Lab-on-chip (LoC) based on dielectrophoresis for liquid biopsy (LB) is described. LoC-LB operated near cross-over frequency of circulating tumor cells. LoC-LB does not require focusing which reduces complexity. LoC-LB realized using standard microfabrication processes. LoC-LB tested using a suspension of MDA-MB-231 and regular blood cells.