An Environmentally Friendly Carbon-Printed Contactless Smart Diaper

Nowadays, with the aging population, the number of people in homes for the elderly is dramatically rising. Nearly, all of them suffer from a degree of incontinence and wear diapers on a daily basis, leading to a lot of superabsorbent polymer waste material. Smart diapers increase patient comfort owing to timely diaper changes. At the same time, the absorbent content of smart diapers can be reduced substantially, compared with regular diapers, as less margin for late changes is needed. From the medical perspective, smart diapers also reduce painful incontinence-associated dermatitis (IAD) caused by prolonged exposure to saturated diapers. This article proposes a novel contactless smart diaper system that allows caregivers to remotely read out information about diaper contents. The developed system is based on capacitive coupling to a printed structure in the diaper, including multiple detection zones distributed across its length. By printing the sensing pattern into the diaper in carbon ink, a low-cost, mass producible, and environmentally friendly sensor is obtained. A four-port differential transmission-measurement technique is employed, resulting in a higher system reliability than many existing smart diaper systems relying on impedance measurements only. This article includes both laboratory and in-field measurements to demonstrate the successful detection of moisture.