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In this work, an electrochemical transducing platform constructed from carbonaceous tubes modified with thiophene polymer and gold nanoparticles was described. The negatively charged carbon tubes attracted monomers on their surface, then migrated toward the electrode upon electrical driving force, and finally deposited on the electrode surface. Consequently, these carbon tubes were coiled and wrapped with prolonged conjugated polymer chains. Gold nanoparticles were found to be mainly nucleated and grown at highly conductive sites on carbon tubes. The combination of 2-D polymer segments, 1-D carbon tubes, and 0-D metal particles has resulted in a highly porous 3-D architecture which is crucial to increasing the electrochemical responses. Meanwhile, the charge propagation was promoted due to synergistic effect between these biocompatible and conductive materials and evidenced by a significant increase in charge transfer rate (3.5 times) and dramatic reduction in charge transfer resistance (disappearance of semicircle in Nyquist plot). The acetylcholinesterase sensor based on as-prepared hybrid film shows good attraction to acetylthiocholine (Kappm = 0.182 mM). Thus, the developed sensor will provide a promising tool to analyze neurotransmitters and enzyme inhibitors.

Magnetically separable core/shell Fe

In this work, we study the magnetic properties of nickel nanowires by measuring their anisotropic magnetoresistance at room temperature. The single nickel nanowire is grown by electrodeposition in a polymer membrane (Polycarbonate). We measure the anisotropic magnetoresistance effect of nickel nanowires for the various values of the magnitudes and orientations of an external magnetic field. The results clearly show the existence the anisotropic magnetoresistance effect in the nickel nanowires. Besides, the experimental data are best fit to the analytical calculations using the Stoner-Wohlfarth model for the magnetization of the wires.

This thesis is a study in the field of "Spin Caloritronics". This work focuses on the anisotropic magnetothermal transport in ferromagnetic thin film. The aim of this study is to determine the relationship between thermal transport and the magnetization state of the ferromagnetic thin layer. We show the experiments we used to do both electrical and thermal transport measurements. We also present a set of theoretical tools (model, calculation and simulation) which allows a better understanding of the experimental results. The first goal is to define the magnetization state of the sample by the measuring both the magnetoresistance and Hall effect (planar and anomalous). These measurements allow finding all the parameters necessary to the description of the magnetization equilibrium state so that we accurately know the magnetization state of our ferromagnetic thin film. The second goal is to find the angular dependence of thermal transport and to compare it with the angular dependence of electrical transport. To do so, we replace the electric current by a heat current end then do transverse voltage measurements for different angles. The results show that the measured voltage with a heat current has the same behavior as the transverse voltage measured with an electric current., Cette thèse est une étude s'inscrivant dans le domaine de la "Spin Caloritronics". Nous avons étudié le transport thermique anisotrope dans les couches minces ferromagnétiques. Le but de cette étude est de déterminer les relations entre le transport thermique et les états d'aimantation de la couche mince ferromagnétique. Nous présentons tous les protocoles expérimentaux qui permettent de faire les mesures de transports électriques et thermiques. Nous présentons également les outils (le modèle, les calculs et la simulation numérique) nécessaires pour analyser finement les résultats de mesure. Le premier objectif est la caractérisation des états d'aimantations des échantillons en utilisant des mesures de magnétorésistance et des mesures d'effets Hall (planaire et anormal). Tous les paramètres permettant de décrire les états d'équilibres magnétiques sont alors déterminés. Nous pouvons ainsi connaître très précisément les états d'aimantation de la couche mince ferromagnétique. Le deuxième objectif est de déterminer la dépendance angulaire du transport thermique anisotrope et de la comparer à celle du transport électrique anisotrope. Pour cela nous remplaçons le courant électrique par un courant de chaleur et effectuons toutes les mesures de tension transverse. Les résultats obtenus montrent que la tension transverse du courant de chaleur a la même dépendance angulaire que la tension transverse obtenue avec un courant électrique.