Acoustic streaming in a channel with sharp edges for particle manipulation

Acoustic streaming in a sharp edge pattern channel provides an effective approach for particle manipulation in microfluidics. In this study, the flow dynamics of sharp edge acoustic streaming are first analyzed. Then, the forces acting on particles inside the channel are evaluated to identify the key mechanisms of particle manipulation. A periodic flow of controlled amplitude att frequency = 500 Hz is prescribed within the channel, in the longitudinal direction. Experiments with particles of three diameters (d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> = 1.1 µm, 5.0 µm and 10.1 µm) revealed that the larger particles d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> = 10.1 µm and d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> = 5.0 µm are concentrated near the sharp edge region where strong vortices are present, with faster collection for larger sizes. In contrast, smaller particles d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> = 1.1 µm could not be collected under the same conditions. These findings demonstrate the potential feasibility of low frequency sharp edge acoustic streaming for size-selective particle manipulation.