Paper-Based Flexible UV Radiation Monitoring Devices with an IGZO Sensing Layer for Wearable Electronics

Ultraviolet (UV) radiation is considered to be the predominant contributor to skin cancers in humans and requires the development of innovative, low-cost, and sustainable devices with real-time radiation monitoring capabilities to address this issue. This work presents the demonstration of low-cost UV radiation sensors with indium gallium zinc oxide (IGZO) as a sensing layer, fabricated on paper substrates to instill decomposability, which has been one of the crucial requirements for sustainable electronics. These sensors exhibit excellent responsivity (R) of 25 mA/W and detectivity (D) of 1.6 × 1012 Jones for 365 nm UV light with a 300 μW/cm2 input illumination power, in addition to good flexibility demonstrated by almost unvarying performance during horizontal, vertical, and diagonal bending conditions. High performance of these sensors enables them to be used for integration with commercial electronics, facilitating real-time wireless UV monitoring. Real-time monitoring with wireless transmission of data to smartphones was successfully demonstrated with these devices pasted on skin and wearable apparel, such as caps. Finally, the decomposability of these devices was demonstrated in highly moist soil in 15 days, indicating suitability for sustainable electronics. This work can enable the development of eco-friendly wearable devices for UV exposure monitoring.