Dynamics of magnetic bubbles in acoustic and magnetic fields.
We report on shelled bubbles that can be manipulated with magnetic fields. The magnetic shell consists of self-assembled magnetic nanoparticles. The magnetic susceptibility of the bubbles is proportional to the surface area, chi_{b}=(9+/-3x10;{-6} m)r;{2} where r is the radius. Magnetic bubbles are compressible in moderate acoustic fields. A bubble with a radius of 121 mum oscillates in resonance in a sound field of 27 kHz with a peak-to-peak radial amplitude of 1.7 mum. The bubble oscillations induce a microstreaming flow with a toroidal vortex at the upper pole of the bubble. Further findings are the longevity of the magnetic bubbles and the ease of manipulation with standard magnets.
Zhao
Xue
X
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
Quinto-Su
Pedro A
PA
Ohl
Claus-Dieter
CD
D000162:Acoustics; D004655:Emulsions / Q000737:chemistry; D008280:Magnetics / Q000295:instrumentation / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry*
D004655:Emulsions