Dielectrophoretic fabrication and chacterization of ZnO nanowire-based acetylene gas sensor

Wide-gap semiconductors with nanostructures such as nanoparticles, nanorods, nanowires are promising as a new type of gas sensor. Recently, ZnO (zinc oxide) nano-structures have been extensively investigated for acetylene (C₂H₂) gas sensing device applications. In this paper, a new fabrication method of a C₂H₂ gas sensor based on ZnO nanowires using dielectrophoresis is demonstrated. Dielectrophoresis (DEP) is the electrokinetic motion of dielectrically polarized materials in nonuniform electric fields. ZnO nanowires were trapped in the microelectrode gap where the electric field became higher. The trapped ZnO nanowires were aligned along the electric field line and bridged the electrode gap. Upon exposure to C₂H₂ gas, the conductance of the DEP-trapped ZnO nanowires increased. The ZnO nanowire gas sensor response to C₂H₂ gas was dependent on the temperature and the maximum response was obtained at 250 °C. It was confirmed that the sensor response was considerably improved by electrochemically decorating the ZnO nanowires with platinum nanoparticles.