Patent ID: 8114673

Claim:
An indicator for detecting an oxidising agent comprising: at least one redox sensitive material which displays different visible properties in the oxidized and reduced forms; at least one electron donor wherein the at least one electron donor is a mild reducing agent, and wherein the at least one electron donor is incapable of directly reducing the redox material; and at least one semiconductor material specifically sensitive to light of about 200-400 nm, the semiconductor material being selected from the group consisting of oxides of titanium, tin, tungsten, zinc, and mixtures thereof, wherein the redox sensitive material, electron donor, and semi-conductor material are in intimate contact with each other, and wherein upon irradiation of said semiconductor material by light of about 200-400 nm an electron is donated by the electron donor to the semiconductor material which in turn provides an electron to the redox sensitive material causing the redox sensitive material to become reduced, and wherein upon exposure to an oxidizing agent, the indicator irreversibly changes color.