Andreu Llobera

Opto-thermal actuation in double layer polymer microcantilevers

Photostructurable polymers, such as SU-8, have large potential impact on the field of MEMS/NEMS, allowing simple fabrication of plastic MEMS/NEMS devices with nearly vertical sidewalls and high aspect ratios using standard photolithographic procedures. Functional properties (as electrical conductivity or photoluminiscence) can be added to a photostructurable polymer by doping the material with nanoparticles and/or nanocrystals. We present here the case in which the resulting material presents opto-thermal properties if it is combined with an undoped polymer. From all the different mechanisms for heating the structure, opto-thermal actuation is interesting from the point of view that it is possible to obtain a mechanical energy transduction without requiring physical contact or proximity interaction, i.e. devices can be moved merely by focusing light on it.

Characterization of antiresonant reflecting optical waveguide devices by scanning near-field optical microscopy

Silicon-based antiresonant reflecting optical waveguide (ARROW) devices were studied by means of a scanning near-field optical microscope. Various structures such as a Y junction of a Mach-Zehnder interferometer and a directional optical coupler were characterized, showing the propagation of the light inside the devices simultaneously with the topography. Scattering on the splitting point of the Y junction was shown, as well as a partial coupling of the light between the two branches of the coupler. Measurements on the decay length of the evanescent field were also performed to study the use of the ARROW waveguide for sensor purposes.

Poly(dimethylsiloxane) photonic microbioreactors and multiple internal reflection systems for real time cell screening

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.

Hollow waveguides ray-tracing analysis

A ray tracing simulation method for integrated optics hollow waveguides has been developed. This method has been tested on Silicon waveguides with good results, providing a suitable design tool for new devices using this type of waveguides. The simulations allow the design of new guiding structures based on hollow waveguides, like input tapers to reduce the insertion losses. The study of the hollow waveguide behavior with different refractive indices opens the way for their use as refractive index sensors.