The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Limin Tong - One of the best experts on this subject based on the ideXlab platform.

  • micro nanofibre Optical Sensors challenges and prospects
    Sensors, 2018
    Co-Authors: Limin Tong
    Abstract:

    Micro/nanofibres (MNFs) are Optical fibres with diameters close to or below the vacuum wavelength of visible or near-infrared light. Due to its wavelength- or sub-wavelength scale diameter and relatively large index contrast between the core and cladding, an MNF can offer engineerable waveguiding properties including Optical confinement, fractional evanescent fields and surface intensity, which is very attractive to Optical sensing on the micro and nanometer scale. In particular, the waveguided low-loss tightly confined large fractional evanescent fields, enabled by atomic level surface roughness and extraordinary geometric and material uniformity in a glass MNF, is one of its most prominent merits in realizing Optical sensing with high sensitivity and great versatility. Meanwhile, the mesoporous matrix and small diameter of a polymer MNF, make it an excellent host fibre for functional materials for fast-response Optical sensing. In this tutorial, we first introduce the basics of MNF optics and MNF Optical Sensors, and review the progress and current status of this field. Then, we discuss challenges and prospects of MNF Sensors to some extent, with several clues for future studies. Finally, we conclude with a brief outlook for MNF Optical Sensors.

  • Microfiber Optical Sensors: A Review
    Sensors, 2014
    Co-Authors: Jingyi Lou, Yipei Wang, Limin Tong
    Abstract:

    With diameter close to or below the wavelength of guided light and high index contrast between the fiber core and the surrounding, an Optical microfiber shows a variety of interesting waveguiding properties, including widely tailorable Optical confinement, evanescent fields and waveguide dispersion. Among various microfiber applications, Optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic Sensors with small footprint, high sensitivity, fast response, high flexibility and low Optical power consumption. Here we review recent progress in microfiber Optical Sensors regarding their fabrication, waveguide properties and sensing applications. Typical microfiber-based sensing structures, including biconical tapers, Optical gratings, circular cavities, Mach-Zehnder interferometers and functionally coated/doped microfibers, are summarized. Categorized by sensing structures, microfiber Optical Sensors for refractive index, concentration, temperature, humidity, strain and current measurement in gas or liquid environments are reviewed. Finally, we conclude with an outlook for challenges and opportunities of microfiber Optical Sensors.

  • photonic nanowires from subwavelength waveguides to Optical Sensors
    Accounts of Chemical Research, 2014
    Co-Authors: Xin Guo, Yibin Ying, Limin Tong
    Abstract:

    Nanowires are one-dimensional (1D) nanostructures with comparatively large aspect ratios, which can be useful in manipulating electrons, photons, plasmons, phonons, and atoms for numerous technologies. Among various nanostructures for low-dimensional photonics, the 1D nanowire is of great importance owing to its ability to route tightly confined light fields in single-mode with lowest space and material requirements, minimized Optical path, and high mechanical flexibilities. In recent years, nanowire photonics have increasingly been attracting scientists’ interests for both fundamental studies and technological applications because 1D nanowires have more favorable properties than many other structures, such as 0D quantum dots (QDs) and 2D films.As subwavelength waveguides, free-standing nanowires fabricated by either chemical growth or physical drawing techniques surpass nanowaveguides fabricated by almost all other means in terms of sidewall smoothness and diameter uniformity. This conveys their low wave...

  • Polymer single-nanowire Optical Sensors
    Nano Letters, 2008
    Co-Authors: Fuxing Gu, Xuefeng Yin, Lei Zhang, Limin Tong
    Abstract:

    We report highly versatile nanoSensors using polymer single nanowires. On the basis of the Optical response of waveguiding polymer single nanowires when exposed to specimens, functionalized polymer nanowires are used for humidity sensing with a response time of 30 ms and for NO 2 and NH 3 detection down to subparts-per-million level. The compact and flexible sensing scheme shown here may be attractive for very fast detection in physical, chemical, and biological applications with high sensitivity and small footprint.

Peidong Yang - One of the best experts on this subject based on the ideXlab platform.

  • multifunctional nanowire evanescent wave Optical Sensors
    Advanced Materials, 2007
    Co-Authors: Donald J Sirbuly, Peidong Yang
    Abstract:

    Compact, reusable chemical Sensors are highly desirable for on-site detection in the field, including the identification of water contaminants, hazardous biochemical compounds, or blood serum content. Ideally, such a sensing platform should be portable, and employ several complementary sensing modalities that allow quantitative chemical identification of extremely small sample volumes. Optical spectroscopy is a powerful analytical tool for characterizing biological and chemical systems, but making a standard Optical laboratory transportable is a major challenge. However, with recent advances in the synthesis and assembly of nanomaterials, [1] it is timely to begin integrating these materials into functional device architectures for sensing and monitoring. Of the well-studied inorganic nanostructures, chemically synthesized 1D semiconductor systems have gained significant interest from the photonics community as passive and active components for miniaturized spectroscopic devices. This is due, in part, to their ability to guide a significant portion of the confined electromagnetic energy outside the measurement cavity (i.e., in the evanescent field) while operating below the diffraction limit of light. [2] Because the evanescent field efficiently travels through fluidic and air dielectrics, [3] it is possible to integrate the waveguides into microfluidic devices and sense molecules located near the surface of the cavity. We demonstrate this by performing absorbance, fluorescence, and surface-enhanced Raman spectroscopy (SERS) measurements on sub-picoliter volumes of solution. The chemical specificity of SERS is obtained by decorating the waveguide with silver nanocubes, thus enhancing the field around the nanoribbon. Our nanowire Optical sensing platform complements nanowire field-effect Sensors [4] with the ability to monitor Optical attenuation across the wire element. However, the use of photons instead of electrons allows Optical spectroscopy to be carried out on the analyte. Fiber-based detection is a unique alternative to free-space sensing, because it localizes chemical recognition at the surface of a waveguide. Among the most popular sensing schemes that rely on the evanescent field of a fiber are absorption [5–7] and fluorescence. [8–11] Typically, these set-ups involve multimode silica fibers with diameters much larger than the free-space wavelength of light. The evanescent field in these experiments has been used to measure refractive indices of liquids, [12] monitor volatile compounds in water, [13] and detect shifts in localized surface-plasmon resonances of coupled metal colloids. [14] Recently, the use of subwavelength silica fibers in a Mach–Zehnder-type interferometer to detect index changes caused by molecules interacting with the surface of the fibers has been proposed. [15] Although these various sensing configurations are promising for high sensitivity, fast cycling times, and reversibility, they do not provide versatility in their spectroscopic detection, nor enable a chemical read-out of the analyte. To move beyond fiber Sensors that operate solely as on/off detectors it is vital to develop materials that can sustain multiple analytical modes for chemical identification.

Donald J Sirbuly - One of the best experts on this subject based on the ideXlab platform.

  • multifunctional nanowire evanescent wave Optical Sensors
    Advanced Materials, 2007
    Co-Authors: Donald J Sirbuly, Peidong Yang
    Abstract:

    Compact, reusable chemical Sensors are highly desirable for on-site detection in the field, including the identification of water contaminants, hazardous biochemical compounds, or blood serum content. Ideally, such a sensing platform should be portable, and employ several complementary sensing modalities that allow quantitative chemical identification of extremely small sample volumes. Optical spectroscopy is a powerful analytical tool for characterizing biological and chemical systems, but making a standard Optical laboratory transportable is a major challenge. However, with recent advances in the synthesis and assembly of nanomaterials, [1] it is timely to begin integrating these materials into functional device architectures for sensing and monitoring. Of the well-studied inorganic nanostructures, chemically synthesized 1D semiconductor systems have gained significant interest from the photonics community as passive and active components for miniaturized spectroscopic devices. This is due, in part, to their ability to guide a significant portion of the confined electromagnetic energy outside the measurement cavity (i.e., in the evanescent field) while operating below the diffraction limit of light. [2] Because the evanescent field efficiently travels through fluidic and air dielectrics, [3] it is possible to integrate the waveguides into microfluidic devices and sense molecules located near the surface of the cavity. We demonstrate this by performing absorbance, fluorescence, and surface-enhanced Raman spectroscopy (SERS) measurements on sub-picoliter volumes of solution. The chemical specificity of SERS is obtained by decorating the waveguide with silver nanocubes, thus enhancing the field around the nanoribbon. Our nanowire Optical sensing platform complements nanowire field-effect Sensors [4] with the ability to monitor Optical attenuation across the wire element. However, the use of photons instead of electrons allows Optical spectroscopy to be carried out on the analyte. Fiber-based detection is a unique alternative to free-space sensing, because it localizes chemical recognition at the surface of a waveguide. Among the most popular sensing schemes that rely on the evanescent field of a fiber are absorption [5–7] and fluorescence. [8–11] Typically, these set-ups involve multimode silica fibers with diameters much larger than the free-space wavelength of light. The evanescent field in these experiments has been used to measure refractive indices of liquids, [12] monitor volatile compounds in water, [13] and detect shifts in localized surface-plasmon resonances of coupled metal colloids. [14] Recently, the use of subwavelength silica fibers in a Mach–Zehnder-type interferometer to detect index changes caused by molecules interacting with the surface of the fibers has been proposed. [15] Although these various sensing configurations are promising for high sensitivity, fast cycling times, and reversibility, they do not provide versatility in their spectroscopic detection, nor enable a chemical read-out of the analyte. To move beyond fiber Sensors that operate solely as on/off detectors it is vital to develop materials that can sustain multiple analytical modes for chemical identification.

Lúcia Bilro - One of the best experts on this subject based on the ideXlab platform.

  • Optical Sensors based on plastic fibers
    Sensors (Switzerland), 2012
    Co-Authors: Lúcia Bilro, Nelia Alberto, João L. Pinto, Rogério Nogueira
    Abstract:

    The recent advances of polymer technology allowed the introduction of plastic Optical fiber in sensor design. The advantages of Optical metrology with plastic Optical fiber have attracted the attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic Optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented.

  • Optical Sensors based on fiber bragg gratings for structural health monitoring
    New Developments in Sensing Technology for Structural Health Monitoring, 2011
    Co-Authors: Paulo Antunes, P Pinto, Nelia Alberto, Rogerio N Nogueira, J.l. Pinto, Hugo Rodrigues, Aníbal Costa, H Lima, Lúcia Bilro, Humberto Varum
    Abstract:

    In this work we review the structural health monitoring techniques based on fiber Bragg gratings. The working principle of the fiber Bragg gratings Sensors and the most common techniques to inscribe and interrogate these Sensors are described. Several implemented examples are also presented, like the deformation monitoring of one historical building with reduced visual impact, the unidirectional acceleration measurements in a metallic bridge structure and the bidirectional acceleration monitoring in a 50 m mobile telecom tower. Finally, the implementation of an automated remote structural health monitoring system design to operate with Optical Sensors in a highway bridge is described.

Francesco Michelotti - One of the best experts on this subject based on the ideXlab platform.

  • combining label free and fluorescence operation of bloch surface wave Optical Sensors
    Optics Letters, 2014
    Co-Authors: Alberto Sinibaldi, Antonio Fieramosca, Riccardo Rizzo, Aleksei Anopchenko, Norbert Danz, Peter Munzert, Claudio Magistris, Claudia Barolo, Francesco Michelotti
    Abstract:

    We report on the design, fabrication, and characterization of Optical Sensors based on Bloch surface waves propagating at the truncation edge of one-dimensional photonic crystals. The Sensors can be simultaneously operated in both a label-free mode, where small refractive index changes at the surface are detected, and a fluorescence mode, where the fluorescence from a novel heptamethyne dye label in the proximity of the surface is collected. The two modes operate in the near-infrared spectral range with the same configuration of the Optical reading apparatus. The limit of detection is shown to be smaller than that of equivalent surface plasmon Sensors and the fluorescence collection efficiency is such that it can be efficiently analyzed by the same camera sensor used for label-free operation.