Carbon Nanotubes For Sensor Applications Research Articles

Chemically treated multi-walled carbon nanotubes for sensor applications

Chemically treated multi-walled carbon nanotubes for sensor applications

DFT investigations of the piezoresistive effect of carbon nanotubes for sensor application

AbstractWe investigate the piezoresistive effect of carbon nanotubes (CNTs) within density functional theory (DFT) aiming at application‐relevant CNTs. CNTs are excellent candidates for the usage in nano‐electromechanical sensors (NEMSs) due to their small band gap at zero strain leading to a finite resistivity at room temperature. The application of strain induces a band gap‐opening leading to a tremendous change in the resistivity. DFT with the LDA approximation yields reasonable results for pure carbon systems like CNTs and is applied to calculate the electronic structure of experimentally relevant CNTs. For the transport part, a simple ballistic transport model based on the band gap is used. We compare our DFT results for the band gaps of strained CNTs to results of tight binding (TB) models. By introducing a scaling factor of $\sqrt {2} $, an excellent agreement of the DFT data with TB model, published by Yang and Han [Phys. Rev. Lett. 85, 154 (2000)], is obtained.

Lignin-based polyurethane doped with carbon nanotubes for sensor applications

Modified eucalyptus kraft lignin doped with multiwall carbon nanotubes (MWCNTs) was used as a macromonomer in step-growth polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol) with the aim of producing a conductive copolymer for all-solid-state potentiometric chemical sensor applications. The crosslinked elastomeric polyurethane obtained was characterized by Fourier transform infrared attenuated total reflection spectroscopy, scanning electron microscopy, tunnelling electron microscopy and atomic force microscopy. Doping of lignin-based polyurethane with MWCNTs produced a significant enhancement of its electrical conductivity without deterioration of thermal and viscoelastic properties. The polymer composite displayed a low percolation threshold at an MWCNT concentration of 0.18% (w/w), which was explained by the oriented distribution of MWCNTs along lignin clusters. All lignin-based polyurethanes doped with MWCNTs at concentrations above the percolation threshold are suitable for sensor applications. Copyright © 2012 Society of Chemical Industry

Polymer Functionalized Carbon nanotubes for sensor application

ABSTRACTSurface modification of carbon nanotubes with polyvinyl alcohol (PVOH) showed detection for humidity variation implying a possible application as a nanoscale humidity sensor. Wettability studies on single-wall, Y junction single wall and multiwall carbon nanotubes revealed that these nanotubes tend to become highly hydrophilic surfaces by this functionalisation. From the raman analysis it was determined that the majority of the nanotubes in our Y-junction single wall nanotubes were semiconducting in nature. The conductivity studies revealed that the Y junction nanotubes with PVOH functionalisation show large change in conductivity for varying relative humidity (RH). We propose a possible charge transport mechanism in these functionalized nanotubes.