Self-writing smart labels for humidity monitoring

•Lateral anodic oxidation is a recent sensing and display technique.•We describe smart labels that can display the maximum relative humidity over a period of time.•The behavior of the humidity-monitoring smart labels was examined under test conditions with diverse relative humidities. Lateral anodic oxidation is a recent display technique with potential usage in self-writing smart labels and switching applications, which have the ability to operate with established RFID units. This process requires water to operate, which is harvested by a hygroscopic electrolyte layer from the ambient atmosphere. This precondition enables the realization of a humidity monitoring functionality. We develop smart labels displaying the maximum relative humidity during a period of time by the usage of halides providing different hygroscopicity in the electrolyte layer. Therefore we investigate the behavior of the humidity monitoring smart labels under test conditions with diverse relative humidity.