A waste sorting robot gripper comprises a suction cup engageable with the surface of a waste object. The suction cup has an air hole for evacuating air from the suction cup. A suction tube is coupled to the suction cup. The suction tube comprises a longitudinal axis. A first air inlet is in fluid communication with the air hole at one end of the suction tube and an air outlet at the other end of the suction tube. A path of the air flow between the air inlet and the air outlet is substantially along the longitudinal axis. The suction tube comprises a second air inlet in fluid communication with an air source, the second air inlet being between the first air inlet and the air outlet.