Visible light activated ion sensing using a photoacid polymer for calcium detection.

Presented here is a sensing membrane consisting of a modified merocyanine photoacid polymer and a calcium ionophore in plasticized poly(vinyl chloride). This membrane is shown to actively exchange protons with calcium ions when switched ON after illumination at 470 nm, and the exchange can be followed by UV-vis spectroscopy. The sensing membrane shows no response in the ON state when calcium ions are absent.