Microfluidics with ultrasound-driven bubbles

Microstreaming from oscillating bubbles is known to induce vigorous vortex flow. Here we show how to harness the power of bubble streaming in an experiment to achieve directed transport flow of high velocity, allowing design and manufacture of microfluidic MEMS devices. By combining oscillating bubbles with solid protrusions positioned on a patterned substrate, solid beads and lipid vesicles are guided in desired directions without microchannels. Simultaneously, the flow exerts controlled localized forces capable of opening and reclosing lipid membranes.