A sensor assembly for an injection device comprising: a disposable label configured to be attached to the injection device, the disposable label including: an electrically conductive trace, wherein a first portion of the electrically conductive trace is configured to be altered in response to a first operation of the injection device; a reusable housing removably connected to the disposable label, the reusable housing including: a processor electrically coupled to the electrically conductive trace, wherein the processor is configured to be activated in response to an alteration of the first portion of the electrically conductive trace; and a wireless communication device configured to wirelessly communicate, to a computing device, information associated with the alteration of the first portion of the electrically conductive trace, characterized in that the processor is removably electrically coupled to the electrically conductive trace and wherein the disposable label includes a plurality of first conductive pads electrically coupled to the electrically conductive trace, wherein the reusable housing includes a plurality of spring contacts electrically coupled to the processor and removably electrically coupled to the plurality of first conductive pads, and wherein the reusable housing includes a rigid deformable clip configured to clip onto an exterior surface of the injection device. a disposable label configured to be attached to the injection device, the disposable label including: an electrically conductive trace, wherein a first portion of the electrically conductive trace is configured to be altered in response to a first operation of the injection device; a reusable housing removably connected to the disposable label, the reusable housing including: a processor electrically coupled to the electrically conductive trace, wherein the processor is configured to be activated in response to an alteration of the first portion of the electrically conductive trace; and a wireless communication device configured to wirelessly communicate, to a computing device, information associated with the alteration of the first portion of the electrically conductive trace, characterized in that the processor is removably electrically coupled to the electrically conductive trace and wherein the disposable label includes a plurality of first conductive pads electrically coupled to the electrically conductive trace, wherein the reusable housing includes a plurality of spring contacts electrically coupled to the processor and removably electrically coupled to the plurality of first conductive pads, and wherein the reusable housing includes a rigid deformable clip configured to clip onto an exterior surface of the injection device. a processor electrically coupled to the electrically conductive trace, wherein the processor is configured to be activated in response to an alteration of the first portion of the electrically conductive trace; and a wireless communication device configured to wirelessly communicate, to a computing device, information associated with the alteration of the first portion of the electrically conductive trace, characterized in that the processor is removably electrically coupled to the electrically conductive trace and wherein the disposable label includes a plurality of first conductive pads electrically coupled to the electrically conductive trace, wherein the reusable housing includes a plurality of spring contacts electrically coupled to the processor and removably electrically coupled to the plurality of first conductive pads, and wherein the reusable housing includes a rigid deformable clip configured to clip onto an exterior surface of the injection device.