Advanced Sensing Strategies for Rare Earth Elements: Materials, Mechanisms, and Emerging Technologies

Rare earth elements (REEs) are essential to the production of clean‐energy systems, advanced electronics, biomedical equipment, and other high‐technology applications. The technological significance, nevertheless, repeatable detection and monitoring of REE is difficult because they have high chemical similarity, low concentrations in the natural environment, and because of the complexity of real sample matrices. This review is a concise summary of REE sensing, how their basic chemical properties and behavior in the environment are related to the contemporary analysis problems in environmental, industrial, and biological systems. In an effort to overcome traditional drawbacks, new developments in optical, electrochemical, colorimetric, SERS‐based, and hybrid sensing are critically discussed, especially in nanomaterials, functionalized polymers, and metal‐organic frameworks. New tendencies in portable and miniaturized devices, integration with IoT and artificial intelligence, and the creation of sustainable and green strategies of sensing in accordance with the principles of a circular economy are also mentioned. More importantly, many sensors reported have very low detection limits under ideal laboratory conditions, but their readiness for analysis in real environmental, industrial, or biological applications is subject to validation in real matrices, such as matrix spike recovery studies, selectivity, precision, and comparison with reference methods.