Clarification of plasma from whole human blood using ultrasound

There has been interest for a number of years in the possibility of separat ing blood into cells and plasma by methods other than centrifugation, so th at the plasma can be analysed on-line. Cells in whole blood normally occupy about 45% of the suspension volume. It has been shown with a number of dif ferent cell types, such as yeast and bacteria, that for concentrations of t his order the cells are not as efficiently harvested by ultrasound as those for lower concentrations. In this study, removal of cells from 3-4 mi whol e blood volumes has been examined in ultrasonic standing wave fields from t ubular transducers driven at a frequency of 1.6 MHz. Samples of whole human blood (n=11) from two volunteers have been processed by three tubular tran sducers where high levels of cell removal, 99.7% on average, have been demo nstrated with high reproducibility between samples as well as for different transducers. (C) 2000 Elsevier Science B.V. All rights reserved.