Discrimination of dopamine and ascorbic acid using carbon nanotube fiber microelectrodes

3 pagesInternational audienceThe detection of dopamine is a scientific challenge of great importance for the understanding of neurobiological dysfunctions. However the presence of ascorbic acid at concentrations several times higher than that of dopamine and its oxidation at a very similar potential make a selective electrochemical detection difficult. Here we report the original and intrinsic selectivity of carbon nanotube (CNT) fiber microelectrodes (CNTFM) towards dopamine oxidation without significant interaction from ascorbic acid

Hydroxide Ions Stabilize Open Carbon Nanotubes in Degassed Water

The main hurdle preventing the widespread useof single-walled carbon nanotubes remains the lack ofmethods with which to produce formulations of pristine,unshortened, unfunctionalized, individualized single-walledcarbon nanotubes, thus preserving their extraordinary properties.In particular, sonication leads to shortening, which isdetrimental to percolation properties (electrical, thermal,mechanical, etc.). Using reductive dissolution and transfer intodegassed water, open-ended, water-filled nanotubes can bedispersed as individualized nanotubes in water−dimethylsulfoxide mixtures, avoiding the use of sonication andsurfactant. Closed nanotubes, however, aggregate immediately upon contact with water. Photoluminescence andabsorption spectroscopy both point out a very high degree of individualization while retaining lengths of several microns.The resulting transparent conducting films are 1 order of magnitude more conductive than surfactant-based blanks atequal transmittance

Nanotube fibers for electromechanical and shape memory actuators

9 pagesInternational audienceCarbon nanotubes are light, stiff and electroactive materials particularly promising in the field of actuating materials. Indeed, carbon nanotubes can expand and contract upon charge injection and be used for the development of electromechanical actuators. Carbon nanotubes can also be included in polymers to improve their properties and bring specific functionalities. When added to shape memory polymers, carbon nanotubes yield an improved stiffness and the possibility to heat the material through Joule's heating. Nevertheless, spatial ordering of the nanotubes is a critical issue in all these classes of actively moving materials. It is shown in this article that assembling nanotubes under the form of pure or composite fibers is an effective approach to orient carbon nanotubes on a large scale along a well defined direction. Nanotube alignment achieved via fiber drawing allows the optimization of properties of shape memory polymer fibers and electrochemical actuators. In particular, the mechanical response of pure nanotube fibers to electrical stimulations is investigated in liquid electrolytes. It is observed that the fibers can generate a stress one order of magnitude greater than that achieved with unaligned assemblies of nanotubes. We also present the properties of shape memory polymer fibers loaded with carbon nanotubes. These fibers generate a very large stress when they recover their shape after they have been stretched and cooled under tensile load. Composite nanotube polymer fibers also exhibit a temperature memory behavior, which is still raising fundamental questions regarding its microscopic origin