Size selection of levitated aerosol particulate in an ultrasonic field.

The ability to characterize and manipulate micron-size aerosols and particulate is useful for applications in medicine, environmental monitoring, and chemical-biological defense. An experiment was conducted to determine the effects of ultrasonic frequency on the size-selectivity of concentration of polyglycol aerosols that are entrained in air within an ultrasonic resonator. Measurements of aerosol concentration at 4, 25, and 40 kHz were compared with theoretical predictions based on one-dimensional models for radiation pressure and asymmetric Stokes drag effects. The experimental results are shown to be consistent with theory.