Introduction
Recently, a wide range of wearable devices were reported that report on the personal UVA (400–320 nm) and UVB (315–280 nm) radiation dose in real-time. These devices employ UV-sensitive dyes that undergo a chemical reaction upon irradiation, which in turn generates a colored dye as indicator to provide a signal for readout. The most important is that these wearable devices can provide information about the UV-radiation threshold and monitor UV radiation to rationally manage the user's behavior in order to prevent harmful sun exposure.
Figure 1. UV-Sensitive wearable devices
Mechanism
Various UV-sensitive dyes have been reported. Here, take the triphenylsulfonium photosensitizer for example. Upon irradiation, the photosensitizer (triphenylsulfonium) triggers a hydride transfer from the triphenylmethyl dye (p-aminophenyl) methyl leucobase) so that the leucobase is transformed from its amino to its imino form and changes color. Figure 2 shows the process of color change for the example of triphenylsulfonium as photosensitive initiator and tris(4-(N,N-dimethylamino)phenyl) methane (Leuco Crystal Violet) as oxidizable indicator.[1] Further irradiation results in photodegradation as the chemical structure of these dyes is destructed. Through this controllable oxidation by selective irradiation with light of different intensities and duration, the color conversion can be precisely controlled and therefore provides accurate visual colorimetric data about the UV light exposure and duration.
Figure 2. Process of color change of leucobase upon irradiation-triggered decomposition of photosensitive initiator.
What Can Alfa Chemistry Do?
Alfa Chemistry's technical R&D team has focused on the preparation and application of UV-sensitive dyes for many years, which has established long-term cooperative relationships with many well-known enterprises and research institutions. We have conducted research on various problems encountered by UV-sensitive wearable devices, which can select the appropriate solution according to the customer's experimental purpose. The related technologies of UV-sensitive wearable devices we provide are as follows:
- We can provide UV intensity test and select the appropriate UV-sensitive dyes for customer.
- We can customize relevant solutions to meet customer needs in order to help researchers solve the problems.
Reference
- Kurz W.; et al. UV-Sensitive wearable devices for colorimetric monitoring of UV exposure. Adv. Optical Mater., 2020, 8(6): 1901969-1901978.
