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Póster presentado a la 17th International Sol-Gel Conference. Madrid, 2013. In this work a novel camera phone system for fluorescence-based sol-gel-derived pH sensing is presented. The sol-gel based pH material, a microfluidic chip and a camera phone have been combined to obtain a fluorescence-based sensing system for fast and easy pH measurements. This work was supported by a UPNA Research Grant

The substitution of conventional bench-top instrumentation by fully integrated lab-on-chip systems continues to be a challenge. The integration of microfluidics and integrated optics in glass is an important step towards this goal, forming the focus of this work [1]. In particular, excitation and detection of fluorescence emitted by labeled biomolecules flowing through a microfluidic channel is considered. Excitation occurs at specific wavelengths by means of waveguides inscribed with femtosecond laser pulses in a commercial, glass lab-on-chip. A widely known diagnostic application that will exploit this sensing scheme is the monitoring of microchip capillary electrophoresis (MCE) leading to separation of DNA fragments of different lengths, labeled with fluorescent dye molecules. In order to meet the resolution demands of MCE separation and to achieve multi-point sensing, we envision a device consisting of on-chip integrated optical splitters written coplanar with the microfluidic channel along which MCE separation takes place.

Design issues of a spiral-shaped Mach-Zehnder interferometer are discussed.

In this work, we present a theoretically study on slow-light in ring-resonator circuits and discuss quantitatively its role in enhancing the sensor performance. The model is based on the transfer matrix method and the complex transmission coefficient approach, by assuming a homogeneous refractometric IO sensor with MZI read-out scheme. The modeling results show that using realistic structure parameters and a typical read-out capability, a refractive index detection limit of one order better than the present state of the art IO MZI sensing structure can be expected by the inclusion of such a slow-light structure. The realization of such device is under progress at the moment of the preparation of this abstract. The device will be based on Si3N4 IO technologies with a serrodyne phase readout scheme employing a ZnO electro-optical modulator. The latest results of the realization and experimental progress will be reported in the conference as well.

The paper reports on theoretical and experimental results of integrated optical (IO) cavities defined by grated waveguides in $Si_3N_4$ and Si, for the accurate detection of cantilever deflection and bulk index changes.

Copper(I) and copper(II) complexes of two bis(oxazolinyl)pyridines were immobilized on silica via electrostatic interactions. The catalytic activity of the immobilized catalysts in the direct addition of terminal alkynes to imines leading to propargylamines was investigated under a variety of reaction conditions. The performance of the immobilized catalysts compares very well with their homogeneous equivalents. When used in toluene, the catalysts could be recycled a number of times and maintained activity. This study is the first such report of the immobilization on silica in this manner of any bis(oxazolinyl)pyridine (pybox) complex

An optical sensor for the measurement of carbon dioxide in Modified Atmosphere Packaging (MAP) applications has been developed. It is based on the fluorescent pH indicator 1-hydroxypyrene-3,6,8-trisulfonate (HPTS) immobilised in a hydrophobic organically modified silica (ormosil) matrix. Cetyltrimethylammonium hydroxide was used as an internal buffer system. Fluorescence is measured in the phase domain by means of the Dual Luminophore Referencing (DLR) sensing scheme which provides many of the advantages of lifetime-based fluorometric sensors and makes it compatible with established optical oxygen sensor technology. The long-term stability of the sensor membranes has been investigated. The sensor displays 13.5 degrees phase shift between 0 and 100% CO2 with a resolution of better than 1% and a limit of detection of 0.08%. Oxygen cross-sensitivity is minimised (0.6% quenching in air) by immobilising the reference luminophore in polymer nano-beads. Cross-sensitivity towards chloride and pH was found to be negligible. Temperature effects were studied, and a linear Arrhenius correlation between ln k and 1/T was found. The sensor is stable over a period of at least seven months and its output is in excellent agreement with a standard reference method for carbon dioxide analysis.