Smart Diaper with Printed Capacitive Sensors and Integrated Front-end to Monitor Voided Fluid Volume

As the demographic structure of the global population continues to shift towards an aging population, caregivers encounter formidable obstacles in detecting wetness events and assessing the quantity of voided volume within diapers. Nevertheless, the integration of electronics with diapers, frequent removal and reapplication, and battery management still pose practical challenges. In this study, a solution of carbon and silver printed flexible capacitive sensors interfaced with a custom-designed application-specific integrated circuit (ASIC) is proposed to detect urination events and estimate voided volumes in diapers. A power-optimized application-specific front-end interface circuit is developed to enhance power efficiency and reduce battery maintenance. The circuit is designed to support power-harvesting-based operations and to reduce reliance on external sources, consuming a maximum power of 3.05 μW. In vitro measurements validate on-chip electronics functionality and sensor performance to detect and quantify voided fluid volume as low as 50 ml. The promising results pave the way for cost-effective, disposable solutions in smart diapers. The proposed solution improves efficiency and comfort for both caregivers and elderly individuals.