Papers by Author: L. Rebouta

Abstract: Magnetostrictive thin films of the ternary compound (Tb_yDy_1-y)xFe_1-x have been prepared by magnetron sputtering from a Terfenol D target onto both room-temperature and high-temperature substrates (T_S<550 °C). The aim is to select the deposition parameters of this highly magnetostrictive material in order to optimize its magnetic response. Films prepared on room-temperature substrates were amorphous and those deposited at high temperatures have a microstructure consisting of small grains of RFe₂ compound and some RE oxide phases. Deposition temperatures around 550 °C promotes in-plane orientation of (220) and (311) planes of RFe₂ phase. The magnetization measurements performed at room temperature showed that depending on the processing conditions the material changes from a soft magnetic behavior with perpendicular anisotropy to a two phase system with both hard and soft magnetic phases.

Abstract: This paper describes a fully-integrated lab-on-a-chip device for testing and monitoring biochemical parameters in biological fluids. The major innovation of this microdevice is the application of an acoustic microagitation technique with automatic electronic control based on a β-PVDF piezoelectric polymer placed underneath the microfluidic structures. Experimental results regarding the influence of the thickness of the polymer on the reaction rate of biological fluids are presented. Moreover, the study of the transmittance curve of β-PVDF with transparent conductive electrodes is also presented. Transparent electrodes are a constraint once the polymer is incorporate underneath the reaction chamber due to the analytical measurement by spectrophotometry.

Abstract: Transparent conducting Al doped ZnO films have been deposited by dc magnetron sputtering on glass and polymer substrates at room temperature. Depositions have been carried out from an AZOY (contains a small amount of Y2O3 in addition to Al2O3 and ZnO) target under different conditions such as working pressure, substrate bias voltage and oxygen flow rate. The crystallinity of the Al doped ZnO films has been improved by using low-energy-ion bombardment. Likewise, the use of either the rotation or the static mode of the substrate during deposition influences the crystallinity and therefore the optical parameters and the electrical resistance of the films. Increasing the thickness of the films reduces the threshold strain at which the films can be deformed without provoking significant changes on their electrical properties.