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Color-Changing Nanopigment Sensor Tracks pH One to Ten with Stable, Repeatable Readings

South Korean chemists have engineered a nanopigment‑based colorimetric sensor that reliably measures pH across a full range from 1 to 10. By covalently attaching sulfonephthalein dyes to porous silica nanoparticles and embedding them in an agarose/PEO polymer, the sensor eliminates dye leaching and maintains linear color response over repeated cycles. The team demonstrated the technology by tracking shrimp spoilage, where the film’s color shifted from bright yellow to dark brown as pH rose. The authors suggest the platform could replace fragile electrochemical probes in many industrial and biomedical settings.