Dielektrophoretische Untersuchungen an biologischen Systemen

The effect of nonuniform alternating fields on neutral or charged particles is named dielectrophoresis in contrast to the action of a uniform steady field on charged particles, named electrophoresis. Dielectrophoresis exhibits e.g. collection of the cells at the electrodes, pearl chain formation everywhere in the experimental chamber, cord formation with ramification, orientation of asymmetric cells, rotation and membrane fusion. In the presented experiments frequencies between 100 Hz and 5 MHz and voltages up to 70 V between electrodes of a few millimeter distance were applied to yeast cells. Dielectrophoresis may offer an interesting biophysical and microbiologic tool for collecting cells and discriminating between living and dead ones, for investigation of influence of drugs on the status of cells, for experiments on membrane or cell fusion and for the study of surface charges in different cells. Its biologic application has just begun.