Gas-sensing characteristics of dielectrophoretically assembled composite film of oxygen plasma-treated SWCNTs and PEDOT/PSS polymer

The composite film with high gas sensing capability was synthesized through dielectrophoretic assembly of nanostructured layer of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) matrix and O2 plasma-treated single-walled carbon nanotubes (SWCNTs). Characterizations of the PEDOT/PSS-SWCNTs composite were carried out by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and field emitting scanning electron microscope (FE-SEM). The results showed that oxygen-containing functional groups were grafted on the SWCNTs surface by O2 plasma treatment. The functionalized SWCNTs homogeneously dispersed in the PEDOT/PSS matrix by π–π interaction and electrostatic attraction between PEDOT chains and the nanotubes. The SWCNTs concentration affected the gas-sensing properties of the composite film via the induced morphological and conductive variation. The conductive and gas-sensing characteristics of the composite film were improved by aligning the functionalized-SWCNTs in the polymer and forming the nanostructured film surface using dielectrophoretic manipulation. The gas sensors based on the optimally dielectrophoresis-assembled composite film showed high sensitive, selective, rapid, stable and reversible responses for detection of 2–300 ppm NH3 and 6–1000 ppb trimethylamine gases at room temperature, suggesting its potential for assessing fish freshness in the fishery chain.