A plunger head for a fluid injection device includes a transducer disposed in the plunger head to measure a compressive force when applied to the plunger head. The plunger head also includes a power source and a microcontroller disposed in the plunger head. The microcontroller is coupled to the power source and the transducer, and the microcontroller is coupled to enter a high-power mode in response to sensing application of the compressive force to the plunger head.
