Patent ID: 7916035

Claim:
A sensor for an alarm intended for beds and similar locations that, e.g., old people, demented or handicapped persons are arranged to stay on and that comprises a sensor placed on the bed and coupled to a monitoring unit that is arranged to provide alarming, characterized in that the sensor, which is arranged to be placed under a mattress of the bed, is arranged to cooperate with a radio receiver, positioned remotely from the sensor, via radio communication, that the sensor is arranged to measure the difference of the capacitance of a medium in a compressed and in a free state, respectively, the sensor comprising: a compressible plastic core of a flexible, porous foam plastic material having a porous surface; a conductive gel applied to cover both sides of the plastic core and arranged to penetrate into the mass of the porous foam; and a pair of electrodes, one located on each side of the plastic core contacting the conductive gel.