The Development Of The Thermal-film Air-mass Flow Sensor

Flow sensor is one of the three most widely applied sensor.With its development sensor based heater applied to physics, chemistry, biology arc paid much more attention, and it becomes one focus in the field of sensor.Thermal film air-mass sensor is one of this kind.This thesis expatiates on the basic theory of Thermal film air-mass sensor and sensor's structure and characteristic introduced detailly.Illustrales one kind of structures of the thermal air-mass sensors to introduces the relation between the change rate of the thermal sensitive resistance caused by velocity of flow and output voltagc,when this sensor working in constant current ,goes with its explaned in terms of mathematic mode.This task adopt MEMS technics to make Thermal -film air-mass sensor,mostly work is the study and facture of the sense organ of the chip. Theory illustrates and validates in detail from the following aspects: choosing of sensitive resistanc, designing the structure of the sensitive resistance, processing facture and signal process circuit. Finally, give out the linear relationship of mass flux and output voltage when working in constant temperature.The purpose of studying thermal-film air-mass sensor is to master MEMS technics , make membrane thermal sensitive resistance, grip the ralation of sensitive resistance, mass fiux and output voltage, expect geting well capabilities replace imports so as to advance application of this kind sensor.