A new mechanism for generating a micron-sized bubble jet in an electrolyte within a micro-fluidic device is reported. A three-dimensional electrode tip is placed at the center of a micro-channel. All but the electrode tip is insulated with a dielectric film. A counter insulated electrode sits across the tip electrode and a large high-frequency (> 100 kHz) and high intensity (>1000 V) AC field is applied across the electrodes. The large voltage generates micron-sized bubbles at the tip which snaps off intermittently or continuously to produce a micro-bubble jet by a unique tip streaming mechanism. The ejected bubbles continue to be driven by an electrostatic force in the tip direction and move at a velocity in excess of 10 cm/sec. They drag a large surrounding liquid column around them to move at the same velocity and hence generate a pumping action stronger than all reported electro-kinetic micro-pumps.

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