A physiological data collection device (700, 1000, 1100, 1200) comprising: an electro-cardiogram lead-wire set (710, 1010, 1110, 1210); a data collection unit (705, 805, 905, 1005, 1105, 1205) comprising: a lead-wire set interface (730, 1030, 1130, 1230) for connecting to the ECG lead-wire set, a data connector (745, 1145) for connecting to an external computing device, wherein: the data connector comprises a male connector; the male connector comprises standard contacts and customized data collection unit contacts; and the lead-wire set connects to the male connector such that the lead-wire set interface interfaces with the lead-wire set via the customized data collection unit contacts in the male connector; non-volatile memory coupled with the data connector and the lead-wire set interface, and a processor (717, 1117) programmed to obtain ECG data from the ECG lead-wire set and store the obtained ECG data in the non-volatile memory; and wherein the ECG lead-wire set or the data collection unit or both have one or more structural components that prevent a connection between the data connector and the external computing device when the ECG lead-wire set is connected to the data collection unit and vice versa. an electro-cardiogram lead-wire set (710, 1010, 1110, 1210); a data collection unit (705, 805, 905, 1005, 1105, 1205) comprising: a lead-wire set interface (730, 1030, 1130, 1230) for connecting to the ECG lead-wire set, a data connector (745, 1145) for connecting to an external computing device, wherein: the data connector comprises a male connector; the male connector comprises standard contacts and customized data collection unit contacts; and the lead-wire set connects to the male connector such that the lead-wire set interface interfaces with the lead-wire set via the customized data collection unit contacts in the male connector; non-volatile memory coupled with the data connector and the lead-wire set interface, and a processor (717, 1117) programmed to obtain ECG data from the ECG lead-wire set and store the obtained ECG data in the non-volatile memory; and a lead-wire set interface (730, 1030, 1130, 1230) for connecting to the ECG lead-wire set, a data connector (745, 1145) for connecting to an external computing device, wherein: the data connector comprises a male connector; the male connector comprises standard contacts and customized data collection unit contacts; and the lead-wire set connects to the male connector such that the lead-wire set interface interfaces with the lead-wire set via the customized data collection unit contacts in the male connector; the data connector comprises a male connector; the male connector comprises standard contacts and customized data collection unit contacts; and the lead-wire set connects to the male connector such that the lead-wire set interface interfaces with the lead-wire set via the customized data collection unit contacts in the male connector; non-volatile memory coupled with the data connector and the lead-wire set interface, and a processor (717, 1117) programmed to obtain ECG data from the ECG lead-wire set and store the obtained ECG data in the non-volatile memory; and wherein the ECG lead-wire set or the data collection unit or both have one or more structural components that prevent a connection between the data connector and the external computing device when the ECG lead-wire set is connected to the data collection unit and vice versa.