Acoustophoresis of hollow and core-shell particles in two-dimensional resonance modes

• Published in: Microfluidics and nanofluidics Vol. 16; no. 3; pp. 513 - 524
• Main Authors: Leibacher, Ivo, Dietze, Wolfgang, Hahn, Philipp, Wang, Jingtao, Schmitt, Steven, Dual, Jürg
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2014; Springer; Springer Nature B.V
• Subjects: Analytical Chemistry; Biological and medical sciences; Biomedical Engineering and Bioengineering; Biotechnology; Engineering; Engineering Fluid Dynamics; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Nanotechnology and Microengineering; Research Paper; Resonance; Standing waves; Various methods and equipments; Ultrasonic particle manipulation; Acoustofluidics; Core-shell particles; Gor’kov potential; Acoustophoresis; Fluid mechanics; Core shell structure; Particle motion; System on a chip; Experimental study; Hollow shape; Gor'kov potential; Test facility; Acoustic radiation; Microparticle; Particle shape; Micromanipulation; Microfluidics; Ultrasonic method
• ISSN: 1613-4982; 1613-4990
• DOI: 10.1007/s10404-013-1240-7

Motivated by the applications of ultrasonic particle manipulation in a biotechnological context, a study on acoustophoresis of hollow and core-shell particles is presented with analytical derivations, numerical simulations and confirming experiments. For a long-wavelength calculation of the acoustic radiation forces, the Gor’kov potential of hollow, air-filled particles and particles with solid or fluid core and shell is derived. The validity as well as the applicable range of the long-wavelength calculation is evaluated with numerical simulations in Comsol Multiphysics ® . The results are experimentally verified in the acoustic field of an intrinsically two-dimensional fluid resonance mode, which allows for a more complex analysis than the common one-dimensional ultrasonic standing waves or their superposition to two-dimensional fields. Experiments were conducted with hollow glass particles (13.9 μm diameter) in a microfluidic chamber of 1.2 mm × 1.2 mm × 0.2 mm on a silicon-based device with piezoelectric excitation around 870 kHz. The described resonance mode is of additional interest for particle trapping and medium exchange on certain particle types, and it reveals a novel approach for particle characterization or separation.