A sensor for indicating moisture, comprising a unit whose conductivity is dependent on the current moisture exposure and an electric circuit, the unit being included as a component in the electric circuit and the electric circuit being activable by applying an electric field and/or a magnetic field over the same to generate a measurable signal, which is dependent on the total resistance of the circuit. The unit comprises an enzyme together with a substrate, which enzyme is activated when moisture exposure occurs to catalyse a reaction with the substrate that is dependent on the degree of moisture exposure, the substrate reaction product increasing the conductivity of the unit. The invention also relates to the use of such a sensor and a method of using a sensor to indicate moisture.