NOVELTY - The system i.e. necklace-shaped body-worn physiological sensor (30), has a data processing system for operating a set of computer algorithms to process an impedance signal, an ECG signal and a motion signal. A wireless transmitter is integrated within a loop-shaped unit and in electrical contact with the data-processing system, and transmits processed values of the impedance signal, the ECG signal and the motion signal. A battery system powers an impedance measuring system, an ECG measuring system, a motion measuring system, the data processing system and the wireless transmitter.    USE - System i.e. necklace-shaped body-worn physiological sensor, for measuring physiological signals from an ambulatory patient to treat congestive heart failure diseases i.e. cardiac arrhythmias, using implanted devices e.g. pacemakers and implantable cardioverter-defibrillators, during electrophysiology procedures by physicians. Uses include but are not limited to a hospital, medical clinic, nursing facility and an eldercare facility.    ADVANTAGE - The system allows necklaces to be familiar to the patient wearing the sensor so as to improve compliance in making measurements as directed by a physician to improve a patient's physiological condition. The system allows a sensor's form factor to ensure consistent electrode placement for impedance and ECG measurements so as to minimize day-to-day errors associated with the electrode placement. The system allows the sensor's form factor to distribute electronics around a patient's neck, thus minimizing bulk and clutter associated with the components and making the sensor to be more comfortable to the patient. The system allows circuit boards to be potted with protective material i.e. silicone rubber, to increase patient comfort and protect underlying electronics.    DETAILED DESCRIPTION - The loop-shaped unit is a continuous flexible loop-shaped unit.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a necklace-shaped sensor that measures cardiac output, stroke volume, fluid levels, ECG waveforms, heart rate, arrhythmias and motion/posture/activity level from an ambulatory patient.    Micro-USB port (25)    Necklace-shaped body-worn physiological sensor (30)    Electrode patches (35, 37)    Electronic module (36)    Flexible flat cable (38)