Abstract: A micro electro-mechanical device embodied within an ink ejection nozzle having an actuating arm that is caused to move an ink displacing paddle when heat inducing electric current is passed through the actuating arm is disclosed. The paddle is located in an ink chamber and the actuating arm passes through an actuator aperture in the chamber. The chamber is partly defined by a cylindrical part circular concave edge portion on an upper wall of the ink chamber. The actuating arm carries a second cylindrical wall which covers the actuator aperture and which registers in the part circular concave edge portion. The second cylindrical wall is moveable relative to the edge portion when the actuating arm and paddle are moved to eject a droplet. Upon movement of the actuating arm the second wall moves relative to the edge portion and a meniscus is created between the edge portion and the second wall which forms a seal between the second wall and the edge portion of the chamber wall.