The method for controlling the downstream progress of a liquid in a microfluid component, comprising, for example, a number of microchannels, each having a number of successive reaction or detection zones and a number of passive valves, controls the progress of the liquid in the microchannels by controlling the increase of pressure differential between the upstream and downstream end of the component. The method controls the increase in pressure differential in a discontinuous manner in the form of release pulses (Pd), such as to particularly synchronise the passage through the corresponding passive valves in the microchannels. The pressure difference is reduced to a zero value between two successive release pulses (Pd).