No abstract

This paper introduces a fluorometer that is both economically viable and optimized for sensitivity. The sensor is designed to detect low concentrations of fluorophores in the visible spectrum range, utilizing a deep ultraviolet (DUV) 275-nm LED and a dichroic mirror to establish a co-axial optical path for excitation and emission. Unlike traditional general-purpose spectrometers, this sensor achieves a balance between the two through an appropriate aperture size and tailored optical design optimized for the spectral characteristics of fluorophores. The manuscript presents measurements of rare earth element (REE) samples containing terbium (Tb), europium (Eu), dysprosium (Dy), and samarium (Sm) in aqueous solutions at ppb-level concentrations. By optimizing the collection of fluorescence emission without sacrificing spectral information, this work demonstrates the feasibility of developing a low-cost, compact, and highly sensitive fluorescence sensor that is comparable to bench-top commercial spectrofluorometers at a fraction of the cost.