BPCPPDYSOE21 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 14: Microfluidics and Droplets - organized by Uwe Thiele (Münster)
DY 14.1: Vortrag
Montag, 22. März 2021, 16:00–16:20, DYa
Near-field acoustic manipulation in a confined evanescent Bessel beam — •Pierre-Yves Gires1,2 and Cédric Poulain2,3 — 1University Grenoble Alpes, CEA LETI — 2University of Bayreuth, Experimental Physics I — 3University Grenoble Alpes, CNRS, Grenoble INP, Institut Néel
Microparticles such as cells can be manipulated in a suspension by the application of an ultrasonic acoustic field. Following the path taken in the development of optical tweezers, we demonstrate the potential of working in the evanescent regime, with both sub-wavelength confinements and resonators [1]. We generate an evanescent acoustic Bessel beam in liquid above a thin, circular, axisymmetrically excited plate. In the sub-MHz domain, the resulting radiation force causes the particles to assemble at the pressure antinodes along concentric circles corresponding to the Bessel profile. By imposing an axial confinement in the evanescent region, the sub-wavelength two-plate sandwich system becomes resonant, increasing the radiation force magnitude. Resonances occur for some well-defined gaps for which whole numbers of antinodal circles are observed. Through fine tuning, particles as small as bacteria can be patterned. Further amplification can be obtained by trapping a microbubble in the Bessel beam axis. [1] Pierre-Yves Gires and Cédric Poulain. Near-field acoustic manipulation in a confined evanescent bessel beam. Communications Physics, 2(1):1-8, 2019