Embedded multiple-part sensor within a plunger rod to capture and transmit injection information

A smart plunger rod adapted to push a medication out of a syringe is disclosed. The plunger rod comprises a shaft sized and dimensioned to act on a piston on the syringe and a finger actuated head portion containing at least two subunits of a wireless sensor. In a pre-activation configuration, the subunits are spaced apart from each other by a physical barrier and the wireless sensor is non-operational. In a post-activation configuration, the subunits are connected to each other and the sensor is operational to send a signal. A user activates the finger actuated head portion to reversibly move the physical barrier and moves the plunger rod from the pre-activation configuration to the post-activation configuration. The signal sent by the sensor comprises information relating to ejecting the medication out of the syringe, and is received by a remote receiver.