Highly sensitive detection and imaging of ultraviolet-B light for precisely controlling vitamin D generation in the human body

Ultraviolet-B (UV-B, 290-320 nm) photons in the solar spectrum are essential for the generation of vitamin D, which plays an essential role in the absorption of calcium in the human body. However, excess UV-B irradiation can also induce diseases, such as erythema or skin cancer. Thus, the quantitative detection of UV-B is indispensable maximizing the advantages of this wavelength range. In general, due to scattering in the atmosphere, the UV-B signal that reaches the earth's surface is always too weak to detect. Here, we report a photodetector based on solution-processed ZnGa2O4 truncated octahedral microparticles, which exhibit a sensitive response to UV-B photons in the air, while not responding to UV-A or visible photons. An outstanding performance in accurate detection of a weak UV-B photon signal of 31.8 nW cm(-2) with detectivity of >4 x 10(14) Jones is achieved. To our knowledge, this is the first demonstration for the accurate detection of UV-B radiation at such low intensity. Other figures of merit in our photodetector, including high I-on/I-off ratio of >10(4) and low noise current of approximate to 2 x 10(-14) A Hz(-1/2), confirm the promising application of our detector in quantitative detection of UV-B photons in ambient or applied conditions for biological or medical applications.