Micron-sized particles easily pass through a polymer mesh filter with
pores averaging a few millimeters across. But when an acoustic signal
is turned on, the tiny particles are trapped by a complex pattern of
standing sound waves. In effect, the acoustic field allows a coarse
filter to capture particles as efficiently as a much finer filter, without
the corresponding impedance to fluid flow usually associated with small
pores. When the field is switched off, the particles are rapidly swept
out of the filter mesh.
Reported by: Donald
Feke, 73rd Annual Society of Rheology meeting
in Bethesda, Maryland, October 22-25, 2001.
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