Effect of low frequency electric field parameters on chain formation of ZnO nanoparticles for gas sensing applications

Abstract

In present study, the effect of low frequency electric field parameters on pearl chain formation (PCF) behavior of ZnO nanoparticles was investigated using co-planar electrodes. The optical microscopy images of the deposition patterns obtained at the frequency range of 1 Hz-10 kHz revealed that below 10 kHz, Coulomb force, unsteady-state fluid flow and Alternating-electro-osmotic phenomenon dominate the deposition process preventing directional assembly of particles into chains. However, at 10 kHz the ZnO nanoparticles were observed to form chainlike patterns along the electric field lines bridging the interelectrode gap which was attributed to the dielectrophoresis force. The optimized PCF conditions were then employed to fabricate a CO gas sensor which showed a clear response to the target gas at 400°C, 450°C and 500°C. The porous layer obtained at 10 kHz also showed higher response to 3-17 ppm of NO 2 at 250°C-500°C which was attributed to easier gas flow through the layer and more reaction area compared with the dense film made using the sedimentation technique. © 2012 The American Ceramic Society.