A microfluidic device for processing a liquid in ludci includes at least one pneumatic substrate with a pneumatic cavity and a fluidic substrate with a fluidic cavity for accommodating the liquid. The fluidic cavity is arranged opposite the pneumatic cavity. In addition, the microfluidic device has a flexible membrane which is arranged between the pneumatic substrate and the fluidic substrate. The flexible membrane is designed to fluidically separate, from one another, a fluidic chamber extending at least in part in the fluidic cavity and a pneumatic chamber extending at least in part in the pneumatic cavity. The microfluidic device further includes a first pneumatic channel for applying a first pneumatic pressure to the pneumatic chamber and a second pneumatic channel for applying a second pneumatic pressure to the pneumatic chamber.