This disclosure generally relates to medical devices that include a transmitter assembly positioned on top of a sensor assembly. A sensor assembly includes a sensor base having a bottom surface and a top surface having an interface. The interface accommodates a sensor stack that includes at least one sensor head having electrical contact pads connected to an elastomeric connector. The sensor assembly further includes a mounting base having a first side that attaches to the bottom surface of the sensor base, and a second side that adheres to a patient's skin. A transmitter assembly includes a transmitter shell and a transmitter cap having an interface that engages with the sensor base. Also, the transmitter assembly includes electrical contacts disposed on the transmitter cap that connect with the electrical contact pad(s) of the sensor assembly.
