A molecularly imprinted polymer sensor device for detecting a specific inorganic target ion is disclosed. The device includes at least one or more molecularly imprinted polymer beads comprising a macroporous structure having a plurality of complexing cavities therein, wherein the complexing cavities contain cationic ligands spatially oriented to selectively receive and bind a specific inorganic target ion to be detected and having operatively associated therewith a light source for generating excitation energy of the beads.