The present invention relates to a gas supply system (10) for a patient interface (30) for supplying a flow of pressurized gas to a subject (50), an according patient interface (30) with such a gas supply system (10) and a therapy device with such a gas supply system. The gas supply systems according to the present invention comprise a pump device (55) that has at least one membrane (58) for pumping actuation. This membrane (58) is actuated via an electro-active polymer material (60).