Abstract

A fluid ejection apparatus is disclosed including a trough having side walls and an exposed roof the trough being substantially filled with fluid; a paddle vane located within the trough and offset from one wall when the paddle vane is in a quiescent position; an actuation mechanism attached to the paddle vane such that, upon activation of the actuation mechanism, the paddle vane is caused to move towards the one wall, resulting in an increase in pressure in the fluid between the one wall and the paddle vane, resulting in a consequential ejection of fluid via the exposed roof. Ideally, the present invention can be utilized in an ink jet printing system. The actuation mechanism can be interconnected to the paddle vane via an arm extending over one edge of the exposed roof and the actuation mechanism can comprise a coiled thermal actuator having a first conductive arm and a second substantially non-conductive arm, the conductive arm expanding upon electrical resistive heating to thereby cause the actuation of the thermal actuator. The first conductive arm can comprise substantially titanium diboride and the second non-conductive arm can comprise substantially silicon nitride. The actuation mechanism can operate in the ambient atmosphere.