Monthly Meeting

Projected rise in demand for economically critical minerals coupled with a monopolistic global marketplace for these minerals has caused concern over supply chain vulnerabilities, which would impact energy, national defense, and advanced technology manufacturing. Domestic production of critical minerals is hindered by expensive and non-portable methods for analyzing metal concentration, which is vital both for resource prospecting and process monitoring. Here, photoluminescence-based sensing materials and platforms will be discussed for multiple energy relevant metals, a suite of technologies that was recently selected as a 2025 R&D100 Awardee. Specific sensing materials include a metal-organic framework comprised of zinc, adenine, and trimesic acid capable of simultaneously detecting and distinguishing down to part-per-billion levels of the rare earths terbium, europium, samarium, dysprosium, ytterbium, and neodymium through a photosensitization mechanism. Moreover, immobilization of the sensing material onto an optical fiber platform enhances performance in harsh streams by enabling solvent removal, which reduces vibrational quenching, and also facilitates material recycling and re-use. The sensing material-coated tip is then integrated with a compact fiber optic platform for easy transport to the field. A similar optical set-up is coupled with two different carbon dot materials, which can detect low part-per-million concentrations of cobalt and iron in acidic environments and metal process streams. Additionally, monitoring of trace aluminum concentration is demonstrated using metal-organic framework thin films grown onto metal oxide substrates, and the sensor is successfully used to compare aluminum content in real fly ash leachates.