Conductive fiber-based RFID sensor for real-time urine monitoring in smart diapers

• Developed reusable RFID-textile real-time urine volume monitoring sensor. • Designed embroidered dual-tag sensor achieved 3-m urine detection range. • Prediction model had 97.5% read distance and 94.6% urine volume prediction accuracy. • Achieved health monitoring and enhanced nursing and care efficiency. Diapers are essential in daily nursing for infants, the elderly and bedridden patients. Most commercially diapers lack intelligent urine management functions, requiring users and caregivers to rely on frequent manual inspections to determine replacement needs. The lack of timely urine monitoring increases caregiver burden, risks moisture-related complications, and leads to resource waste from premature diaper changes. In this study, we designed and developed a conductive fiber-based sensor for diaper urine monitoring employing Radio Frequency Identification (RFID) technology with advantages of precise real-time urine monitoring, battery-free sensing, low production cost, and repeatable usage. An innovative embroidered net structure was first used for this tag antenna with optimized dimensions of T-match structure to achieve high sensitivity and stable signal strength attenuation behavior in relation to urine volume. An embroidered dual-tag sensor was designed to eliminate the effect of motion-induced variations on signal transmission, which can accurately monitor urine content within a 3 m range. Moreover, a prediction model was constructed in this work, with 97.5% and 94.6% prediction accuracy for read distance and urine volume, respectively. The designed sensor resolved conventional diapers’ inability to quantify urine output, enhancing nursing efficiency and intelligent care capabilities.