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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.

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.

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.

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.

Scurtu R.,Romanian Academy of Sciences | Scurtu R.,Romanian National Institute for Research and Development in Microtechnologies | Somacescu S.,Romanian Academy of Sciences | Calderon-Moreno J.M.,Romanian Academy of Sciences | And 5 more authors.
Journal of Solid State Chemistry | Year: 2013

Nanocrystalline Sm0.5Sr0.5CoO3-δ powders were synthesized by a chelating route using different polyfunctional HxAPC acids (APC=aminopolycarboxylate; x=3, 4, 5). Different homologous aminopolycarboxylic acids, namely nitrilotriacetic (H 3nta), ethylenediaminetetraacetic (H4edta), 1,2-cyclohexanediaminetetracetic (H4cdta) and diethylenetriaminepentaacetic (H5dtpa) acid, were used as chelating agents to combine Sm, Sr, Co elements into a perovskite structure. The effects of the chelating agents on the crystalline structure, porosity, surface chemistry and electrical properties were investigated. The electrical properties of the perovskite-type materials emphasized that their conductivities in the temperature range of interest (600-800 C) depend on the nature of the precursors as well as on the presence of a residual Co oxide phase as shown by XRD and XPS analysis. The surface chemistry and the surface stoichiometries were determined by XPS revealing a complex chemical behavior of Sr that exhibits a peculiar "surface phase" and "bulk phase" chemistry within the detected volume (<10 nm). © 2013 Elsevier Inc.

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