Research And Fabrication Of Thermal Mass Flow Sensor Based On MEMS

As a key device for monitoring and measuring flow,flow sensor plays a vital role in industrial production,aerospace,automotive electronics,medical health and other fields.According to measurement principles,the flow sensor can be divided into thermal flow sensor and non-thermal flow sensor.The thermal flow sensor has been widely concerned by researchers because of its simple structure,high measurement sensitivity and low power consumption.With the continuous maturity of MEMS process,micro-nano machining chip based on MEMS process have been gradually applied to various fields because of their advantages of small size,low power consumption and high precision.In this paper,based on MEMS process,a thermal mass flow sensor is designed,fabricated,and its characteristics are tested and analyzed.In this paper,the thermal mass flow sensor based on thermopile structure is taken as the research object,and the problems encountered in the simulation,design,fabricating,packaging and other steps of the thermal mass flow sensor based on MEMS process are studied and analyzed in detail.Firstly,the theoretical knowledge of thermology,fluid mechanics and the structure and material selection of thermopile are analyzed and summarized.In order to understand the influence of each parameter on the sensor performance,the finite element simulation of the thermal mass flow sensor based on thermopile structure is carried out,including electric field,thermal field and fluid field.According to the simulation results,the MEMS technology was used to fabricate the sensor chip,and the chip structure was packaged with the flow channel,circuit and other structures,and the experimental platform was built to test the performance of the sensor.The test results show that the MEMS thermopile mass flow sensor designed in this paper has the advantages of low power consumption(13.56mW),high normalized sensitivity(4.905mV/sccm/mW),small size(1mm×3mm).It can be applied to aerospace,automotive electronics,medical health and other environments that require high performance of the flow sensor.