Fully Printed Flexible Zinc Oxide Patch for Wearable UV Light Sensing

Metal oxide materials are widely adopted in UV sensing due to their advantages of reliability, stability, and high sensitivity. However, the fabrication of metal oxide films on flexible substrates using micro/nano printing techniques still poses challenges. Notably, inks containing oxide nanoparticles often lead to nozzle clogging during the printing process. In addition, methods relying on precursor solutions typically require high post-processing temperatures that conventional flexible substrates cannot withstand. In this study, a novel precursor ink based on zinc amine hydroxide complexes is proposed, enabling post-processing at a low temperature of 250 °C. Through a fully printed approach, a wearable UV sensor based on a zinc oxide nanofilm on a flexible substrate is successfully fabricated. The sensor exhibits outstanding sensitivity and rapid response characteristics. By incorporating silver nanoparticles into the ink, the baseline resistance of the sensitive material is adjusted. Furthermore, a smart patch utilizing the NFC communication protocol is developed, allowing for wireless, passive, and wearable UV detection. In this study, a process paradigm for fabricating metal oxide films on flexible substrates using micro/nano printing techniques is introduced, showcasing significant potential in the field of micro/nano sensor fabrication.