Apparatus comprising fluids guiding means and process for using such apparatus

Device has at least one first channel (4) that can be subjected to a first fluid, at least one second channel (1) that can be subjected to a second fluid and at least one elastically deformable dividing wall (8) arranged between the first and second channels. Dividing wall deformation can be controlled externally by the first channel, whereby a pressure in the first channel or a pressure difference between the channels acts as a control parameter. An independent claim is also included for: (a) a method of operating an inventive device with an arrangement for guiding fluids.