The Design And Study Of The Thermal-film Air Flow Sensor

The operation principle, geometry design, fabrication processes and measurement are investigated. Some method for the sensor working is discussed in the principle introduction, and the constant temperature working mode is recommended.The heating resistance and sensing resistance is designed separated structure which is different from traditional single resistance structure. The micro heater and temperature sensing based on the silicon is fabricated with the microelectronic technique and micro mechanical process. The thermally isolated btidge structure is able to reduce the thermal capacity and diathermancy, so that the high sensitivity is able to retain .The basic theory of Thermal-film air-mass sensor, sensor's structure and characteristic are introduced systemically. MEMS technology is adopted to make Thermal-film air-mass sensor, and the primary job in the thesis is focus on the sensitive chip study. Theory analysis and experiment verification are carried out on the following aspects:sensitive resistance material choice, structure of the sensitive resistance design and manufacture, signal process circuit design. The relationship between thermal temperature field and velocity of air flow is optimized by FEA.Finally, the performance and environment test have been done to the transducer. The results indicate that the performance of the sensor is excellent and reaches the desired design.In conclusion, combined with excellent performance, the sensor is even good at high sensitivity, small size, easy to be integrated. The transducer has already been used in the aviation, spaceflight field to control the air mass flow, and meets the military industry need.