Though human vision is limited to the visible region of the electromagnetic spectrum, giving humans the ability to easily detect ultraviolet (UV) wavelengths has many potential applications. These include devices to measure UV levels outside, security paper, and the development of chemical artificial intelligence. The distinction between the three regions of ultraviolet light was accomplished using a system of photochromic species, whose behavior can be rationalized using the theory of fuzzy logic. The bands of the compounds’ absorption spectra are the input fuzzy sets, whereas the absorption bands that appear in the visible region upon irradiation with ultraviolet light are the output fuzzy sets. Photo-coloration and bleaching experiments were performed for each individual compound, allowing for the determination of the kinetic bleaching constants and quantum yields in the UVA, UVB, and UVC regions. Various mixtures of the species were analyzed to find a combination with the largest differences in absorption spectra and color upon irradiation at the different UV regions. A reusable paper device infused with this solution effectively demonstrated the expected color changes. Reflectance measurements and calculation of the color coordinates confirmed the distinguishability of the UV regions on paper. Both the solution and paper device were tested with various light sources, including direct sunlight, light on a cloudy day, sunlight along with a low pressure mercury lamp, and scattered light with a low pressure mercury lamp.

Expanding human perception of electromagnetic radiation to the ultraviolet region through fuzzy logic photochromic systems

251st National Meeting (2016)

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