Ink jet printhead having efficient heat dissipation and removal of air

A device for selectively ejecting droplets of at least one fluid, said device comprising:

• a nozzle plate which defines a plurality of fluid-emitting nozzles;
• a heater substrate disposed adjacent and substantially perpendicular to the nozzle plate, said heater substrate having a rear surface, a front surface, a top surface, and a bottom surface, wherein the rear and front surfaces are substantially larger than the top and bottom surfaces;
• a fluid housing attached to the nozzle plate, said fluid housing including:
• a fluid inlet configured to permit a flow of fluid;
• a first internal wall which defines a fluid flow path such that fluid flows from the fluid inlet substantially around all of the rear, top and front surfaces of the heater substrate;
• an intermediate layer disposed adjacent a portion of the front surface of the heater substrate, said intermediate layer defining a plurality of fluid flow channels in fluid communication with the plurality of nozzles;
• and
• a channel cap plate disposed adjacent the intermediate layer, said channel plate capping the plurality of fluid flow channels.