Publikationen


Suche nach „[M.] [Mátéfi-Tempfli]“ hat 96 Publikationen gefunden
Suchergebnis als PDF
    DigitalMobilEuropan Campus Rottal-Inn

    Beitrag (Sammelband oder Tagungsband)

    L. Patane, T. Hoinville, H. Cruse, M. Schilling, A. Drimus, P. Arena, Ch.J. Dallmann, T. Krause, R. Strauss, A. Schneider, V. Dürr, J. Paskarbeit, A. Vitanza, Stefan Mátéfi-Tempfli, J. Schmitz

    Integrative Biomimetics of Autonomous Hexapedal Locomotion

    [Review paper under publication]

    Proceedings of IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) [November 3-8, 2019; Macau, China]

    2019

    DigitalMobilEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    W. Benecke, J. Adam, M. Mátéfi-Tempfli, T. Reimer, de Oliveira Hansen, R. M. D., R. Safonovs, B. Wagner, S. Chemnitz, Stefan Mátéfi-Tempfli

    Magnetic films for electromagnetic actuation in MEMS switches

    Microsystem Technologies, vol. 24, no. 4, pp. 1987-1994

    2018

    DOI: 10.1007/s00542-017-3595-2

    Abstract anzeigen

    This paper investigates the fabrication of magnetic films via electroplating to be applied into electromagnetic actuated micro electro-mechanical systems (MEMS) switches. Cobalt and nickel films (1 µm thicknesses) were deposited on gold coated silicon substrates via electrochemical deposition. Different deposition conditions were investigated, regarding temperature and deposition voltage. The films morphologies were characterized via atomic force microscopy, while the magnetic properties of the films were characterized via vibrating sample magnetometer measurements. In order to evaluate the integration of these magnetic films into MEMS switches with low energy consumption, a mathematical model was developed and the results show that these films can be applied into efficient actuation with reduced power dissipation.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    D. Cook, M. Mátéfi-Tempfli, P. Richardson, M. Bampton, T. Cookson, D. Smith, J. Branch, Stefan Mátéfi-Tempfli, P. Connell, P. Bartlett, M. Alibouri

    Plastic Reactor Suitable for High Pressure and Supercritical Fluid Electrochemistry

    Journal of The Electrochemical Society, vol. 164, no. 6

    2017

    Abstract anzeigen

    The paper describes a reactor suitable for high pressure, particularly supercritical fluid, electrochemistry and electrodeposition at pressures up to 30 MPa at 115°C. The reactor incorporates two key, new design concepts; a plastic reactor vessel and the use of o-ring sealed brittle electrodes. These two innovations widen what can be achieved with supercritical fluid electrodeposition. The suitability of the reactor for electroanalytical experiments is demonstrated by studies of the voltammetry of decamethylferrocene in supercritical difluromethane and for electrodeposition is demonstrated by the deposition of Bi. The application of the reactor to the production of nanostructures is demonstrated by the electrodeposition of ∼80 nm diameter Te nanowires into an anodic alumina on silicon template. Key advantages of the new reactor design include reduction of the number of wetted materials, particularly glues used for insulating electrodes, compatability with reagents incompatible with steel, compatability with microfabricated planar multiple electrodes, small volume which brings safety advantages and reduced reagent useage, and a significant reduction in experimental time.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    G. Denuault, M. Mátéfi-Tempfli, H. Bülter, C. Dosche, Stefan Mátéfi-Tempfli, G. Wittstock

    Electrochemical analysis of nanostructured iron oxides using cyclic voltammetry and scanning electrochemical microscopy

    Electrochimica Acta, vol. 222, pp. 1326-1334

    2016

    Abstract anzeigen

    Iron oxides in general and especially hematite, α-Fe2O3, have become promising materials for the alkaline water electrolysis and photoelectrochemical water splitting, respectively. In the present study electrocatalytic electrodes with a thin film of α-Fe2O3 and with vertically aligned α-Fe2O3 nanowires were prepared. Cyclic voltammograms of the α-Fe2O3 nanowires revealed differences including a series of three unreported cathodic signals when compared to previously published voltammograms for polycrystalline iron oxides. The generation-collection mode of scanning electrochemical microscopy (SECM) using nanostructured Pt microdisc probes was exploited to detect soluble reaction products formed at the voltammetric peaks of the α-Fe2O3 electrode. SECM tip-substrate voltammetry unexpectedly showed that the reduction of FeVI to FeIII on the cathodic sweep is accompanied by significant O2 evolution.

    DigitalNachhaltigEuropan Campus Rottal-Inn

    Beitrag (Sammelband oder Tagungsband)

    M. Gorsic, A. Drimus, Stefan Mátéfi-Tempfli, V. Jankovics

    High Resolution Tactile Sensors for Curved Robotic Fingertips

    Biomimetic and Biohybrid Systems, Cham, vol. 8608 : Lecture notes in artificial intelligence

    2014

    ISBN: 978-3-319-09435-9

    DOI: 10.1007/978-3-319-09435-9_37

    Abstract anzeigen

    Tactile sensing is a key element for various animals that interact with the environment and surrounding objects. Touch provides information about contact forces, torques and pressure distribution and by the means of exploration it provides object properties such as geometry, stiffness and texture[5]. For humans, extracting high level information from touch provides a better understanding of the objects manipulated while for insects it is essential for locomotion[3]. While robot designers have been using vision systems to provide the robot with information about its surroundings, this is not always trivial to obtain, dealing with limited accuracy, occlusions and calibration problems. In terms of sensors for static stimuli, such as pressure, there are a range of technologies that can be used to manufacture transducers with various results[5]. A simple approach is to use fingertips with a 6-DOF force-torque sensor for estimating contact conditions[1], but this only allows a single point of contact and is costly. In terms of fingertip and foot tip prototypes, tactile sensors are used for multi modal sensing, similar to biology, for pressure and dynamic stimuli. In this respect Hosoda et al. [4] propose an anthropomorphic fingertip which has randomly distributed straingauges and PVDF (polyvinylidene fluoride) transducers. In [7] a biomimetic tactile array is proposed that shows a low hysteresis and good sensitivity for skin like deformations.

    DigitalEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    M. Gorsic, A. Drimus, Stefan Mátéfi-Tempfli, V. Jankovics

    Novel high resolution tactile robotic fingertips

    IEEE SENSORS, pp. 791-794

    2014

    DOI: 10.1109/ICSENS.2014.6985118

    Abstract anzeigen

    This paper describes a novel robotic fingertip based on piezoresistive rubber that can sense pressure tactile stimuli with a high spatial resolution over curved surfaces. The working principle is based on a three-layer sandwich structure (conductive electrodes on top and bottom and piezoresistive rubber in the middle). For the conductive layers we use ring patterns of silver epoxy and flex PCB electrode arrays. The proposed sensorised fingertip has 60 sensitive regions (taxels) arranged in 5 rings and 12 columns that have a smooth pressure to resistance characteristic. Using the sensor with specialized data acquisition electronics that acquire 500 frames per second provides rich information regarding contact force, shape and angle for bio-inspired robotic fingertips. Furthermore, a model of estimating the force of contact based on values of the cells is proposed.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    B. Rana, M. Mátéfi-Tempfli, M. Agrawal, A. Barman, R. Hicken, U.A.S. Al-Jarah, O. Dmytriiev, Gangmei P., L. Piraux, V. Kruglyak, Stefan Mátéfi-Tempfli, B. Mahato

    Static and dynamic magnetic properties of densely packed magnetic nanowire arrays

    Physical Review B, vol. 87, no. 17

    2013

    DOI: 10.1103/PhysRevB.87.174429

    Abstract anzeigen

    The static and dynamic magnetic properties of magnetic nanowire arrays with high packing density (>0.4) and wire diameter much greater than the exchange length have been studied by static and time-resolved magneto-optical Kerr effect measurements and micromagnetic simulations. The nanowires were formed by electrodeposition within a nanoporous template such that their symmetry axes lay normal to the plane of the substrate. A quantitative and systematic investigation has been made of the static and dynamic properties of the array, which lie between the limiting cases of a single wire and a continuous ferromagnetic thin film. In particular, the competition between anisotropies associated with the shape of the individual nanowires and that of the array as a whole has been studied. Measured and simulated hysteresis loops are largely anhysteretic with zero remanence, and the micromagnetic configuration is such that the net magnetization vanishes in directions orthogonal to the applied field. Simulations of the remanent state reveal antiferromagnetic alignment of the magnetization in adjacent nanowires and the formation of vortex flux closure structures at the ends of each nanowire. The excitation spectra obtained from experiment and micromagnetic simulations are in qualitative agreement for magnetic fields applied both parallel and perpendicular to the axes of the nanowires. For the field parallel to the nanowire axes, there is also good quantitative agreement between experiment and simulation. The resonant frequencies are initially found to decrease as the applied field is increased from remanence. This is the result of a change of mode profile within the plane of the array from nonuniform to uniform as the ground state evolves with increasing applied field. Quantitative differences between experimental and simulated spectra are observed when the field is applied perpendicular to the nanowire axes. The dependence of the magnetic excitation spectra upon the array packing density is explored, and dispersion curves for spin waves propagating within the array parallel to the nanowire axis are presented. Finally, a tunneling of end modes through the middle region of the nanowires was observed. The tunneling is more efficient for wires forming densely packed arrays, as a result of the extended penetration of the dynamic demagnetizing fields into the middle of the wires and due to the lowering of the tunneling barrier by the static demagnetizing field of the array.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    A. Milosavljević, M. Mátéfi-Tempfli, K. Schiessl, J. Burgdörfer, C. Lemell, B. Marinković, Stefan Mátéfi-Tempfli, K. Tökési

    Charging dynamics in electron transmission through Al2O3 capillaries

    Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, vol. 279, pp. 190-193

    2012

    Abstract anzeigen

    We have measured the transmission of low-energy electrons through insulating Al2O3 nanocapillaries. We find that transmission at the incident energy is quickly suppressed with increasing tilt angle of the capillary axis relative to the incoming electron beam while inelastic transmission becomes more important. For small angles of incidence charging dynamics lead to a decrease of total transmission (elastic and inelastic) with time. Our results are interpreted on the basis of a microscopic model for the electron transport within the capillary including also close interactions with the capillary wall.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    C.-H. Solterbeck, M. Mátéfi-Tempfli, M. Es-Souni, Stefan Mátéfi-Tempfli, S. Habouti

    On-substrate, self-standing Au-nanorods arrays showing morphology controlled properties

    Nano Today, vol. 6, no. 1, pp. 12-19

    2011

    DOI: 10.1016/j.nantod.2010.11.001

    Abstract anzeigen

    We use supported alumina templates and electrodeposition to fabricate self-standing Au-nanorods (Au-NR) arrays. Depending on electrolyte and deposition conditions two different NR morphologies with either corrugated or smooth topologies are fabricated. We show that the properties of the NR arrays, including amphiphilic and optical, very much depend on their morphology. Smooth NR arrays are hydrophobic while the corrugated ones are hydrophilic. Also the optical reflectance, though it shows plasmon resonances at very similar wave lengths, is much lower for the corrugated NR arrays. The activity of the NR arrays as substrates for molecular detection using Raman scattering, and Rhodamine 6G (R6G) as model dye, also strongly depends on their morphology. R6G concentrations down to 1 pM are detected on the corrugated arrays yielding an effective enhancement factor (EF) of approximately 1 × 109. In contrast an over-estimated (because of their hydrophobic character) EF of 6 × 106 is obtained for the smooth NR arrays.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    C.-H. Solterbeck, M. Mátéfi-Tempfli, M. Es-Souni, Stefan Mátéfi-Tempfli, S. Habouti

    Self-standing corrugated Ag and Au-Nanorods as plasmonic substrates

    Journal of Materials Chemistry, vol. 21, pp. 6269-6273

    2011

    Abstract anzeigen

    We use home-made Si-supported anodized alumina thin film templates for the electrodeposition of large area self-standing Ag- and Au-nanorod (Au-NR) arrays. The deposition conditions chosen, i.e. electrolyte composition and deposition voltage, lead to a corrugated rod morphology, particularly for Au-NRs. Instantaneous nucleation followed by diffusion-controlled growth are thought to be the dominating mechanism for the morphology observed. Diffuse reflectance spectra show specific behaviours of Ag- and Au-NRs with longitudinal and transverse plasmon resonance modes and additional modes for Ag-NRs. The activity of the NR arrays as substrates for molecular detection using Raman scattering and Rhodamine 6G (R6G) as a model dye strongly depends on noble metal. R6G concentrations down to 1 pM are detected on the corrugated arrays yielding an effective enhancement factor (EF) of approximately 2 × 1010 for Ag-NRs and 1 × 109 for Au-NRs. The latter is the highest ever obtained for Au-nanostructures. Both nanostructures provide an enhancement that is high enough to detect single molecules using Raman scattering. The results are rationalized in terms of morphology effects on electromagnetic field intensity.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    M. Mátéfi-Tempfli, L. Piraux, A. Vlad, S. Melinte, Stefan Mátéfi-Tempfli

    Vertical nanowire architectures: Statistical processing of porous templates towards discrete nanochannel integration

    Small, vol. 6, no. 18, pp. 1974-1980

    2010

    DOI: 10.1002/smll.201000723

    Abstract anzeigen

    Nanowires and statistics: A statistical process for reading ultradense arrays of nanostructured materials is presented (see image). The experimental realization is achieved through selective nanowire growth using porous alumina templates. The statistical patterning approach is found to provide rigorous selection rules for measuring well‐defined numbers of nanowires located into nanoporous templates, and provides a conceptual framework for the fabrication of nanowire‐based crossbar latches.

    Europan Campus Rottal-Inn

    Zeitschriftenartikel

    S. Biri, M. Mátéfi-Tempfli, Z. Juhász, G.A.B. Gál, I. Rajta, S. Szilasi, Stefan Mátéfi-Tempfli

    Nanochannel alignment analysis by scanning transmission ion microscopy

    Nanotechnology, vol. 21, no. 29

    2010

    DOI: 10.1088/0957-4484/21/29/295704

    Abstract anzeigen

    In this paper a study on the ion transmission ratio of a nanoporous alumina sample is presented. The sample was investigated by scanning transmission ion microscopy (STIM) with different beam sizes. The hexagonally close-packed Al2O3 nanocapillary array, realized as a suspended membrane of 15 µm thickness, had pore diameters of ~ 215 nm and spacing of ~ 450 nm. When the proton beam size was limited to a single domain, a peak transmission ratio of 19% was observed as is expected from the geometry (~19–20%). This result points out an almost perfectly parallel alignment of the capillaries within one domain. However, for larger beam scanning areas (sampling multiple domains) the transmission ratio was reduced to 5%. The STIM analysis over an area larger than the typical domain size revealed an overall capillary angular spread of ~ 2°.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    M. Mátéfi-Tempfli, L. Piraux, A. Vlad, Stefan Mátéfi-Tempfli, V. Antohe

    Nanowires and nanostructures fabrication using template methods: A step forward to real devices combining electrochemical synthesis with lithographic techniques

    Journal of Materials Science: Materials in Electronics, vol. 20, no. 1, pp. 249-254

    2009

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    B. Sulik, S. Biri, É. Fekete, M. Mátéfi-Tempfli, Z. Juhász, Gy. Víkor, J. Pálinkás, Stefan Mátéfi-Tempfli, K. Tőkési, I. Iván, E. Takács

    Ion Guiding in Alumina Capillaries: MCP Images of the Transmitted Ions

    Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms, vol. 267, no. 2, pp. 321-325

    2009

    DOI: 10.1016/j.nimb.2008.10.017

    Abstract anzeigen

    Transmission of a few keV impact energy Ne6+ ions through capillaries in anodic alumina membranes has been studied with different ion counting methods using an energy dispersive electrostatic spectrometer, a multichannel plate (MCP) array and sensitive current-measurement. In the present work, we focus our attention to the measurements with the MCP array. The alumina capillaries were prepared by electro-chemical oxidation of aluminium foils. For the present experiments guiding of 3-6 keV Ne6+ ions has been studied in two samples with capillary diameter of about 140 nm and 260 nm and with capillary length of about 15 μm. At these energies, the ions have been efficiently guided by the capillaries up to few degrees tilt angle. In this work, we compare the results obtained by the energy dispersive spectrometer to those studied by the MCP array.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    V. Moshchalkov, M. Mátéfi-Tempfli, S. Michotte, J. Vanacken, X. Hallet, L. Piraux, Stefan Mátéfi-Tempfli

    Artificial pinning centers using the barrier layer of ordered nanoporous alumina templates

    Journal of Physics: Conference Series, vol. 153, no. 1

    2009

    DOI: 10.1088/1742-6596/153/1/012013

    Abstract anzeigen

    The barrier layer of self-ordered anodized aluminium oxide, which is grown from an aluminium foil, has been revealed by a selective chemical etching of the remaining aluminium. The surface obtained in this way consists of a triangular lattice of bumps with 100nm spacing, and heights of approximately 50nm. Using this surface as a template for controlling the pinning in thin superconducting films, superconducting Nb was deposited with different thicknesses and under different deposition angles. The evaporation under a 30° angle shows an asymmetric pinning potential composed of two triangular lattices having different pinning strengths. Matching effects are observed up to 1T. Matching effects are also maintained at relatively low temperature.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    V. Moshchalkov, M. Mátéfi-Tempfli, S. Michotte, J. Vanacken, X. Hallet, L. Piraux, Stefan Mátéfi-Tempfli

    Quasi-hexagonal vortex pinning lattice using anodized aluminum oxide nanotemplates.

    Small, vol. 5, no. 21, pp. 2413-2416

    2009

    Abstract anzeigen

    The bottom barrier layer of well‐ordered nanoporous alumina membranes reveals a previously unexploited nanostructured template surface consisting of a triangular lattice of hemispherical nanoscale bumps. Quasi‐hexagonal vortex‐pinning lattice arrays are created in superconducting Nb films deposited onto this template (see image). Matching effects are preserved at higher magnetic fields and lower temperatures when compared to holes on the top face.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    V. Moshchalkov, M. Mátéfi-Tempfli, S. Michotte, J. Vanacken, X. Hallet, L. Piraux, Stefan Mátéfi-Tempfli

    High field matching effects in NbN induced by a dense ferromagnetic nanowires array grown in a nanoporous alumina template

    Applied Physics Letters, vol. 95, no. 25

    2009

    DOI: 10.1063/1.3276557

    Abstract anzeigen

    Dense arrays of ordered ferromagnetic nanowires have been used to create periodic magnetic pinning centers in thin superconducting NbN films. The nanowires were electrodeposited in a highly ordered porous alumina membrane and the thin NbN film was deposited on top of the perpendicularly oriented magnetic nanowires. Matching effects have been observed up to 2.5 T (11th matching field) and are maintained at low temperature. An appreciable enhancement of the superconducting properties is observed. At low fields, a hysteretic behavior in the magnetoresistance is found, directly related to the magnetization processes of arrays of interacting single domain ferromagnetic nanowires.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    P. Bertrand, S. Yunus, M. Mátéfi-Tempfli, A. Radu, C. Dutu, A. Attout, A. Vlad, Piraux L., S. Melinte, Stefan Mátéfi-Tempfli, V. Antohe

    Nanowire-Templated Microelectrodes for High-Sensitivity pH Detection

    Applied Physics Letters, vol. 94, no. 7

    2009

    DOI: 10.1063/1.3089227

    Abstract anzeigen

    A highly sensitive pH capacitive sensor has been designed by confined growth of vertically aligned nanowire arrays on interdigited microelectrodes. The active surface of the device has been functionalized with an electrochemical pH transducer (polyaniline). We easily tune the device features by combining lithographic techniques with electrochemical synthesis. The reported electrical LC resonance measurements show considerable sensitivity enhancement compared to conventional capacitive pH sensors realized with microfabricated interdigited electrodes. The sensitivity can be easily improved by changing only the thickness of the functional layer.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    P. Bertrand, S. Yunus, M. Mátéfi-Tempfli, A. Radu, C. Dutu, A. Attout, A. Vlad, Piraux L., S. Melinte, Stefan Mátéfi-Tempfli, V. Antohe

    Nanowire-Templated Microelectrodes for High-Sensitivity pH Detection

    Virtual Journal of Nanoscale Science & Technology (NanoUnion), vol. 19, no. 9

    2009

    Abstract anzeigen

    A highly sensitive pH capacitive sensor has been designed by confined growth of vertically aligned nanowire arrays on interdigited microelectrodes. The active surface of the device has been functionalized with an electrochemical pH transducer (polyaniline). We easily tune the device features by combining lithographic techniques with electrochemical synthesis. The reported electrical LC resonance measurements show considerable sensitivity enhancement compared to conventional capacitive pH sensors realized with microfabricated interdigited electrodes. The sensitivity can be easily improved by changing only the thickness of the functional layer.

    NachhaltigEuropan Campus Rottal-Inn

    Zeitschriftenartikel

    A. Milosavljević, Marinković B. P., Šević D., M. Mátéfi-Tempfli, J. Jureta, Z. Pešić, Víkor Gy., Stefan Mátéfi-Tempfli

    Low-energy electron transmission through high aspect ratio Al2O3 nanocapillaries.

    EPL - A Letters Journal Exploring the Frontiers of Physics, vol. 86, no. 2

    2009

    DOI: 10.1209/0295-5075/86/23001

    Abstract anzeigen

    Electron transmission through insulating Al2O3 nanocapillaries of different diameters (40 and 270 nm) and 15 μm length has been investigated for low-energy electrons (2–120 eV). The total intensity of transmitted current weakly depends on the incident electron energy and tilt angle defined with respect to the capillary axis. On the other hand, the intensity of elastically transmitted electrons significantly varies with the alteration of electron energy and tilt angle. In addition, we measured an energy distribution of electrons transmitted both in the straightforward direction and at large tilt angle. The measured spectra show that inelastic processes dominate and, in particular, a large amount of low-energy electrons. These low-energy electrons can be either inelastically scattered projectiles or secondary electrons emitted within the capillaries. Furthermore, a change of the tilt angle appears to influence significantly only the intensity of the elastic transmission. The present results suggest a more complex nature of low-energy electron transport through insulating nanocapillaries than proposed for positive ions.