A carbon monoxide gas sensor is fabricated using a tin oxide semiconductor. The sensing element is heated periodically to maintain its high sensitivity to CO gas. An activated carbon filter is put over the element to give preferential detection of CO gas. By adopting double elements, the interval between detections is shortened by half. Signals from the sensing elements are processed by a Z-80 microprocessor, so that the CO sensor and the microprocessor, along with other sensors and components, form a detection system. This system has a high reliability and is effective for preventing disasters caused by CO poisoning and fire. © 1990.
