Patent ID: 8236164

Claim:
A moisture sensor for measuring moisture in a building, comprising: a flexible carrier for attaching said sensor to a floor or inner wall of a building; a resonant circuit printed on said carrier; a first antenna printed on said carrier, arranged to receive an electromagnetic signal within a first frequency range of 9 kHz to 11 MHz to convert said signal into an AC voltage, the AC voltage being arranged to alternate within said first frequency range; and to feed said voltage to said resonant circuit, said first antenna being further arranged to emit an electromagnetic signal indicative of an impedance of said resonant circuit; and an encapsulation layer sealing said moisture sensor, the encapsulation layer comprising a humidity permeable portion; wherein said resonant circuit comprises a moisture reactive element comprising: a first and a second inert electrode comprising electrochemically substantially inert material, each electrode being arranged as a layer, and a hygroscopic solid electrolyte arranged as a layer and spatially between said first and second inert electrodes, the hygroscopic solid electrolyte, at least in the presence of moisture, forming mobile ions selected from a group consisting of cations and anions, and the hygroscopic solid electrolyte providing a complex impedance at least in response to said alternating voltage being applied across said first and second inert electrodes.