Surface acoustic wave controlled integrated band-pass filter
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We introduce a microfluidic band-pass filter for particles that is fully integrated in a polydimethylsiloxane-based microchannel device. This acoustic filter allows a continuous and label-free separation of particles. To demonstrate the functionality, mixtures of particles with different sizes are exposed to propagating surface acoustic waves generated by two laterally displaced interdigitated transducers, one on each side of the microchannel. Dependent on the frequency used, a specific size or even a size range of particles can be extracted. We sort particles of sizes of ~1–10 µm and estimate the size resolution to be smaller than ∆r < 0.88 µm. We examine the performance of the device and achieve a throughput of ~105 particles/s with an efficiency as high as 99 %.
KeywordsBand-pass filter SAW Propagating surface acoustic waves (PSAW) Sorting Microfluidics PDMS Particle separation Particle filtering
The authors thank Achim Wixforth for support and acknowledge support by the Center for NanoScience (CeNS). V. S. and R. R. thank Lothar Schmid and Thomas Geislinger for discussions. T. F. thanks the German Research Foundation (DFG) for financial support via priority programs and research grants. R. R. and T. F. acknowledge support by the “Bayerisches Staatsministerium für Umwelt und Verbraucherschutz”.