Schematic of an envisioned microfluidic mixing system using an alternating current electrowetting-on-dielectric (AC-EWOD)- driven mobile oscillating bubble: (a) Initial state; (b) When a voltage is applied to the top ground electrode and the bottom electrodes where a bubble sits, the bubble oscillates and simultaneously generates a microstreaming flow. Neighboring microparticles are stirred and mixed by the flow; (c) When the oscillating bubble is transported to the right by sequentially activating the array of EWOD electrodes, the microstreaming flow from the bubble is stirring and mixing microparticles through the entire microfluidic chip; (d) the initially gathered microparticles in the left side are widely spread over the entire area in the microfluidic chip.