On-die actuator evaluation

A method comprising:

• receiving an activation pulse for activating an actuator of a primitive on a fluid ejection die;
• activating the actuator based on the activation pulse to generate a first voltage measured at a corresponding actuator sensor, wherein the corresponding actuator sensor:
• is disposed in an ejection chamber on the fluid ejection die;
• and
• is coupled to the actuator;
• and
• evaluating an actuator characteristic of the actuator at an actuator evaluation device shared by multiple actuators of the primitive and disposed on the fluid ejection die based at least in part on a comparison of the first voltage and a threshold voltage.

A fluid ejection system comprising:

• multiple fluid ejection dies, wherein a fluid ejection die comprises:
• a number of actuators to manipulate fluid, wherein the number of actuators:
• are disposed on the fluid ejection die;
• and
• are grouped as primitives on the fluid ejection die;
• and
• a number of drive bubble detection devices, wherein each drive bubble detection device is:
• coupled to one of the number of actuators;
• and
• a single electrically conductive plate disposed between an actuator and a fluid channel;
• an actuator evaluation device disposed on the fluid ejection die to determine when a nozzle associated with the actuator is blocked based at least in part on a comparison of an output of a corresponding drive bubble detection device and a threshold voltage;
• and
• a transistor to selectively couple the actuator evaluation device to a selected drive bubble detection device.