Acoustic micromanipulation in a microchannel

Using a standing wave field of ultrasound, it is possible to trap and manipulate small objects at nodes of a sound pressure distribution. In the present paper, a sound wave was generated by a transducer far from a microchannel, and propagated into a microchannel on a glass plate, where it generated a standing wave field. When the liquid water containing alumina particles was injected into the microchannel, the particles flowed along several layers in the flat microchannel. It was shown that the traveling wave was transmitted into the microchannel and the standing wave field was formed in the microchannel. When a half circular space and a branched microchannel were added in the center of the microchannel and the frequency of the ultrasound swept, the exit channel of the particle flow can be selected.