Polymeric film-based colorimetric chemosensors for ion detection

• The use of colorimetric chemosensors for ion detection is outlined. • Polymeric films represent robust matrices for chemosensor development. • Polymeric film-based colorimetric chemosensors offer sensitivity, selectivity, and ease of use. • The analytical performance of the chemosensors has been evaluated and compared across different techniques. • Strategies for practical application and future commercialization of these devices have been presented. In the past decade, polymeric film-based colorimetric chemosensors have emerged as a promising technology for ion detection. This review examines the literature on these chemosensors, providing an overview of their preparation methods, their properties, tools for quantifying colorimetric signals (including naked-eye detection and colorimetry using colorimeters, digital image processing, or UV–Vis spectroscopy), and their analytical performance. Most of the evaluated works focused on the determination of metal ions, highlighting the need for research targeting other types of ions. Although UV–Vis spectroscopy was employed in almost 50% of the studies, digital image colorimetry is emerging as a simpler and more cost-effective alternative for quantifying colorimetric signals of the chemosensors. The analysis of the published works enabled the identification of key advances, existing gaps, and potential future directions for enhancing the performance of these chemosensors and broadening their range of applications, particularly in the detection of environmentally and industrially relevant analytes.