Optical fibre sensors based on vapochromic gold complexes for environmental applications

Abstract A new vapochromic material based on a gold–silver complex and diphenylacetyl, of formula [Au2Ag2(C6F5)4(C6H5C CC6H5)], has been developed and used for the detection of some volatile organic compounds (VOCs). The material is presented in the form of dark green powders. When the powders are in presence of VOC, its colour changes, yielding to a change in its optical properties. The sensor consists of an optical fibre pigtail onto the cleaved end of which the vapochromic material was deposited. The fibre has a core diameter of 200 μm and a plastic cladding. A commercially available solvent, Liquicoatc is used to create a solution, capable of being fixed onto the fibre. The fibre optic sensor is employed in a reflection scheme, so the other extreme of the optical fibre pigtail is connected to an optical coupler, completing the set-up with an optical source to generate the interrogating signal and an optical detector to measure the received intensity-modulated signal. The behavior of the sensor has been studied for different wavelengths for different concentrations of several VOC. Changes up to 2.5 dB in the reflected optical power were detected.

[1]  K. R. Mann,et al.  Synthesis and characterization of Pt(CN-p-(C(2)H(5))C(6)H(4))(2)(CN)(2), a crystalline vapoluminescent compound that detects vapor-phase aromatic hydrocarbons. , 2002, Journal of the American Chemical Society.

[2]  Kenneth T. V. Grattan,et al.  Fiber optic sensor technology: an overview , 2000 .

[3]  Nathan S. Lewis,et al.  Array-based vapor sensing using chemically sensitive, carbon black-Polymer resistors , 1996 .

[4]  Ignacio R. Matias,et al.  Detection of volatile organic compound vapors by using a vapochromic material on a tapered optical fiber , 2000 .

[5]  Jay W. Grate,et al.  Method for unknown vapor characterization and classification using a multivariate sorption detector. Initial derivation and modeling based on polymer-coated acoustic wave sensor arrays and linear solvation energy relationships , 1999 .

[6]  Carlos Fernández-Valdivielso,et al.  An experimental study about the utilization of Liquicoat® solutions for the fabrication of pH optical fiber sensors , 2002 .

[7]  S. Iraj Najafi,et al.  Optical and mechanical characterization of spin-on deposited silicon and titanium dioxide films , 1990, Optics & Photonics.

[8]  Kent R. Mann,et al.  Structural Investigations of Vapochromic Behavior. X-ray Single-Crystal and Powder Diffraction Studies of [Pt(CN-iso-C3H7)4][M(CN)4] for M = Pt or Pd , 1998 .

[9]  G. Sheldrick,et al.  Synthesis and reactivity of bimetallic Au–Ag complexes. X-Ray structure of a chain polymer containing the moiety…(F5C6)2Au(µ-AgSC4H8)2Au(C6F5)2… , 1981 .

[10]  S. Najafi,et al.  Sol-gel glass waveguides with Bragg grating , 1998 .

[11]  Carlos Fernández-Valdivielso,et al.  Optical fiber sensor based on lutetium bisphthalocyanine for the detection of gases using standard telecommunication wavelengths , 2003 .

[12]  K. R. Mann,et al.  A Vapochromic LED , 1998 .

[13]  Hanns-Erik Endres,et al.  A capacitive CO2 sensor system with suppression of the humidity interference , 1999 .

[14]  Mariano Laguna,et al.  Synthesis and reactivity of bimetallic Au–Ag polyfluorophenyl complexes; crystal and molecular structures of [{AuAg(C6F5)2(SC4H8)}n] and [{AuAg(C6F5)2(C6H6)}n] , 1984 .

[15]  G. Koten,et al.  Organoplatinum crystals for gas-triggered switches , 2000, Nature.

[16]  V. Yam,et al.  Solvent-induced aggregation through metal...metal/pi...pi interactions: large solvatochromism of luminescent organoplatinum(II) terpyridyl complexes. , 2002, Journal of the American Chemical Society.

[17]  Gilles Delapierre,et al.  Polymer-based capacitive humidity sensor: characteristics and experimental results , 1983 .

[18]  David Levy,et al.  Photochromic Sol−Gel Materials , 1997 .

[19]  K. R. Mann,et al.  Characterization of a cross-reactive electronic nose with vapoluminescent array elements. , 2002, Analytical chemistry.

[20]  Jay W. Grate,et al.  Steplike Response Behavior of a New Vapochromic Platinum Complex Observed with Simultaneous Acoustic Wave Sensor and Optical Reflectance Measurements , 2002 .

[21]  C. Wan,et al.  Sol–gel processed TiO2–K2O–LiZnVO4 ceramic thin films as innovative humidity sensors , 2000 .

[22]  Colette McDonagh,et al.  Sol-gel coatings for optical chemical sensors and biosensors , 1995 .

[23]  J. Grate,et al.  Comparisons of polymer/gas partition coefficients calculated from responses of thickness shear mode and surface acoustic wave vapor sensors. , 1998, Analytical chemistry.

[24]  K. R. Mann,et al.  Infrared Spectroscopy Studies of Platinum Salts Containing Tetracyanoplatinate(II). Evidence for Strong Hydrogen-Bonding Interactions in “Vapochromic” Environmental Sensor Materials , 1998 .

[25]  Gossage,et al.  Diagnostic organometallic and metallodendritic materials for SO2 gas detection: reversible binding of sulfur dioxide to arylplatinum(II) complexes , 2000, Chemistry.

[26]  I. Matías,et al.  Behavioral experimental studies of a novel vapochromic material towards development of optical fiber organic compounds sensor , 2001 .