Movable ink ejection structure and inverse profile actuator arms for nozzle arrangement

1. A nozzle arrangement for an ink jet printhead, the nozzle arrangement comprising:

a wafer substrate arrangement defining an ink inlet channel and a first wall surrounding the ink inlet channel;

a movable ink ejection structure defining an ink ejection port and a second wall surrounding the first wall so that the wafer substrate arrangement and ink ejection structure together define a nozzle chamber in fluid communication with the ink inlet channel and the ink ejection port; and

a plurality of thermal bend actuators movably coupling the ink ejection structure to the wafer substrate arrangement, each actuator comprising an arm for moving the ink ejection structure responsive to an applied electrical signal, whereby a volume of the nozzle chamber is varied, wherein

each arm includes a pair of inner active portions and a pair of outer passive portions, the inner active portions having a profile inverse to that of the outer passive portions.

2. A nozzle arrangement as claimed in claim 1 , wherein the outer passive portion has a profile including a central horizontally extending section interposed between a pair of outer horizontally extending sections, the central horizontally extending section being connected to the outer horizontally extending sections by a pair of substantially vertically extending sections.

3. A nozzle arrangement as claimed in claim 1 , wherein the pair of inner active portions conduct the electrical signal, and the pair of inner active portions are located between the pair of outer passive portions.

4. A nozzle arrangement as claimed in claim 1 , wherein the wafer substrate arrangement comprises:

a wafer substrate;

a drive circuitry layer positioned on the wafer substrate and electrically coupled to each arm to apply the electrical signal; and

an ink passivation layer positioned on the drive circuitry layer.