Analytical scale ultrasonic standing wave manipulation of cells and microparticles

The ultrasonic standing-wave manipulation of suspended eukaryotic cells, ba cteria and submicron latex or silica particles has been examined here. The different systems, involving plane or tubular ultrasonic transducers and a range of acoustic pathlengths, have been designed to treat suspension volum es of analytical scale i.e. 5 ml to 50 mu l for both sample batch and 'on-l ine' situations. Frequencies range from 1 to 12 MHz. The influence of secon dary cell-cell interaction forces in determining the cell concentration dep endence of harvesting efficiency in batch sedimentation systems is consider ed. Applications of standing wave radiation forces to (1) clarify cell susp ensions, (2) enhance particle agglutination immunoassay detection of cells or cellular products and (3) examine and enhance cell-cell interactions in suspension are described. (C) 2000 Elsevier Science B.V. All rights reserve d.