Semiconductor gas sensor

Patent Granted Semiconductor sensors detect gases by a chemical reaction that takes place when the gas comes in contact with the sensor. Tin dioxide is the most common material used in semiconductor sensors,[8] and the electrical resistance in the sensor is decreased when it comes in contact with the monitored gas. The resistance of the tin dioxide is typically around 50 kΩ in air but can drop to around 3.5 kΩ in the presence of 1% methane.[9] This change in resistance is used to calculate the gas concentration. Semiconductor sensors are commonly used to detect hydrogen, oxygen, alcohol, and harmful gases such as carbon monoxide.