term1 ultrasonic levitator

The ultrasonic levitator use the ultrasonic wave to levitate single particles or droplets. It suspends the levitated object contactlessly in a fixed position.

As a result of multiple reflections between an ultrasonic radiator and a solid, flat or concave reflector - which is adjusted concentrically at a distance of some multiple half wavelengths - a standing wave with equally spaced nodes and anti nodes of the sound pressure and velocity amplitude will be generated. Solid or liquid samples with effective diameters of less than half a wavelength will be levitated without contact below the pressure nodes as a result of axial radiation pressure and radial Bernoulli stress.

The ultrasonic levitator consists of the reflector flange with integrated concave reflector and a micrometer screw for the variation of the reflector distance, and the transducer flange with integrated ultrasonic transducer, shielding tube and round socket. Generally, it has a micrometer adjustment screw, a piezoelectric sensor connector, a piezoelectric sensor, a reflector, an ultrasound transducer, an absorber and a HF-connector.

Some key points:
1. The distance of the radiator and reflector is some multiple half wavelengths.
2. Solid or liquid samples with effective diameters of less than half a wavelength will be levitated.
3. The self-excitation of sample oscillations can be prevented by tilting the levitator axis by approximately 10-15 degree.
4. The levitator should be mounted on a base plate.
5. Increase reflector distance about 0.2mm above the optimum, in order to avoid possible self-excitation of sample oscillations.