Search results for "Microelectrodes"
showing 8 items of 28 documents
Impedance characterization of the electrochemical environment under a polymer film artificially delaminated
2008
International audience; Knowledge of the electrical conductivity of the zone under a delaminated paint film is one necessary input parameter for the simulation of electrochemically driven underpaint corrosion. In this work, a microelectrode array system has been developed, tested, and applied to measure the spatial distribution of resistivity in the delaminated zone along the metal/polymer interface. The experimental device consists of a linear array of six 100 m diameter stainless steel microelectrodes (100 m in diameter) embedded in a steel substrate. A polymer coatingwas applied and an artificial "delaminated zone"was created using the laser-induced decohesion technique. The electrochemi…
Formation and Rupture of Schottky Nanocontacts on ZnO Nanocolumns
2007
In this paper, the electrical transport and mechanical properties of Pt/ZnO Schottky nanocontacts have been studied simultaneously during the formation and rupture of the nanocontacts. By combining multidimensional conducting scanning force spectroscopy with appropriated data processing, the physical relevant parameters (the ideality factor, the Schottky barrier height, and the rupture voltage) are obtained. It has been found that the transport curves strongly depend on the loading force. For loading forces higher than a threshold value, the transport characteristics are similar to those of large-area Schottky contact, while below this threshold deviations from strictly thermionic emission …
EFFECT OF MICROENCAPSULATION ON OXYGEN DISTRIBUTION IN ISLETS ORGANS
1994
In islet transplantation, limitation of oxygen supply may restrict graft function, particularly when encapsulated tissue is used. Therefore, oxygen tensions (PO2) in isolated islet organs (Brockmann bodies) of Osphronemus gorami were measured. In a thermostatically (37 degrees C) controlled measuring chamber, PO2 values were recorded at subsequent microelectrode positions on a radial track toward the center of the organ. In 2 independent groups, we studied the effect of fluid convection (n = 12) and microencapsulation (n = 12). In both groups, sigmoidal PO2 profiles were found, which permit differentiation in an oxygen-depleted zone surrounding the surface, a steep decline inside the tissue…
A method for rapid implantation of multielectrode systems.
1991
The implantation of several chronic electrodes at the same time was needed for the studies in which both evoked slow potential and multiple unit neural activity of different brain sites were recorded during classical conditioning in freely moving cats. The recording electrodes were made of 25-75 microns insulated stainless steel or nichrome wires which were inserted into a thin hypodermic needle of a fixed, calibrated length. The fast implantation system described here is based on the use of a stereotaxic frame as a stand for a drill and as a support for an electrode holder with which the electrodes were implanted through precision holes drilled directly according to the coordinates of the …
Computer simulation of oxygen tension histograms--a possibility for interpretation of microelectrode measurements.
1972
Mit Sauerstoff-Mikroelektroden werden die lokalen Werte des Sauerstoffpartialdruckes im Mikrobereich der Organe gemessen und graphisch als Haufigkeitsverteilungen (Histogramme) dargestellt. Theoretisch wird der Einfluss der Kapillaranordnung (Gleich-, Gegenstromsystem und Kapillarnetzwerk) auf die Haufigkeitsverteilung der P02 Werte untersucht. Die fur zweidimensionale Modelle durchgefuhrte Analyse zeigt, dass Unterschiede in der Durchblutung, wie sie in den einzelnen Zweigen der Kapillarnetzwerke auftreten, einen starken Einfluss auf die Histogramme haben.
Aligned microcontact printing of biomolecules on microelectronic device surfaces
2001
Microcontact printing (/spl mu/CP) of extracellular matrix proteins is a fascinating approach to control cell positioning and outgrowth, which is essential in the development of applications ranging from cellular biosensors to tissue engineering. Microelectronic devices can be used to detect the activity from a large number of recording sites over the long term. However, signals from cells can only be recorded at small sensitive spots. Here, the authors present an innovative setup to perform aligned /spl mu/CP of extracellular matrix proteins on microelectronic devices in order to guide the growth of electrogenic cells specifically to these sensitive spots. The authors' system is based on t…
Chronic neural probe for simultaneous recording of single-unit, multi-unit, and local field potential activity from multiple brain sites
2017
Drug resistant focal epilepsy can be treated by resecting the epileptic focus requiring a precise focus localisation using stereoelectroencephalography (SEEG) probes. As commercial SEEG probes offer only a limited spatial resolution, probes of higher channel count and design freedom enabling the incorporation of macro and microelectrodes would help increasing spatial resolution and thus open new perspectives for investigating mechanisms underlying focal epilepsy and its treatment. This work describes a new fabrication process for SEEG probes with materials and dimensions similar to clinical probes enabling recording single neuron activity at high spatial resolution.Polyimide is used as a bi…
Contribution of area 19 to the foreground-background-interaction of the cat: an analysis based on single cell recordings and behavioural experiments.
1990
The contribution of area 19 to pattern discrimination in the cat was studied by single cell recordings in this area and by behavioural experiments before and after bilateral lesions. In order to make quantitative comparisons between behavioural performance and that of cell systems, we introduced a new parameter that characterizes visual neurons by their signal-to-noise (S/N) thresholds. A structured visual background made up of Gaussian visual broadband noise which could be moved was superimposed on the signal (moving bars or outline patterns) and the S/N characteristics of the response were determined by varying the signal intensity. The detection performance of cats after bilateral lesion…