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Pongracz A.,Institute for Technical Physics and Material Science | Fekete Z.,Institute for Technical Physics and Material Science | Marton G.,Institute for Technical Physics and Material Science | Marton G.,Institute of Cognitive Neuroscience and Psychology | And 5 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

In this paper, the fabrication method, electrical and fluidic characterization and in vivo testing of the first deep brain silicon multielectrode with monolithically integrated fluidic channel are presented in details. Micromachined silicon probes with monolithically integrated microfluidic channels up to 70 mm length have been realized to perform simultaneous electrical recording and drug delivery in deep brain regions. The achieved cross-sectional dimension of the microchannels is in the range of 5-30 μm, while the length of the channel can be even 70 mm long.Fabrication process and integration of the drug delivery channels and the Pt recording sites are described. Electrical characterization and impedance tuning of the developed probes are also demonstrated. The functionality of the microfluidic channels is verified and the hydrodynamic characteristics (flow rate vs. injection pressure) are measured in the case of several length and cross-sections.Feasibility of our integration concept is proved by locally injected bicuculline in the cortex and in the thalamical regions of rat brain in vivo, while simultaneously recording the electrical signals of the stimulated neurons on four different electrical channels. © 2013 Elsevier B.V.


Palla-Papavlu A.,University of Bucharest | Palla-Papavlu A.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Palla-Papavlu A.,Paul Scherrer Institute | Filipescu M.,Romanian National Institute for Lasers, Plasma and Radiation Physics | And 9 more authors.
Journal of Physics D: Applied Physics | Year: 2016

Nanostructured tungsten trioxide (WO3) thin films are deposited by pulsed laser deposition (PLD) and radio-frequency (RF) assisted PLD onto interdigitated sensor structures. Structural characterization by x-ray diffraction and Raman spectroscopy shows the WO3 films are polycrystalline, with a pure monoclinic phase for the PLD grown films. The as-fabricated WO3 sensors are tested for ammonia (NH3) detection, by measuring the electrical response to NH3 at different temperatures. Sensors based on WO3 deposited by RF-PLD do not show any response to NH3. In contrast, sensors fabricated by PLD operating at 100 °C and 200 °C show a slow recovery time whilst at 300 °C, these sensors are highly sensitive in the low ppm range with a recovery time in the range of a few seconds. The microstructure of the films is suggested to explain their excellent electrical response. Columnar WO3 thin films are obtained by both deposition methods. However, the WO3 films grown by PLD are porous, (which may allow NH3 molecules to diffuse through the film) whereas RF-PLD films are dense. Our results highlight that WO3 thin films deposited by PLD can be applied for the fabrication of gas sensors with a performance level required for industrial applications. © 2016 IOP Publishing Ltd.


Vegetti A.,Polytechnic of Milan | Radnoczi G.,Institute for Technical Physics and Material Science | Ossi P.M.,Polytechnic of Milan
Carbon | Year: 2013

Selected ultra-high molecular weight polyethylene (UHMWPE) samples extracted from controlled positions along a representative reel from which ski bases are made were analyzed and compared to each other to test their composition and homogeneity. Scanning electron microscopy shows a UHMWPE matrix in which spherical particles are partly agglomerated and homogeneously distributed. Transmission electron microscopy, besides this, reveals the presence of a minority species, namely plate-like inclusions dispersed throughout the matrix. Raman features are traced back to structurally disordered carbonaceous material, with trigonal bond coordination. Surface electrical resistivity is quite low as compared to typical values for UHMWPE, being critically affected by the amount and spatial distribution of carbon particles. The observed homogeneity of distribution of carbon particles in the matrix is likely to be responsible for its ability to dissipate in an effective way the considerable amount of heat generated during ski gliding on hard, packed snow, thus preventing major structural damage of ski bases.


Galkin K.N.,Far Eastern Federal University | Galkin N.G.,Far Eastern Federal University | Dozsa L.,Institute for Technical Physics and Material science | Dotsenko S.A.,Far Eastern Federal University | And 4 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2013

Mg2Si layers were grown on silicon by RDE at 150 °C and by SPE at 160 °C, and they were covered by silicon cap grown by MBE at 150-180 °C. The silicide layers and the silicon cap were investigated by in situ and ex situ methods. The 2D Mg2Si layer continuity and electrical properties were conserved during cap growth. The point defects in the structure are dominated by contamination of the substrate and by diffusion of the not reacted Mg into silicon. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Pongracz A.,Institute for Technical Physics and Material Science | Fekete Z.,Institute for Technical Physics and Material Science | Marton G.,Institute for Technical Physics and Material Science | Fiath R.,Institute of Cognitive Neuroscience and Psychology | And 3 more authors.
Procedia Engineering | Year: 2012

Silicon micromachined deep brain multielectrodes (up to 70 mm) with monolithically integrated microfluidic channels have been realized to perform simultaneous electrical recording and drug delivery in deep brain regions. Fabrication process of the drug delivery channels and the Pt recording sites is demonstrated. Electrical characterization, impedance tuning and in-vivo testing of the developed probes are also presented. The functionality of the buried microfluidic channel is verified and pressure-flow characteristic of the channel is established. © 2012 The Authors. Published by Elsevier Ltd.


Fekete Z.,Institute for Technical Physics and Material Science | Nemeth A.,Institute for Technical Physics and Material Science | Marton G.,Institute for Technical Physics and Material Science | Ulbert I.,Institute of Cognitive Neuroscience and Psychology | And 2 more authors.
17th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2013 | Year: 2013

Due to the rapid development in micro- and nanofabrication technologies, several types of medical implants have been proposed and applied successfully in neurosurgery. In order to determine the safety margins and design rules of newly emerged realization techniques, in vivo mechanical characterisation is essential to be performed. In this work, experimental investigation is presented focusing on the interaction between rat brain tissue and single-shaft silicon microprobes fabricated by deep reactive ion etching. Physical parameters like penetration force and dimpling were studied in terms of insertion speed (mm/min range) and microprobe cross-section. Insertions were performed through intact dura and pia mater.

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