I. Ayerdi

System Requirement Analysis of Laser Interference Nanolithography

This paper presents a system requirement analysis of multi-beam laser interference nanolithography for nanoscale structuring of materials including seven sections: introduction, formation of multi-beam laser interference patterns, user requirements, system architecture, experiments, discussions and conclusions. Analytical expressions were obtained for the spatial distribution of radiation of the interfering beams as a function of their amplitudes, phases, angles of incidence on the sample, and polarization planes with computer simulation and experimental results. The environmental effect and technological potential were also discussed.

ZnO conductometric sensor for indoor air quality measurement inside buildings

The objective of this work is to develop a ZnO conductometric gas sensor to monitor two key pollutants in indoor environments: benzene and formaldehyde. Conductometric sensors are widely used for this purpose. The final aim of the sensor is to be integrated in an air quality measuring system connected to the HVAC (Heat Ventilation and Air Conditioning) system so that ventilation is activated according to the air quality within the building. As there is no EU common legislation about the target gases and detection limits, the authors have set them according to the recommendations of different agencies in Europe and the US.

Interference lithography processes with high-power laser pulses

Laser interference lithography (LIL) is concerned with the use of interference patterns generated from two or several coherent beams of laser radiation for the structuring of materials. This paper presents the work on the processes based on resists and direct writing with laser interference lithography. In the work, a four-beam laser interference system was used as a submicrometer structuring tool in which a high-energy pulsed, frequency-tripled and TM polarized Nd:YAG laser (355 nm) with a coherent length of 3 m, energy power up to 320 mJ/cm2, pulse duration of 8 ns and 10 Hz repetition rate was used as a light source. The experimental results were achieved with 2-beam and 4-beam interference patterning. The processes can be used to define submicron surface relieves in large areas for use in the field of MEMS.

Multisensor platform for indoor air quality measurements

The objective of this work is to develop a platform for a set of three conductometric sensors, able to deliver a controlled flow of indoor air samples in parallel to the three sensors. The system controls, on one hand, the air flow and, on the other hand, adds the capability of humidity control in two different ways: measuring humidity at the input and output, and stabilizing it through a filtering material. This way the performance of conductometric sensors can be enhanced, because one of the main causes of their low specificity is the cross-sensitivity to ambient humidity. The controlled amount of gas arriving at the sensors also avoids possible fluctuations in the sensor signals due to the air flow variations.

Fabrication and characterization of flexible flat electrodes for biomedical microdevices

Flat electrode arrays satisfy manifold biomedical applications. In this work, platinum flat electrodes sandwiched between two flexible PDMS layers are fabricated and characterized. A contact profilometer and a FIB/FEGSEM system are used for samples topology characterization. Electrical characterization covers I/V curves and stability tests. Platinum wavy surface reinforces the achieved samples compliance and therefore their suitability for human implant applications. However, the Pt electrical performance is strongly conditioned on the elastic PDMS layers. Fabrication process must be optimized to achieve a trade-off between mechanical and electrical behavior.

Topological and Electrical Analysis of Flexible Platinum Electrodes on Biocompatible PDMS Substrates

Electrode arrays satisfy manifold biomedical applications. In this work, platinum flat electrodes sandwiched between two flexible PolyDiMethylSiloxane (PDMS) layers are fabricated and characterized. A contact profilometer and an FIB/FEGSEM system are used for topology analysis. Electrical characterization covers I/V curves and stability tests. The wavy surface of Pt thin film reinforces the samples compliance and therefore their suitability for human implant applications. However, its electrical performance is strongly conditioned on the elastic PDMS layers. Fabrication process must be optimized to achieve a trade-off between mechanical and electrical behavior.