There are two commonly used carbon monoxide sensors: electrochemical sensors and semiconductor sensors. The electrochemical sensor has high precision and good stability, so the price is relatively high. The power consumption of electrochemical sensors is low, and the alarms made can be powered by batteries. Semiconductor sensors consume high power and are usually not powered by batteries.

The semiconductor carbon monoxide alarm uses a semiconductor carbon monoxide sensor as a sensitive element, and it is required that the sensitive element can respond quickly when the temperature is about 200 °C, so it is necessary to add heating wire heating, so it needs to provide a relatively large current. Large changes are not good for its accurate measurement, and it is easy to be cross-interferenced by other gases, such as alcohol, nitrogen oxides, hydrogen, alkanes and other gases, which are prone to false alarms, but they are cheap. The general service life is up to five years.

Mini Smoke alarm(with 10 Y battery) LM-109C