VORRICHTUNG ZUR ERKENNUNG VON SCHWEBSTOFFEN

A particulate matter (PM) sensor capable of stably detecting a particulate concentration regardless of the operating state of an engine and the temperature of exhaust gas is provided. The PM sensor has a sensor electrode unit provided in an exhaust gas path of the engine and detects the PM concentration in exhaust gas based on an electrical characteristic of the sensor electrode unit on which PM contained in exhaust gas deposits. The variation amount ”C of capacitance of the sensor electrode unit is measured in a state in which the temperature of PM deposited on the sensor electrode unit is controlled to within a stable PM temperature range in which the electrical property is stable, and the PM concentration in exhaust gas is detected in accordance with the variation amount ”C of capacitance thus measured.