has a redshift, sensitivity increases, and the resonance valley becomes more unobvious with a fixed gold film thickness. Similarly, when gold film thickness increases, the dynamic range of the resonance wavelength increases and has a redshift, sensitivity increases, and the resonance valley becomes more unobvious with a fixed grinding angle. These adjusting performance aforementioned lay the foundation for solving of the fiber-based SPR multichannel detection and increasing of the fiber-based SPR sensor sensitivity, which has a good application value.
关键词： Dynamic range,Sensitivity,GIF,SPR sensor
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - V?ster?s, Sweden (2018.9.3-2018.9.6)] 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - A PSE-Coated Interdigital Resonator Gas Sensor for Agricultural Applications
摘要： This paper presents a microwave gas sensor based on interdigital resonator structure coating with gas sensing material of poly (styrene-co-maleic acid) partial isobutyl/methyl mixed ester (PSE). This sensor was designed on the center of coplanar waveguide (CPW) to operate at 4 GHz with rejection characteristic. The measured results for five samples of ammonia hydroxide concentration (50, 200, 500, 1000, and 2000 ppm) under a static system in the closed chamber at room temperature were obtained. The levels of gas concentration can be impressively detected by measuring the transmission coefficient changes. The proposed sensor can be employed for several applications such as sensing the gas generating from agricultural products.
关键词： interdigital resonator,microwave gas sensor,PSE-coated
更新于2025-09-04 15:30:14
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[IEEE ICASSP 2018 - 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - Calgary, AB (2018.4.15-2018.4.20)] 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - Image Reconstruction for Quanta Image Sensors Using Deep Neural Networks
摘要： Quanta Image Sensor (QIS) is a single-photon image sensor that oversamples the light field to generate binary measurements. Its single-photon sensitivity makes it an ideal candidate for the next generation image sensor after CMOS. However, image reconstruction of the sensor remains a challenging issue. Existing image reconstruction algorithms are largely based on optimization. In this paper, we present the first deep neural network approach for QIS image reconstruction. Our deep neural network takes the binary bitstream of QIS as input, learns the nonlinear transformation and denoising simultaneously. Experimental results show that the proposed network produces significantly better reconstruction results compared to existing methods.
关键词： single-photon imaging,Quanta Image Sensor,deep neural networks,image reconstruction
更新于2025-09-04 15:30:14
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Highly sensitive vector curvature sensor based on two juxtaposed fiber Michelson interferometers with Vernier-like effect
摘要： In this paper, a highly sensitive vector curvature sensor based on two juxtaposed fiber Michelson interferometers (MI) with Vernier-like effect has been proposed and verified. Different from the structures of the conventional Vernier effect which are composed of the cascaded elements, the proposed configuration consists of two juxtaposed MIs. A triple-core fiber (TCF) is connected with a quite short piece of dual-side-hole fiber (DSHF), and the core of the DSHF and the two eccentric cores of the TCF are respectively constituted two juxtaposed MIs. Vernier-like effect is caused by the very small refractive index difference between the two eccentric cores of the TCF. The most outstanding feature of the proposed structure is that the two MIs are both sensitive to curvature with opposite sensitivities, which makes the curvature sensitivity magnification factor twice that of the conventional Vernier effect structure. Experimental results show that the curvature sensitivity of the structure can reach -60.84 nm/m-1.
关键词： triple-core fiber,curvature sensor,interferometer
更新于2025-09-04 15:30:14