Direct insertion detection involves inserting a zirconia probe directly into the high-temperature gas being measured to real-time measure the oxygen content of the gas. This method is suitable for gas environments ranging from 700 to 1150°C (special structures can extend to 1400°C), utilizing the gas's own heat to reach the working temperature of the zirconia, without the need for an additional heater. The technical challenge lies in the high-temperature sealing of ceramic materials and the electrode design.