Abstract
Microcystin-LR (MC-LR) is a dangerous toxin found in environmental waters, quantified by high performance liquid chromatography and/or enzyme-linked immunosorbent assays. Quick, low cost and on-site analysis is thus required to ensure human safety and wide screening programs. This work proposes label-free potentiometric sensors made of solid-contact electrodes coated with a surface imprinted polymer on the surface of Multi-Walled Carbon NanoTubes (CNTs) incorporated in a polyvinyl chloride membrane. The imprinting effect was checked by using non-imprinted materials. The MC-LR sensitive sensors were evaluated, characterized and applied successfully in spiked environmental waters. The presented method offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods. (C) 2012 Elsevier Ltd....Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.

Abstract
The present work reports new sensors for the direct determination of Microcystin-LR (MC-LR) in environmental waters. Both selective membrane and solid contact were optimized to ensure suitable analytical features in potentiometric transduction. The sensing layer consisted of Imprinted Sol-Gel (ISG) materials capable of establishing surface interactions with MC-LR. Non-Imprinted Sol-Gel (NISG) membranes were used as negative control. The effects of an ionic lipophilic additive, time of sol-gel polymerization, time of extraction of MC-LR from the sensitive layer, and pH were also studied. The solid contact was made of carbon, aluminium, titanium, copper or nickel/chromium alloys (80 : 20 or 90 : 10). The best ISG sensor had a carbon solid contact and displayed average slopes of 211.3 mV per decade, with detection limits of 7.3 x 10(-10) M, corresponding to 0.75 mu g L-1. It showed linear responses in the range of 7.7 x 10(-10) to 1.9 x 10(-9) M of MC-LR (corresponding to 0.77-2.00 mu g L-1), thus including the limiting value for MC-LR in waters (1.0 mu g L-1). The potentiometric-selectivity coefficients were assessed by the matched potential method for ionic species regularly found in waters up to their limiting levels. Chloride (Cl-) showed limited interference while aluminium (Al3+), ammonium (NH4+), magnesium (Mg2+), manganese (Mn2+), sodium (Na+), and sulfate (SO42-) were unable to cause the required potential change. Spiked solutions were tested with the proposed sensor. The relative errors and standard deviation obtained confirmed the accuracy and precision of the method. It also offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods.

Abstract
This article presents results of device fabrication using UV processing of materials and integrated optic components produced by flame hydrolysis deposition and hybrid sol-gel technology. Photosensitive materials were employed in the fabrication of channel waveguides and channel photo-imprinted waveguides incorporating Bragg gratings through single and double-step exposure.

Abstract
A single long-period fibre grating was written in a biconical fibre taper made from standard communications step-index optical fibre, resulting in an interferometric fibre sensor device that provided a resolution of 1 × 10-4 for refractive indices in the range of 1.30 to 1.34, suggesting that these devices may be suitable for use with aqueous solutions. © IEE 2005.

Abstract
In this paper, direct UV-laser writing was used to produce channel waveguides and diffraction gratings on thin films of siliceous-based organic-inorganic hybrid materials. The optical quality of the films surface was studied by light scattering measurements. The produced Y-power splitters, optical filters and Fabry-Perot cavities were experimentally characterized for propagation in the near infrared spectral region. © 2010 IEEE.

Abstract
Channel waveguides incorporating photo-imprinted Bragg gratings were produced in germano-borosilicate glass layers fabricated by flame hydrolysis deposition, through single-and double-step exposure direct writing processes with UV laser irradiation. To our knowledge, this is the first time that UV exposure has been used to simultaneously realize both waveguiding and spectral selectivity functions.