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A label-free compact method for performing photonic characterization of "healthy" versus "diseased" arteries has been developed. It permits the detection of atherosclerotic lesion in living mouse arteries. Using this prototype, we observed that the spectral response (photonic fingerprint, PIN) obtained from aortas of wild-type mice differs from the response of ApoE-KO mice fed with high-fat diet (an atheroprone mouse model). Benchmark of the results against gold standard was performed by staining the aortas with Oil-Red-O to visualize atherosclerotic plaques.

The LiPhos project (EU FP7 Grant Agreement No.: 317916, www.liphos.eu) aims to develop three different biophotonic diagnosis tools (BDTs), based on living photonics, namely: single layer living photonics (SLLP), single cell analysis (SCA); and multi-layer living photonics (MLLP). By Measuring of what we term the Photonic Fingerprint (or PIN), of the cells in such BDTs, should make it is possible to differentiate between healthy and non-healthy cell or tissue states. Moreover, the effect of specific drugs and pro-inflammatory agents could be assessed. This concept is currently being applied to the diagnosis of cardiovascular diseases (CVD).

In this paper two different photonic lab-on-a-chip devices for real-time cell screening are presented. We discuss, in parallel, screening of cell viability and cell count using a multiple total internal reflection (MIR) system, and a microbioreactor (MBR) for continuous cell culture screening. Each device takes advantage, in different ways, of the enhanced light-analyte interaction provided by the full-field approach. Their performance and how they represent an improvement to current methods, are also discussed herein. Both devices integrate photonic components and are fabricated by soft lithography (PDMS) replica molding of SU-8 masters, thus making them low-cost and easily mass produced.

The design, simulation, fabrication and characterization of two SU-8 based microoptoelectromechanical systems (MOEMS) are presented in this paper: an optical accelerometer and a variable optical attenuator (VOA). Both devices consist on a quad-beam polymer structure and can be fabricated with a simple technology, requiring only two photolithographic steps. In order to overcome the fibre optics positioning, self-alignment structures have been integrated on the devices. Working principle of both devices is based in the modulation of the optical losses (when an acceleration or voltage is applied at the accelerometer or the VOA, respectively). In order to achieve the optimal behaviour, several quad beam configurations have been studied by means of mechanical and optical simulations. An optical sensitivity of 16.58 dB/g has been estimated for the optimal configuration of the accelerometer. The experimental results show a good agreement, with measured optical sensitivities of 13.1 dB/g and 17.5 dB/g for negative and positive accelerations, respectively. On the other hand, the VOA has been electrothermally actuated, taking advantage of the high thermal expansion coefficient (CTE) of the SU-8, to achieve high optical attenuation (20 dB) with low power consumption (12mW).

Multimode interference devices based on silicon hollow waveguides have been designed, simulated, fabricated and characterized. Adequate confinement of light into a hollow waveguide and minimization of the propagation losses require a roughness of the structure below the working wavelength. This assures to have mirror behavior at the facets that optimize the Fresnel reflections. In order to achieve this low roughness and a perfectly vertical walls, to obtain a rectangular shape, an optimization of the fabrication process, especially deep reactive ion etching process, has been made. The numerical and experimental anti-symmetrical behavior for symmetrical and anti-symmetrical out waveguides in anti-symmetrical multimode interference devices is in accordance with the theory of multimode interference effects. The excellent behavior and properties of these devices shows the silicon hollow waveguides excellent for the design of integrated optical devices.

The characterization and optimization of a quad beam all-polymer optical accelerometer is presented in this paper. The working principle is based in the intensity modulation, due to the misalignment between three waveguides when acceleration is applied. Analytical, mechanical and optical simulations predict a high sensitivity of the proposed devices. Optimization of both the seismic mass/mechanical beams joint and the sacrificial layer are also presented. Experimental results shows an optical sensitivity of at least 15.8 dB/g, with an asymmetrical behavior attributable to a small misalignment between the waveguides when no acceleration is applied.

Basic steps involved in the fabrication of integrated optical elements will be presented. Emphasis will be put on the development steps required to establish an Integrated Optical Technology based on silicon, which includes from the definition of the waveguide structure to the fabrication and characterization procedures. Aspects such as the numerical simulation of the components, the design of the optical element suitable as sensor, the analysis of the light input coupling methods, and the process parameters fitting according to the required materials will be highlighted in this paper. Finally, two examples will be presented, show its applicability of the developed technological steps. An "optode," or optical absorption sensor, suitable for the measurement of chemical concentration of a given ion in solution, due to modulation of the complex part of the refractive index (RI), and a biosensor based on the coupling efficiency of an optical waveguide cantilever.

Silicon oxide films are deposited on silicon wafers by PECVD from SiH4 and N2O at different values of the deposition parameters. The refractive index is found to vary with gas flow ratio (R), making these films suitable for a silicon-based integrated optics technology. The films are submitted to annealing processes on inert atmosphere in order to facilitate the impurity effusion, thus reducing the light transmission losses. However, relying upon deposition conditions, this process significantly changes the film stress and often affects the film integrity. In this work a study of the evolution of mechanical stress under different annealing conditions is carried out for silicon oxide PECVD- films. All as-deposited samples exhibit compressive stress. During thermal cycles up to 300 degree(s)C a different behavior of the mechanical stress is obtained depending on the deposition parameters. For R at about 20 a significant stress hysteresis is observed at low deposition temperatures. For R at about 5 no hysteresis is observed at any deposition temperature. After a subsequent RTA a drastic and opposite variation of the stress is observed for the two kind of films and a very stable material from the mechanical point of view, is obtained. An insight into the physical causes of these behaviors is presented.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.