A system for wirelessly obtaining physiological data from a subject includes a sensor patch and a separate electronics package. The sensor patch is disposed on and adheres to the subject, and includes a first part of a releasable electrical connector. An electronics package includes a second part of the first releasable electrical connector, which is used to physically and electrically connect the electronics package to the sensor patch. The electronics package includes a flexible substrate, with shells set on this substrate. The shells enclose the electronics. The shells are connected by a flexible circuit board. Analog front end circuitry is placed in one shell, while the wireless transceiver is placed in the other shell.
