Design of a textile-based UHF RFID sensor for high read range and multilevel diaper moisture sensing

Diapers are essential for managing incontinence in infants, but delayed diaper changes can lead to discomfort, skin rashes, and infections. Previous research has focused on ultra-high frequency (UHF) radio-frequency identification (RFID) moisture sensors with limited read ranges and binary (dry/wet) detection capabilities. This study proposes a textile-based UHF RFID bowtie antenna using high conductive material as a passive sensor for diaper moisture sensing. The purpose of the sensor is to detect and measure moisture levels in infant diapers, providing immediate notifications to parents and caregivers. The sensor, measuring 78 mm × 32 mm × 0.09 mm, offers multilevel wetness detection (0-60 ml) and achieves a maximum read distance of 12.1 m (dry) and 3.3 m (wet) within the US UHF RFID passband (902-928 MHz), which, to the best of our knowledge, represents the highest reported read range among passive UHF RFID diaper moisture sensors in the scientific literature. Additionally, the sensor is cost-effective, reusable, flexible, and can seamlessly attach to reusable diapers, making it an ideal solution for practical and sustainable diaper monitoring applications.