A method and system of universal, secure attachment with attachment detection mechanism, of a wearable sensor-unit to any article of clothing worn around the body in order to measure vital signals of a person, such as motion, movements and activity levels. The method and system permits: reliable attachment to any article of clothing； an attachment in any position to clothing or fabric worn by a person； and detection for the wearable sensor attachment to an article of clothing to minimize false alarms.
