Integrated circuit fluid ejection device

A fluid ejection device which comprises

• a substrate;
• nozzle chamber walls arranged on the substrate and defining a plurality of nozzle chambers, the substrate defining a plurality of fluid inlet channels in fluid communication with the nozzle chambers to supply fluid to the nozzle chambers;
• drive circuitry arranged on the substrate;
• and
• a plurality of micro-electromechanical devices positioned on the substrate, each device comprising:
• an elongate actuator having a fixed end that is fast with the substrate so that the actuator is connected to the drive circuitry and a working end that is displaceable along a path relative to the substrate to perform work, the actuator including a pair of elongate arms that are spaced relative to each other along the path and are connected to each other at each end, with one of the arms being connected to the drive circuitry to define a heating circuit and being of a material that is capable of expansion when heated, such that, when the heating circuit receives an electrical signal from the drive circuitry, that arm expands relative to the other to deform the actuator and thus displace said working end along said path;
• and
• a fluid displacement member that is fixed to the working end of the elongate actuator and is positioned in a respective nozzle chamber so that displacement of the working end and thus the fluid displacement member results in the ejection of fluid from the nozzle chamber.