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Balda R.,Escuela Superior de Ingenieria | Balda R.,Donostia International Physics Center | Pena J.I.,University of Zaragoza | Angeles Arriandiaga M.,University of the Basque Country | And 2 more authors.
Optics Express | Year: 2010

In this work we report the study of energy transfer between Nd3+ and Yb3+ions in glasses with the 0.8CaSiO3-0.2Ca 3(PO4)2 eutectic composition at room temperature by using steady-state and time-resolved laser spectroscopy. The Nd3+ Yb3+ transfer efficiency obtained from the Nd 3+ lifetimes in the single doped and codoped samples reaches 73% for the highest Nd3+ concentration. The donor decay curves obtained under pulsed excitation have been used to establish the multipolar nature of the Nd3+ Yb3+ transfer process and the energy transfer microparameter. The nonradiative energy transfer is consistent with an electric dipole-dipole interaction mechanism assisted by energy migration among donors. Back transfer from Yb3+ to Nd3+ is also observed. ©2010 Optical Society of America.


Balda R.,Escuela Superior de Ingenieria | Balda R.,Donostia International Physics Center | Al-Saleh M.,Escuela Superior de Ingenieria | Arriandiaga M.A.,University of the Basque Country | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

In this work, we report the upconversion emission from Pr3+ and Nd3+ ions in potassium lead chloride crystal KPb2Cl 5after excitation in the 4F5/2,3/2 levels of Nd3+ ions. We have observed violet, blue, green, orange, and red emissions at room temperature. Blue emission from Pr3+ ions is induced by near infrared laser excitation of Nd3+ through energy transfer from Nd3+ to Pr3+ ions. The mechanisms leading to the visible emissions have been investigated by studying the dependence of the upconversion luminescence on the excitation wavelength and intensity of the IR pump light. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).


Balda R.,Escuela Superior de Ingenieria | Balda R.,Donostia International Physics Center | Al-Saleh M.,Escuela Superior de Ingenieria | Miguel A.,Escuela Superior de Ingenieria | And 3 more authors.
Optical Materials | Year: 2011

In this work we report the optical properties and upconversion luminescence of Er3+ ions in TeO2-WO3-PbO-BaF2 and TeO2-TiO2-Nb2O5-BaF2 fluorotellurite glasses and their comparison with those of TeO 2-TiO2-Nb2O5 glass. The optical properties of Er3+ ions have been established in terms of absorption and emission spectra and lifetime measurements. The 1.5 μm emission cross-section has been determined from the line shape of the emission spectrum and the calculated emission probability for the 4I13/2 level. The highest emission cross section (6.9 × 10-21 cm 2) corresponds to the TeO2-TiO2-Nb 2O5-BaF2 glass with a figure of merit for the bandwidth of 524.4 cm2 nm. Upconversion emissions at 530, 548 nm, and 660 nm have been obtained under infrared excitation at 800 nm in the 4I9/2 level and compared with those obtained under one photon excitation. The green emission corresponding to the 4S 3/2 → 4I15/2 transition is dominant in all glasses. The excitation wavelength dependence of the upconverted luminescence together with its time evolution after infrared pulsed excitation suggest that energy transfer upconversion processes are responsible for the green upconversion luminescence. © 2011 Elsevier B.V. All rights reserved.


Perdigones F.,Escuela superior de ingenieria | Aracil C.,Escuela superior de ingenieria | Quero J.M.,Escuela superior de ingenieria | Gutierrez M.,CSIC - National Center of Microelectronics | And 2 more authors.
Microsystem Technologies | Year: 2014

In this paper, a method of integration of silicon sensors in microfluidic platform is presented. In particular, impedimetric silicon sensors are used to make the proof of concept. These sensors are integrated in a FR4 substrate [component of a printed circuit board (PCB)] where the SU-8 microfluidic circuit is built. In order to generalize the application of this method, standard processes that are typical in the laboratories are used. The material to fabricate those microfluidic circuits is the negative photoresist SU-8. The method of fabrication consists on performing the typical SU-8 process over the silicon chips once they are inserted in the FR4 substrate. This method must provide flatness to avoid irregular microchannels. Also, the proposed process must ensure the insulation of the electric connections to avoid short-circuits when the sample fluid flows through the systems, and bondings robust enough to support a spinning step. In addition, the SU-8 process must be clean enough to keep the capability of measurement of the sensors. This cleanness has been studied using different conductivities of a KCl solution, providing good results. Finally, apart from integrating microfluidic and electronics in the same substrate, this method of integration provides an approach to the optimum between low cost, simplicity and precise measurements thank to the use of inexpensive PCB-based platforms and precise silicon sensors. © 2014, Springer-Verlag Berlin Heidelberg.


Perdigones F.,Escuela Superior de Ingenieria | Luque A.,Escuela Superior de Ingenieria | Ganan-Calvo A.M.,Escuela Superior de Ingenieria | Quero J.M.,Escuela Superior de Ingenieria
Microsystem Technologies | Year: 2013

A bi-membrane structure is the main component of flow regulators for microfluidics with positive gain actuation. This microstructure is composed of two deformable circular membranes with different area tied by a rigid link that makes them move together. A comprehensive analysis of this microstructure is presented in this paper, which also provides an easy and practical design process in microsystems. The study is based on the microstructure behavior in typical microfluidic networks and is presented using dimensionless plots which have been obtained by numerical simulations based on finite element method performed by CoventorWare. The microstructure is defined using four dimensionless numbers for its seven dimensional parameters, and a dimensionless pressure. This fact represents the universal character of the design, dividing it into geometrical and material parts. The dimensionless pressure allows the use of any homogeneous and isotropic material in the design process of the devices. The values obtained from the plots are compared with simulation results using specific materials and dimensions and these comparisons present good agreement. Using the proposed analysis and design process, this sort of microstructures can be used by MEMS designers as standard components in microfluidic devices. © 2012 Springer-Verlag.

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