1. A system for passively monitoring multiple patients, the system comprising: a plurality of sensor devices, each sensor device comprising: a surface for coupling with a patient; and at least two piezoelectric sensors coupled with the surface for sensing at least one mechanical signal from the patient, each of the sensors comprising a piezoelectric film; a plurality of processors, each processor coupled with one sensor device and being operative for converting the at least one mechanical signal into at least one digital signal and for analyzing the digital signals corresponding to each of the at least two piezoelectric sensors to select the sensors with the highest quality heart rate and respiration rate signals to use for deriving heart rate and respiration rate data pertaining to the patient; and at least one connector coupled with each processor for connecting each processor with a common alarm system for providing an alarm based on heart rate and/or respiration rate criteria for each of the multiple patients to a user at a remote location.