Abstract: A sensor device for sensing wetness in an absorbent article worn by a subject includes one or more sensing elements; and a coupling for communicating sensor signals between the one or more sensing elements and a receiver. A change in environmental parameter causes a change in electrical behaviour of at least one of the sensing elements, which behaviour can be analysed to determine occurrence of a wetness event in the absorbent article. The changes in electrical behaviour are communicated in the sensor signals to the receiver. The analysis may be by the receiver or a processor in communication with the receiver. Ideally, the sensing elements include capacitive elements and preferably, resonance circuits.