We developed a novel active micromixer that uses a driving electrical voltage and combines a microchannel and nanojunction. The microchannel was fabricated using the general soft lithography process with polydimethylsiloxane (PDMS). The nanojunction was created at a specific position on the microchannel by using the breakdown of PDMS due to the application of high electrical voltage. The proposed micromixer efficiently mixed two fluid streams by the combined effects of bulk electro-osmotic flow and vortical flow created by the non-equilibrium electrokinetic effect near the nanojunction. The proposed micromixer achieved up to 90% mixing of the two fluid streams, and could be easily integrated with other microfluidic components due to its planar structure and simple fabrication process. (C) 2012 Elsevier B.V. All rights reserved.