A smart diaper to be worn by a user, includes an absorption material configured to absorb to form a soiled area, a pair of electrode sensing circuits comprising a first electrode sensing circuit and a second electrode sensing circuit, which are positioned parallel to each other and are in contact with the absorbent material, wherein the pair of electrode sensing circuits can be laid out in a spatially distributed pattern across the absorption material, and a controller that can apply a voltage across the pair of electrode sensing circuits and to produce an electrical current that increases with area of the soiled area according to the spatially distributed pattern.
