title: Microparticle column geometry in acoustic stationary fields.
abstract: Particles suspended in a fluid will experience forces from stationary acoustic fields. The magnitude of the force depends on the time-averaged energy density of the field and the material properties of the particles and fluid. Forces acting on known particles smaller than 20 microm were studied. Within a 500 kHz acoustic beam generated by a plane-piston circular source, observations were made of the geometry of the particle column that is formed. Varying the acoustic energy altered the column width in a manner predicted by equations for the primary acoustic radiation force from scattering of particles in the long-wavelength limit. The minimum pressures required to trap gas, solid, and liquid particles in a water medium at room temperature were also estimated to within 12%. These results highlight the ability of stationary acoustic fields from a plane-piston radiator to impose nano-Newton-scale forces onto fluid particles with properties similar to biological cells, and suggest that it is possible to accurately quantify these forces.
authors.affiliation: Department of Biomedical Engineering, University of California, One Shields Avenue, Davis, California 95616-5294, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hancock
authors.forename: Michael F
authors.initials: MF
authors.lastname: Insana
authors.forename: John S
authors.initials: JS
authors.lastname: Allen
mesh_terms: D000162:Acoustics; D006112:Gravitation; D008432:Mathematical Computing; D009038:Motion; D014159:Transducers