Conventional UV sensors are mainly based on complicated mechanisms (e.g. optical waveguide and photoconductivity) which require difficult preparation procedures and additional equipments. However, as for areas like remote regions where no instrumented support is available, instrument-free methods are highly desirable. Therefore, it is necessary to design portable devices with simple operation and no additional devices but with similarly good performance as such well-established sensors mentioned above. In this contribution, we will introduce a novel paper-based photochromic UV sensor by simple dip coating and benzophenone crosslinking strategies. Thus, photochromic spiropyran containing polymer networks were covalently formed on the paper substrate. With the adjustment of polymer concentration in the coating process, the different attached polymer mass could be realized. When it is exposed to UV light, the functional paper turns purple and the color intensity increases with the increment of UV dose until a stable value is reached. Based on the study of switching kinetics in the system, we can easily determine the UV intensity by analysis of the color change. With damping method, the sensitivity of the sensor can be simply controlled. In addition, visible light can fade the UV-illuminated purple paper to its original color, indicating the reusability of our paper-based UV sensor. With an easy fabrication and operation method as well as a high and adjustable sensitivity, our light-weight novel UV sensor show a promising prospect in remote areas or lab work.

Low instrumented colorimetric paper-based photochromic UV sensor

251st National Meeting (2016)

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