Romanian National Institute for Research and Development in Microtechnologies

Bucharest, Romania

Romanian National Institute for Research and Development in Microtechnologies

Bucharest, Romania
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Drechsel L.,Hsg Imit Institute For Mikro Und Informationstechnik | Schulz M.,Hsg Imit Institute For Mikro Und Informationstechnik | Von Stetten F.,Hsg Imit Institute For Mikro Und Informationstechnik | Von Stetten F.,Albert Ludwigs University of Freiburg | And 5 more authors.
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2015

Lab-on-a-chip devices hold promise for automation of complex workflows from sample to answer with minimal consumption of reagents in portable devices. However, complex, inhomogeneous samples as they occur in environmental or food analysis may block microchannels and thus often cause malfunction of the system. Here we present the novel AutoDip platform which is based on the movement of a solid phase through the reagents and sample instead of transporting a sequence of reagents through a fixed solid phase. A ball-pen mechanism operated by an external actuator automates unit operations such as incubation and washing by consecutively dipping the solid phase into the corresponding liquids. The platform is applied to electrochemical detection of organophosphorus pesticides in real food samples using an acetylcholinesterase (AChE) biosensor. Minimal sample preparation and an integrated reagent pre-storage module hold promise for easy handling of the assay. Detection of the pesticide chlorpyrifos-oxon (CPO) spiked into apple samples at concentrations of 10-7 M has been demonstrated. This concentration is below the maximum residue level for chlorpyrifos in apples defined by the European Commission. © The Royal Society of Chemistry 2015.


Musat V.,University of Galati | Fortunato E.,New University of Lisbon | Purica M.,Romanian National Institute for Research and Development in Microtechnologies | Mazilu M.,University of Galati | And 3 more authors.
Materials Chemistry and Physics | Year: 2012

ZnO is a natural n-type widespread semiconductor with wide direct bandgap of 3.37 eV, large exciton bending energy (60 meV) and high optical gain (300 cm -1). One dimensional ZnO nanomaterials such as nanowires or nanorods have focused much attention due to their multifunctionality in optoelectronic devices, gas sensing, piezoelectricity and thin film transistors for transparent and flexible electronics. Solution-phase chemical synthesis of nanomaterials has several important advantages, as low temperatures, high versatility, low cost, simple equipments and handling. The paper presents the chemical bath deposition synthesis and characterization of ZnO 1D nanostructures grown on glass substrates seeded with gold layer, pre-prepared ZnO nanoparticles or sol-gel derived ZnO layer. The obtained ZnO nanowires/nanorods were structurally and morphologically characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and the growth mechanism is discussed. The seed layer significantly affects the surface distribution and orientation of the grown 1D nanostructures. The diameter of the nanowires is mainly controlled by the concentration and temperature of the growth solution. The effect of growth conditions on the surface chemical composition and surface states/defects of semiconducting 1D nanostructures was investigated using X-ray photoelectron spectroscopy. The optical and electrical properties are presented. © 2011 Elsevier B.V. All rights reserved.


Bazaru T.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Vlad V.I.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Petris A.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Miu M.,Romanian National Institute for Research and Development in Microtechnologies
Journal of Optoelectronics and Advanced Materials | Year: 2010

In this paper, we present a systematic experimental study of effective optical linear refractive index and third-order optical nonlinear effective susceptibility of nano-porous silicon samples with various values of silicon volume fill fractions. The experimental results are in good agreement with the theoretical predictions of our simplified Bruggeman formalism for effective optical linear and third-order nonlinear susceptibilities, which was previously presented. We derived the effective linear refractive index from measurements of the nano-porous silicon reflectivity. For the third-order optical nonlinearities measurements, we used the reflection intensity scan method. A new relation for the dependence of third-order effective nonlinear optical susceptibility on the silicon volume fill fraction (for nano-porous silicon samples with silicon volume fill fraction ≤ 0.5) and on measured nonlinear reflections (at λ = 633 nm) is derived and used to get the effective third-order nonlinear susceptibility.


Pachiu C.,Romanian National Institute for Research and Development in Microtechnologies
Proceedings of the International Semiconductor Conference, CAS | Year: 2012

The author deal with a two-dimensional phononic structure (PC) composed by a matrix of nylon with cylindrical holes filled with air. The fabrication process is 3D selective laser sintering where a pulsed laser is used to raise a powder at the temperature of diffusion to a solid state. A piezoelectric transducer emits a longitudinal wave and another transducer acts as a receiver, this basic set-up leads to the experimental spectrum of the transmission coefficient in the PC. The results are compared with the numerical dates and dispersion curves (ω, k), the existences of forbidden frequency bands are experimentally shown. The extension of this experimental study into other phononic crystals could lead to new physical phenomena at different scales and novel design of engineering devices. © 2012 IEEE.


Muller A.A.,Romanian National Institute for Research and Development in Microtechnologies | Soto P.,Polytechnic University of Valencia | Dascalu D.,Romanian National Institute for Research and Development in Microtechnologies | Dascalu D.,Polytechnic University of Bucharest | And 3 more authors.
IEEE Microwave and Wireless Components Letters | Year: 2011

This letter proposes a spherical 3-D Smith Chart suitable for representing both active and passive microwave circuits. Using the mathematical concept of the Riemann sphere, the extended reflection coefficient plane is transformed into the surface of the unit sphere. Since the proposed Smith Chart compiles the whole complex plane, all possible loads are included. A simple graphic tool is thus obtained that successfully unifies active and passive circuits. In addition, lossy lines with complex characteristic impedances can also be represented. The letter presents the 3-D Smith Chart, provides its main governing equations, and also enumerates its more important properties. © 2011 IEEE.


Stanciu I.,Romanian National Institute for Research and Development in Microtechnologies
UPB Scientific Bulletin, Series C: Electrical Engineering | Year: 2012

This paper presents an analysis of the dispersion of in plane dimensions of microfluidic structures fabricated by photolithography in SU-8 resist. An experimental study of the process parameters influence on the variation of the in plane dimensions is performed and an optimum value for process parameters to minimize this variation is determined. Using the established process parameters, a sample of wafers with microfluidic test structures is realized. Measurement results of this sample are used to perform a statistic analysis and a mathematical model of the variation of in plane geometric dimensions as consequence of the fabrication dispersion is built.


Muller A.A.,Romanian National Institute for Research and Development in Microtechnologies | Dascalu D.,Romanian National Institute for Research and Development in Microtechnologies
2011 IEEE MTT-S International Microwave Workshop Series on Millimeter Wave Integration Technologies, IMWS 2011 | Year: 2011

The paper exploits the geometrical properties of the Möbius transformations in an novel manner. Standard geometrical shapes as circles and spirals are directly related to the characteristic and input impedances of lossy transmission lines. Unexploited properties of inversive geometry applied to the lossy transmission lines make room for new boundaries for the impedances. Elements of visual complex analysis can be used in order to obtain margins for the real and imaginary parts of the input and characteristic impedances. © 2011 IEEE.


Neculoiu D.,Romanian National Institute for Research and Development in Microtechnologies | Bunea A.-C.,Romanian National Institute for Research and Development in Microtechnologies | Calmon P.,CNRS Laboratory for Analysis and Architecture of Systems | Takacs A.,CNRS Laboratory for Analysis and Architecture of Systems
2012 IEEE Asia-Pacific Conference on Antennas and Propagation, APCAP 2012 - Proceedings | Year: 2012

This paper presents a 140 GHz wide-band double folded slot (DFS) antenna structure. The radiation of the two radiating elements is combined, resulting in a gain of 6.4 dBi at 140 GHz. The structure is designed on a thin dielectric membrane, in order to reduce the dielectric losses as well as the losses due to the surface wave excitation. The antenna gain is greater than 5 dBi between 130-146 GHz, while the reflection losses are lower than -10 dB between 124-164 GHz, resulting in a large fractional bandwidth of ∼29%. © 2012 IEEE.


Bunea A.-C.,Romanian National Institute for Research and Development in Microtechnologies | Neculoiu D.,Romanian National Institute for Research and Development in Microtechnologies | Calmon P.,CNRS Laboratory for Analysis and Architecture of Systems | Takacs A.,CNRS Laboratory for Analysis and Architecture of Systems
Proceedings of the International Semiconductor Conference, CAS | Year: 2012

In this paper we present the electromagnetic modeling, fabrication and experimental results of a on-chip 2x1 folded slot dipole antenna array manufactured through silicon micromachining, working in the 60 GHz band. The measurements are in very good agreement with the simulations and demonstrate a large working band of ∼20% (54-65 GHz) for a return loss better than 10 dB. © 2012 IEEE.


Plugaru R.,Romanian National Institute for Research and Development in Microtechnologies | Sandu T.,Romanian National Institute for Research and Development in Microtechnologies | Plugaru N.,National Institute of Materials Physics Bucharest
Results in Physics | Year: 2012

Based on first principles electronic structure calculations using the Coherent Potential Approximation (CPA) in the Blackman-Esterling-Berk (BEB) multiscattering formalism and the variable range hopping (VRH) model proposed by Mott, we evaluate the low temperature dc conductivity and its temperature dependence for n-doped wurtzite-type M:ZnO, with M = Al, Ti, Mn, at concentrations of 2, 5 and 10. at.% respectively. We theoretically determine the phenomenologic quantities in the expression of the hopping conductivity, as well as the temperature range in which the VRH model is applicable to the investigated compounds. We show that self-consistent CPA-BEB and LSDA+U calculations yield reasonable band gaps, dopant state localization and also spin magnetic moments for the Ti and Mn systems. These results are discussed in comparison with reported data obtained by supercell LSDA+U calculations for similar systems. The results in this study point to 2-5. at.% Ti and approximately 2. at.% Al codoping in wurtzite-type ZnO as an interesting option to obtain a material with an increased low temperature dc conductivity and ferromagnetic background. © 2012 Elsevier B.V.

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