A Paper‐Based Wearable Photodetector for Simultaneous UV Intensity and Dosage Measurement

TLDR

Photodetectors convert light into signals and are widely used, but existing devices only report either transient intensity or absorbed dosage, not both simultaneously. This work presents a paper‑based wearable photodetector that can simultaneously measure transient light intensity and accumulated dosage. The device employs a phosphomolybdic acid/citric acid photochromic system combined with 2D Sr₂Nb₃O₁₀ and ZnO nanoparticle photodetectors printed on paper. It shows flexible, durable performance with stable optoelectronic signals over 1000 bending cycles and is the first photodetector to report both light intensity and dosage simultaneously.

Abstract

Abstract Photodetectors, which convert the light signal into other forms of signal, have been under the spotlight of research for many years because they are widely applied in monitoring, communication, and imaging. Most of the currently available photodetectors can output electrical signals to indicate the transient light intensity, while some display color change to reveal the absorbed light dosage. However, there is no device that can tell the transient light intensity and accumulated light dosage at the same time. Here, a paper‐based wearable photodetector that can simultaneously measure transient light intensity and accumulated light dosage is reported. The phosphomolybdic acid/citric acid system, whose color change can be observed by the naked eye, is designed as the photochromic material to combine with photodetective materials (using 2D Sr 2 Nb 3 O 10 and ZnO nanoparticle as examples) on paper. Such paper‐based photodetector fully utilizes natural hygroscopicity and softness of paper, showing decent flexibility. Its optoelectronic signal remains stable even after 1000 cycles of bending. To the best of one's knowledge, this is the first photodetector that can tell light intensity and dosage simultaneously. This work introduces a new type of wearable photodetector by structure design and material selection, shedding light on more novel works for convenient and practical photodetection.