Abstract: A system for detecting wetness in diapers for the propose of calling the attention of a caretaker. The system is based on the nonlinear interaction of an implanted device inside the diaper with a low distortion background electromagnetic field. The background field is generated by a transmitter external to the diaper. The device is a combination of an antenna, a nonlinear element and two electrodes. Upon a wet condition the resistance between the two electrodes decrease, resulting in an increase in coupling between the antenna and the nonlinear element. The ensuing nonlinear interaction between the antenna and the background field gives rise to harmonics of the field which are detected by a receiver. The receiver which is also external to the diaper triggers a suitable alarm.