Positive and negative dielectrophoretic collection of colloidal particles using interdigitated castellated microelectrodes

An interdigitated castellated microelectrode geometry has been found to facilitate particle collection arising from both positive and negative dielectrophoretic effects. These two forms of particle collection differ significantly as functions of the frequency of the applied non-uniform electric field and of the conductivity of the suspending medium. This behaviour is demonstrated for yeast cells and a theoretical explanation is presented in terms of the electric field patterns generated by the electrodes, as well as through consideration of the associated phenomenon of electrorotation.