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.
Electroless polymerization of aniline on platinum is investigated for polyaniline micro- and nanostructuring into practical electronic devices. This type of reaction is adapted to estimate its usefulness in a lithographic process. For practical electronic device fabrication, electroless polymerization of aniline can be used to electrically bridge initially independent platinum electrodes. As this application requires a polyaniline bridge to form over a nonconductive material before an electrical contact is obtained, polyaniline growth using chemical oxidative reaction is investigated on substrates presenting surface-tension contrast patterns.
Polyaniline (PANi), as conductive polymer, constitutes an attractive material for electronic and optical applications. Different from electropolymerization and chemical oxidative polymerization, electroless deposition is another method for synthesizing PANi. Aniline can polymerize slowly and spontaneously on platinum or palladium surface in an aqueous acid solution of the monomer. This reaction proceeds via an electrochemical mechanism that involves the reduction of dissolved oxygen as cathodic and oxidation of aniline as anodic half-reactions at the metal/solution interface. PANi, obtained by electroless synthesis, was compared to chemical oxidative and electropolymerized ones by XPS and SEM. The product of electroless deposition is found to be chemically similar to the others but its morphology is different. The PANi film growth and morphology are studied as a function of time and temperature.
Polyaniline (PANi) nanowires and nanotubes are processed by electrospinning. Nanowires are electrospinned using PANi/PEO and PANi/PMMA polymer blends. The morphology and composition of these nanofibers are determined by scanning electron microscopy (SEM) and Nano-Secondary Ion Mass Spectrometry (Nano-SIMS). The conductive polymer seems more homogeneously distributed for the PANi/ PEO than for the PANi/PMMA blend nanowires, which exhibit a phase separation. On the other hand, pure PANi nanotubes are prepared using PMMA nanowires as a template. The synthesis is followed by X-ray photoelectron spectroscopy (XPS), SEM and Nano-SIMS. Moreover, a simple method based on electrostatic steering allows us to align these fibers on a substrate.
Breath figure films of polystyrene and polyalkylthiophene presenting regular patterns of 600 nm and 5 mm are used as templates to prepare negative polydimethylsiloxane stamps containing an entrapped quantity of the primary polymer. These breath figure replica are used to generate single or double layers of the entrapped conjugated polymer in the form of networks on any substrates. Besides this, polystyrene printed in this way can be used as a resist mask that allows the polymerization of aniline in a regular micrometric arrangement on a platinum electrode or to generate a regular acid/base patterning on a plain polyaniline film.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.