A sensor that is sensitive to the presence of aqueous-based fluids is described. The sensor has a wetness indicating material immobilized or printed on a substrate. The indicating material contains at least one electron-donating leuco dye and one electron deficient receptor, and exhibits a visual signal (e.g., vivid or strong color intensity) in a dry state, which fades or disappears when in contact with a water-containing liquid. An absorbent article incorporating such a sensor to communicate to a user that the article has been exposed to water-containing fluids is also described.
