Devices, systems and methods provide passive patient monitoring of such parameters as body motion, body position, respiratory rate and/or heart rate. Passive monitoring generally involves a sensor device having at least two piezoelectric sensors, provided on a surface, such as a bed, chair, operating table or the like, so that a patient may be coupled with the device by simply allowing the patient to lie, sit, lean, stand on or wear the surface. In one embodiment, multiple patients in a general care area of a hospital may be continuously monitored via multiple passive monitoring devices. If a patient fails to meet one or more predefined threshold criteria or has a negative physiological trend, the system may activate an alarm.