This letter presents a new wireless sensor system for smart diaper application, which consists of an interrogator circuit, an antenna, and a passive LC resonating sensor tag. The wireless link between the interrogator circuit and the sensor tag is established through the inductive coupling. The wetting of the diaper shifts the resonating frequency of the sensor tag, changing the inductive link, and thus trigger an "On" or "Off" condition reflected at the interrogator circuit. With suitable sensor tags, smart diapers can be achieved in a straightforward and low cost approach. 2008 IEEE.
