Special Polymer/Carbon Composite Films for Detecting SO₂

A family of polymer/ carbon films has been developed for use as sensory films in electronic noses for detecting SO2 gas at concentrations as low as 1 part per million (ppm). Most previously reported SO2 sensors cannot detect SO2 at concentrations below tens of ppm; only a few can detect SO2 at 1 ppm. Most of the sensory materials used in those sensors (especially inorganic ones that include solid oxide electrolytes, metal oxides, and cadmium sulfide) must be used under relatively harsh conditions that include operation and regeneration at temperatures >100 °C. In contrast, the present films can be used to detect 1 ppm of SO2 at typical operating temperatures between 28 and 32 °C and can be regenerated at temperatures between 36 and 40 °C.