Carbon Monoxide detectors are the powerful SOS alarms that recognize and alert on the presence of harmful gas. The sensors are of four types mainly: first is the biomimetic sensor that has a liquid or a gel to detect CO, the types of detectors last up to three years. The second type is the Metal Oxide Semiconductor, which is made of wired circuits, and it lasts up to 10 years. The electrochemical sensor, the third and the best carbon monoxide detector and has electrochemical detectors and is long-lasting. The fourth type has a pad that changes color when carbon monoxide is found and is called the Optochemical sensor.