A wearable system includes a support structure with optionally one or more electrodes in an unbiased state. Different sensor modules may monitor, for the long-term, different patient parameters such as the patient's motion, a physiological parameter, a patient sound etc., other than the patient's ECG. The sensor modules can be worn by the patient concurrently, or only one at a time as convenient, and may provide respective sensor signals. The system may determine from one or more of the available received signals whether a certain threshold has been reached, such as when the patient is having an actionable episode. If so, at least one electrode may become mechanically biased against the patient's body, for making good electrical contact. Then, an ECG reading may be taken and/or therapy may be administered.
