Abstract: A pump has an inlet opening, an outlet opening, a pump diaphragm comprising an opening, provided with a passive check valve, through the pump diaphragm, and an actuator configured to move the pump diaphragm between a first position and a second position. The passive check valve is configured such that a movement from the first position in the direction toward the second position has a closing effect, and that a movement from the second position in the direction toward the first position has an opening effect, so that a pumping cycle wherein the pump diaphragm is moved from the first to the second positions, and back, causes a net flow from the inlet opening to the outlet opening.