Gesellschaft zur Förderung von Medizin-,
Bio- und Umwelttechnologien e. V.

Erich-Neuß-Weg 5 trenner 06120 Halle (Saale)
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Separation processes like filtration, sedimentation, flocculation or centrifugation use gravimetrical or inertial forces and density differences as fractionating criteria. In many cases the filtrate, particularly animal cells, irreversible damaged by coagulation. Fouling of membranes affect their separation function and raise up the question of their proper use in cell culture technique.

Little known is the separation of micro particles with acoustic forces (s. Fig 1). Particles within an acoustic field are exposed to time averaged radiation forces. Due to standing waves this forces can be used to manipulate and concentrate the particles in the surrounding media. Fig. 1 shows the concentration of hollow glass spheres. The inducing acoustic field is generated by piezo rings exciting the pipewall in radial direction (Fig.2). This approximately results in a one dimensional pseudo standing wave field.

The time dependent acoustic pressure field is produced in a symmetric cylindrical configuration with two transducers excited with the same amplitude but antipodal directioned phase velocity.

The transducers oscillate with less different frequencies. This allows the directed transport of particles with different velocities and directions. The direction of motion is chosen thus the difference of both freqencies is positive or negative.

Topics of Research
  • Establishing mathematical models and simulation of different geometric configurations of oscillating elements (piezoactors, transducers, sound propagation in passive materials)
  • Adaption of the acoustic separation principle to separation and manipulation of cells (e.g. optical microscopy) and culture preparation (touchless separation)