Particle Deflection in a Poly(dimethylsiloxane) Microchannel Using a Propagating Surface Acoustic Wave: Size and Frequency Dependence

• Published in: Analytical chemistry (Washington) Vol. 85; no. 20; pp. 9955 - 9959
• Main Authors: Skowronek, Viktor, Rambach, Richard W., Schmid, Lothar, Haase, Katharina, Franke, Thomas
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15.10.2013
• Subjects: Acoustics; Atoms & subatomic particles; Channels; Deflection; Dimethylpolysiloxanes - chemistry; Frequencies; Microchannels; Microfluidic Analytical Techniques - methods; Microfluidics; Particle Size; Physical chemistry; Propagation; Surface acoustic waves; Surface Properties; Symbols; Wave propagation
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac402607p

We study the effect of a propagating surface acoustic wave (PSAW) with different frequencies on particles with different sizes in microfluidic channels. We find that the deflection critically depends on the applied frequency as well as on the particle size. For fixed frequencies, large particles are deflected and migrate perpendicular to the flow direction while smaller particles only follow the streamlines of the flow field. However, with increasing frequency of the PSAW above a size dependent limit, small particles are also actuated. This relation can be characterized by the wavenumber k and the particle radius r using the parameter κ = k · r. For the onset of deflection, we find a critical value κc ≅ 1.28 ± 0.20. Finally, we demonstrate how this device can be used for particle separation.