Effect of liquid properties on the growth and motion characteristics of micro-bubbles induced by electric fields in confined liquid films

The effect of liquid properties on gas bubble growth and motion characteristics in liquid films confined within a nanogap between a highly polished steel ball and a smooth glass disc under an electric field is reported. Experimental results show that the critical voltage for the appearance of bubbles has insignificant dependence on liquid viscosity and surface tension. The bubble size after detachment increases with liquid viscosity, and bubble instability and coalescence tend to occur when bubbles move some distance away from where they were formed. An increase in liquid surface tension results in larger bubbles at the growth stage. Also, the bubble motion characteristics are greatly influenced by liquid viscosity, and the dielectrophoresis force is demonstrated to be the dominant driving force for bubble movement. Theoretical models and analyses have been used to discuss the bubble formation and describe the bubble movement characteristics.