Novel cylindrical, air-coupled acoustic levitation/concentration devices

A new class of devices for levitation and/or concentration of aerosols and small liquid/solid samples (up to several millimeters in diameter) in air has been developed. The novelty of these devices is their simplicity in design. These are inexpensive, low-power, and, in their simplest embodiment, do not require accurate alignment of a resonant cavity. Best of all, these can be off-the-shelf items. The devices are constructed from a hollow, cylindrical piezoelectric tube. The main design criteria requires a resonant mode of the tube to match a resonant mode of the interior air-filled cavity. Once matched, it is shown that drops of water in excess of 1 mm in diameter may be levitated inside the cylinder cavity against the force of gravity for less than 1 Watt of input electrical power. Efficient concentration/agglomeration of aerosol particles in air is also demonstrated.