Responsivity evaluation of fluorescent thin films for sensitizing a CMOS sensor in the UV range for cellular proliferation imaging

Cellular proliferation in lesions may be assessed by imaging the intrinsic fluorescence of the tryptophan amino acid at 345 nm, which may be modified by chronic diseases. Typical image sensors have a limited responsivity, particularly at the UV interval. A fluorescent coating with an absorption peak at the emission wavelength of interest and an emission peak near to the sensor maximum sensitivity may improve the sensor responsivity. In this work, considering our final aim of imaging the intrinsic emission associated to the in-vivo cellular proliferation, fluorescent-thin films of two types of europium-activated phosphors at different concentrations were deposited by the spin-coating technique in a glass substrate and evaluated. The PTG505/F and UKL63/F-U1 phosphors were used for the coatings, these were excited at 345nm, and the quantum efficiency at 515 and 625 nm were assessed, respectively. The results showed that the PTG505/F and UKL63/F-U1 coatings may provide films with a thickness of less than 10 μm, and QE 130% to sensitize image sensors.