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Ole Bang - One of the best experts on this subject based on the ideXlab platform.

  • temperature insensitive hysteresis free highly sensitive polymer optical fiber bragg grating Humidity sensor
    Optics Express, 2016
    Co-Authors: Getinet Woyessa, Alessio Stefani, Kristian Nielsen, Christos Markos, Ole Bang
    Abstract:

    The effect of Humidity on annealing of poly (methyl methacrylate) (PMMA) based microstructured polymer optical fiber Bragg gratings (mPOFBGs) and the resulting Humidity responsivity are investigated. Typically annealing of PMMA POFs is done in an oven without Humidity control around 80°C and therefore at low Humidity. We demonstrate that annealing at high Humidity and high temperature improves the performances of mPOFBGs in terms of stability and Sensitivity to Humidity. PMMA POFBGs that are not annealed or annealed at low Humidity level will have a low and highly temperature dependent Sensitivity and a high hysteresis in the Humidity response, in particular when operated at high temperature. PMMA mPOFBGs annealed at high Humidity show higher and more linear Humidity Sensitivity with negligible hysteresis. We also report how annealing at high Humidity can blue-shift the FBG wavelength more than 230 nm without loss in the grating strength.

  • Humidity insensitive TOPAS polymer fiber Bragg grating sensor
    Opt. Express, 2011
    Co-Authors: Wu Fu-yuan, Lutful Khan, Kyriacos Kalli, Alessio Stefani, David J. Webb, Ole Bang
    Abstract:

    We report the first experimental demonstration of a Humidity insensitive polymer optical fiber Bragg grating (FBG), as well as the first FBG recorded in a TOPAS polymer optical fiber in the important low loss 850nm spectral region. For the demonstration we have fabricated FBGs with resonance wavelength around 850 nm and 1550 nm in single-mode microstructured polymer optical fibers made of TOPAS and the conventional poly (methyl methacrylate) (PMMA). Characterization of the FBGs shows that the TOPAS FBG is more than 50 times less sensitive to Humidity than the conventional PMMA FBG in both wavelength regimes. This makes the TOPAS FBG very appealing for sensing applications as it appears to solve the Humidity Sensitivity problem suffered by the PMMA FBG.

Junming Liu - One of the best experts on this subject based on the ideXlab platform.

  • large and fast single crystal resistive Humidity Sensitivity of metal pnictide halides containing van der waals host guest interactions
    Chemistry-an Asian Journal, 2014
    Co-Authors: Xiaoming Jiang, Zhibo Yan, Dan Liu, Kefeng Wang, Guocong Guo, Junming Liu
    Abstract:

    Two new metal pnictide halides, (Hg(9.75)As(5.5))(GaCl4)3 and (Hg13Sb8)(ZnBr4)4, have been prepared by solid-state reactions. Their structures feature 3D cationic host frameworks built of mercury pnictide polyhedra and form 1D tunnels filled with discrete guest halide polyanions; the guests and hosts are assembled by van der Waals interactions. Both complexes exhibit good single-crystal Humidity Sensitivity, with a Humidity Sensitivity factor as big as three orders of magnitude, a quick resistance response, fast recovery, and good reproducibility. This study provide a new way to design promising resistive Humidity detectors by introducing van der Waals host-guest interactions into their structures.

Siyan Peng - One of the best experts on this subject based on the ideXlab platform.

  • a new pnictidehalide with van der waals host guest interactions exhibiting both geometric spin frustration and resistive Humidity Sensitivity
    New Journal of Chemistry, 2018
    Co-Authors: Siyan Peng, Liusai Yang, Mingshui Yao
    Abstract:

    A new metal pnictidehalide (Hg6P4)(CrCl6)Cl has been prepared by solid-state reaction. Its structure features a 3-D perovskite-like host octahedral network and discrete octahedral (CrCl6)3− and Cl− guest ions assembled by weak van der Waals interactions. The nearest neighboring Cr3+ ions are antiferromagnetically coupled with each other, and the complex can be regarded as a geometric spin frustrated system. Electronic structure, optical dielectric constants and magnetic coupling parameters were calculated using the LDA+U method. The complex exhibits good resistive Humidity Sensitivity with Humidity response as big as four orders of magnitude, quick resistance response, fast recovery, and good reproducibility. The complex provides a new way to realize multifunctional properties driven by weak van der Waals interactions.

Ying Zhou - One of the best experts on this subject based on the ideXlab platform.

  • highly sensitive Humidity sensor based on quartz crystal microbalance coated with zno colloid spheres
    Sensors and Actuators B-chemical, 2013
    Co-Authors: Juan Xie, Hu Wang, Yuanhua Lin, Ying Zhou
    Abstract:

    Abstract Different sizes of ZnO colloid spheres were coated on quartz crystal microbalance (QCM) by the self-assembly method. The device exhibits excellent Humidity sensing properties in the whole Humidity range from 11% to 95%, such as high Sensitivity, good linearity, and fast response/recovery time. The results showed that the Humidity Sensitivity of these sensors increased with increasing relative Humidity (RH). Furthermore, the Humidity Sensitivity enhanced with increasing size of ZnO colloid spheres. We also discussed the adsorption and desorption of water molecules on different sizes of ZnO colloid spheres in different Humidity.

  • Humidity sensors based on zno tio2 core shell nanorod arrays with enhanced Sensitivity
    Sensors and Actuators B-chemical, 2011
    Co-Authors: Leilei Gu, Ying Zhou, Kaibo Zheng, Juan Li, Xiaoliang Mo, Greta R Patzke, Guorong Chen
    Abstract:

    Abstract Highly aligned arrays of ZnO/TiO2 core/shell nanorods were fabricated on glass substrates by hydrothermal growth of ZnO nanorods cores followed by the deposition of anatase TiO2 shells in a sol–gel process. The characterization of these composite materials with scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and transmission emission microscopy (TEM) points to the formation of crystalline ZnO nanorod cores that are coated with anatase TiO2 shells. Humidity sensors based on these core/shell nanorod arrays exhibit outstanding sensitivities with capacitances varying from 101 to 106 pF over a relative Humidity (RH) range of 11%–95% at room temperature, which is 1.5 and 3 orders of magnitude higher than that of pristine TiO2 films and ZnO nanorods, respectively. Complex impedance analysis indicated that the enhanced Humidity Sensitivity is probably due to the high surface/volume ratio of this core/shell material in combination with the remarkable hydrophilicity of the TiO2 shell.

  • Humidity sensors based on zno tio 2 core shell nanorod arrays with enhanced Sensitivity
    Gu L; Zheng K; Zhou Y; Li J; Mo X; Patzke Greta R; Chen G (2011). Humidity sensors based on ZnO TiO(2) core shell nanorod arrays with enhanced sensiti, 2011
    Co-Authors: Kaibo Zheng, Ying Zhou, Greta R Patzke, Guorong Chen
    Abstract:

    Highly aligned arrays of ZnO/TiO(2) core/shell nanorods were fabricated on glass substrates by hydrothermal growth of ZnO nanorods cores followed by the deposition of anatase TiO(2) shells in a sol-gel process. The characterization of these composite materials with scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and transmission emission microscopy (TEM) points to the formation of crystalline ZnO nanorod cores that are coated with anatase TiO(2) shells. Humidity sensors based on these core/shell nanorod arrays exhibit outstanding sensitivities with capacitances varying from 10(1) to 10(6) pF over a relative Humidity (RH) range of 11%-95% at room temperature, which is 1.5 and 3 orders of magnitude higher than that of pristine TiO(2) films and ZnO nanorods, respectively. Complex impedance analysis indicated that the enhanced Humidity Sensitivity is probably due to the high surface/volume ratio of this core/shell material in combination with the remarkable hydrophilicity of the TiO(2) shell. (C) 2011 Elsevier B.V. All rights reserved.

Jikui Luo - One of the best experts on this subject based on the ideXlab platform.

  • high Sensitivity flexible lamb wave Humidity sensors with a graphene oxide sensing layer
    Nanoscale, 2015
    Co-Authors: Weipeng Xuan, Jikui Luo, Jinkai Chen, Wenbo Wang, Xiaozhi Wang
    Abstract:

    This paper reports high performance flexible Lamb wave Humidity sensors with a graphene oxide sensing layer. The devices were fabricated on piezoelectric ZnO thin films deposited on flexible polyimide substrates. Two resonant peaks, namely the zero order antisymmetric (A0) and symmetric (S0) mode Lamb waves, were observed and fitted well with the theoretical analysis and modelling. With graphene oxide microflakes as the sensing layer, the sensing performance of both wave modes was investigated. The Humidity Sensitivity of the A0 mode is 145.83 ppm per %RH (at Humidity 85%RH), higher than that of S0 mode of 89.35 ppm per %RH. For the first time, we have demonstrated that the flexible Humidity sensors work as usual without noticeable deterioration in performance even under severe bending conditions up to 1500 μe. Also the sensors showed an excellent stability upon repeated bending for thousand times. All the results demonstrated that the Lamb wave flexible Humidity sensors have a great potential for application in flexible electronics.

  • engineering silver nanostructures for surface acoustic wave Humidity sensors Sensitivity enhancement
    Journal of The Electrochemical Society, 2014
    Co-Authors: Chao Zhao, Jikui Luo
    Abstract:

    In this paper, the Sensitivity of the LiNbO3 surface acoustic wave (SAW) based Humidity sensors has been enhanced with various nanostructured Ag materials, including thermally evaporated or chemically synthesized, and then thermally annealed ones. The results showed that the Humidity Sensitivity of the SAW devices increases with the surface roughness (porosity) of the sensing film, and can be further improved when Ag NPs are used. Smooth Ag film deposited by evaporation onto the SAW devices did not change the Humidity Sensitivity noticeably, but those with chemically deposited high porosity Ag films have a good Sensitivity of 80 kHz/75%RH. The SAW sensors with the Ag NPs have the highest Sensitivity up to about 800 kHz/75%RH, at least one order of magnitude higher than those reported before. The SAW sensors with Ag nano-particles showed a strong non-linearity, and explained by the different chemisorption capabilities of Ag and LiNbO3 surface.