A few little cells that are different from the rest can have a big effect. For example, individual cancer cells may be resistant to a specific chemotherapy—causing a relapse in a patient who would otherwise be cured. In the journal Angewandte Chemie, scientists have now introduced a microfluidics-based chip for the manipulation and subsequent nucleic-acid analysis of individual cells. The technique uses local electric fields to highly efficiently “trap” the cells (dielectrophoresis).