Artificial Intelligence-Enabled 4-Dimensional Printed Hydrogel Wearables: Temperature and Ultraviolet Monitoring

Integrating smart wearable technology into daily life is becoming increasingly important for monitoring environmental factors such as temperature and ultraviolet (UV) radiation, both of which can impact health. Prolonged UV exposure is linked to skin cancer and eye damage, while major temperature changes can affect comfort and well-being. This study focuses on the manufacturing process of a novel smart wearable made from a hydrogel composite to monitor these environmental changes. The composite, consisting of hydroxyethyl methacrylate (HEMA) and polyethylene glycol diacrylate (PEGDA) with triphenylphosphine oxide (TPO) as the photoinitiator, is manufactured using digital light processing (DLP) 3-dimensional (3D)-printing. The HEMA to PEGDA ratio was optimized to achieve plastic-like durability. Tensile tests showed that both the hydrogel composite and nylon samples exhibited almost identical stress-strain behavior, with a tensile strength of approximately 40 MPa. Thermochromic and photochromic powders were added to provide dynamic color responses to temperature and UV light. The thermal color transitions are linked to an artificial intelligence model specifically trained to decode these hues into temperature measurements. Additionally, the photochromic aspect of the wearables acts as a visual alarm against UV exposure and thus advises on the potential requirements of protective measures.