Pulsed-field gel electrophoresis

Pulsed-field gel electrophoresis (PFGE) is a technique used for the separation of large DNA molecules by applying an electric field that periodically changes direction to a gel matrix. The mechanism driving these separations exploits the fact that very large DNA molecules unravel and "snake" through a gel matrix, and such electrophoretic trajectories are perturbed in a size-dependent manner by carefully oriented electrical pulses.

Source: Wikipedia — Pulsed-field gel electrophoresis (CC BY-SA 4.0)