In most screening scenarios, the whole cell configuration of the patch clamp method is preferable since currents are larger and the channel proteins behave in a more physiologically relevant manner than in other configurations. A whole cell preparation demands that physical or chemical disruption of the cell membrane occur only on one side of
the seal. This is done in order to minimize electrical access resistance and to optimize diffusional access to the remaining intact cell membrane.

A true whole cell configuration is achieved by applying suction pulses to the cell sealed inside a glass tip. Suction towards the tip disrupts the membrane area facing the tip. Since only individual constant suction pulses are needed instead of a feedback pressure control, automated seal and whole cell formation is reliable and reproducible without any operator action. The software monitors resistive and capacitive currents during a test pulse and controls the pressure. Typically, 1-5 suction pulses are needed for disrupting the membrane surface facing the tip opening.
The seals are very stable and seal loss during suction pulses is a rare event (<10%).