88 Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B Volume 47 Number 2 April 2006 Paper presented at the American Ceramics Society Glass and Optical Ma- terials Division (GOMD) Fall Meeting and 14th International Symposium on Non-Oxide Glasses, Florida, USA. 7–12 November 2004. 1 Corresponding author. Email pieree@u.arizona.edu 1. Introduction Among all optical spectroscopy techniques, Fourier transform infrared (FTIR) is recognised as one of the most powerful tools for investigation of the structure of chemical and biological species. When a beam of infrared light interacts with a substance, a quantised amount of the light energy is absorbed to excite the fundamental vibrational modes that are unique to each molecule. The vibrational spectrum collected that way provides an infrared signature that is very specific to each chemical or biological species. It is also possible to perform these analyses remotely using infrared transparent glass fibres that can carry the signal to a sample and back to a detector. In this technique, the infrared source light interacts with the sample using the evanescent wave that extends beyond the surface of the glass fibre in a way very similar to an Attenuated Total Reflection (ATR) experiment. In the present study, a single TeAsSe chalcogenide fibre is employed as both a sensor and transmission line for the optical signal. The transparency domain of these fibres, from 2–13 μm, is particularly arac- tive and corresponds to a ‘fingerprint’ region where strong fundamental vibrational modes of organic molecules lie. This enables the quantitative analyses of chemical and biological species. (1,2) More recently, the fibre evanescent wave spectroscopy (FEWS) technique has been applied to the field of biomedi- cal analysis to monitor the metabolic activity of live microorganism. (3–5) This enables the design of cell- based bio-optic sensors where the ‘health’ of live cells is monitored spectroscopically and their response to minute amounts of environmental toxicants can be detected. Spectral features from the fingerprint region between 400–4000 cm −1 can supply information about the metabolic activity of the cell and allow the detection of small amounts of toxic agents that would otherwise be invisible by FTIR. (4) Spectroscopic properties of chalcogenide fibres for biosensor applications Pierre Lucas, 1 Michelle. A. Solis, Christophe Juncker Department of Material Science and Engineering, University of Arizona, Tucson, AZ 85721, USA David Le Coq Laboratoire de physicochimie de l'atmosphère, Universite du Lioral, 59140 Dunkerque, France Mark R. Riley, Jayne Collier, Dianne E. Boeseweer Department of Agricultural and Biosystems Engineering, University of Arizona, Tucson, AZ 85721, USA Catherine Boussard-Plédel & Bruno Bureau Laboratoire des Verres et Céramiques, UMR-CNRS 6512, Université de Rennes 1 Campus de Beaulieu, 35042 Rennes, France The spectroscopic characteristics of Te 2 As 3 Se 5 infrared optical fibres are investigated. Fibres with a diameter of approxi- mately 400 μm are tapered to produce a sensitive sensing zone and used as both a sensor and transmission line of the infrared optical signal in evanescent wave spectroscopy experiments. The fibre surface is shown to be hydrophobic, which results in enhanced detection sensitivity for nonpolar organic species in aqueous media. The peak intensity of organic species increases systematically relative to the peak intensity of water during a comparison of fibre and transmission spectroscopy experiments. A bio-optical sensor is developed by coating the fibre with human lung cells at the surface of the sensing zone. The metabolic activity of the cell is monitored spectroscopically and it is shown that the evanescent wave can locally probe the cell membrane integrity. During exposure to Triton X-100, the cell membrane signal shows a sharp decay in response to the surfactant. The ratio of methyl and methylene vibrations from membrane lipids decreases rapidly and provides a sensitive probe of the cell membrane integrity. This experiment demonstrates the capability of these fibre based bio-optic sensors to detect micromolar amounts of environmental toxicant. Phys. Chem. Glasses: Eur. J. Glass Sci. Technol. B, April 2006, 47 (2), 88–91