Passive detection device of events

Passive detection device of events. With no power consumption until an alarming event takes place, since it takes advantage of the phase transition from a PCM (2) material (phase change material) to monitor relevant physical/chemical events. If the PCM material (2) is ion conductor, the device comprises a liquid-activated battery (1), a PCM (2) non-ion conductor, located in contact with the battery activated by liquid (1), and a Electronic module (4), connected to the battery activated by liquid (1), which is activated with the battery. If the PCM (2) material is a PCM (2) non-ion conductor, the device further comprises an ion conductive liquid, and wherein said PCM (2) non-ion conductor is located as a barrier between the conductive liquid of ions and the battery activated by liquid (1).