Manipulation of micro air bubbles in a flow-through cell using US standing waves

Abstract

We have developed a new method for cleaning flow-through cells by using microbubbles and ultrasonic (US) standing waves. A standing wave generated by US transducers at 1 MHz was used to trap microbubbles at node positions of the sound pressure. We were also able to control the microbubbles' positions spatially through frequency modulation. We found that these microbubbles were very effective for washing microbeads out of flow-through cells, particularly when frequency-modulated US irradiation was used. The proposed method promises to be very useful for cleaning the flow-through cells in small analytical instruments.