Tokyo: Japanese scientists have developed a small, transparent film that can detect when fish and meat have begun to spoil, authorities reported on Tuesday. The plastic film is 1 cm long and reacts when placed on food products, and its use could help detect cases of food spoilage, according to a team of researchers, led by Professor Shizuo Tokito from the Yamagata University. The sensor works by detecting histamine, which accumulates when bacteria begins to decompose amino acids and even small amounts of which can cause symptoms of food poisoning, EFE news reported. The sensor was developed by printing an electrically conductive material on a plastic film, and in the future could integrate wireless circuitry into the sensor film so that food freshness can be monitored with devices like smartphones. Currently there are other similar sensors in the development phase but are of a much larger size, underlined the researchers, who seek to develop a commercially viable prototype in three years.