Passive RFID-Based Diaper Moisture Sensor

Low-energy battery-less passive RFID (Radio Frequency Identification) tags will be an integral part of the upcoming IoT (Internet of Things) revolution. Applications for such tag-systems include medical applications, inventory management, security, localization, household application, etc. Currently, there is a growing demand for passive RFID-based diaper moisture sensors in the market. The target populations for such technology include infants, disabled individuals, and senior citizens. The goal of the moisture sensor is to eliminate the risks related to infection and other issues caused by the failure to remove a wet diaper in a timely manner. Desired characteristics of such a sensor include low cost, easy integration, good dynamic range in sensing metric, a long read range, as well as being comfortable to the wearer. We propose a passive UHF (Ultra High Frequency, 902-928 MHz) RFID-based diaper moisture sensor that is low-cost, user-friendly, reusable, washable, environment-friendly and comes with an extended on-body read range of 3.6 meters with baby diapers and 4.4 meters with adult diapers. The external reader unit is connected to the internet or a local network, and will automatically notify the parents or caregivers as soon as the presence of moisture is detected.