Design And Fabrication Of Biomimetic Hair Vector Flow MEMS Sensor

Accurately measuring the velocity distribution of the aircraft’s flow field is of great significance for analyzing the aerodynamic performance and achieving the active flow control of the aircraft.With the rapid development of small aircrafts,it is an urgent need for a micro-sensor that can distinguish air velocity changes in 0.01 m/s,has a wide range of 100 m/s,high resolution,small size,low power consumption,and is easy to integrate,so as to meet the aerodynamic testing needs.At present,there are no sensors available in the market that can meet the above requirements and have low interference to the flow field.Recently,bionic microsensors based on bionics and MEMS(MicroElectro-Mechanical System)technology have showed excellent performance.Therefore,a bionic ciliated vector flow velocity microsensor is proposed and designed based on MEMS technology in this paper.The specific research work is as follows.First,the overall structure of the bionic ciliated vector flow velocity microsensor was designed.The main structure of the sensor includes four groups,which are curved folded beams,suspended films,multi-ciliated columns,and asymmetric comb electrode pairs.Secondly,a fluid-solid-static simulation analysis was performed on the bionic ciliated microsensor using a combination of analytical method and finite element numerical calculation.Subsequently,the basic law of flow velocity-cilia motion-detection capacitance was obtained,and the sensing mechanism analysis of the bionic ciliated vector flow velocity microsensor was completed.The analysis results show that the air flow velocity measurement range of the designed sensor reaches 100 m/s,the sensitivity is 1.45 f F/(m/s),and the resolution is better than 0.01 m/s.Then,the complete fabrication process flow of the microsensor was designed,and a complete set of photolithographic masks were made.Afterwards,a micro-machining process was used to fabricate a bionic ciliated MEMS vector flow velocity sensor.The main process steps used are:photolithography,sputtering,ion beam etching,deep silicon reactive ion etching,wet etching,supercritical release,etc.Finally,a preliminary electrical signal test,specifically the sensor differential capacitance measurement,was performed on the completed bionic ciliated vector flow velocity microsensor.The measured initial differential capacitance of the processed microsensor was about 1 p F.The test results show that the initial position offset of the microsensor comb electrode pair is about 0.8 microns.If the capacitance detection chip AD7746 is applied,the range and resolution demand of the microsensor can be achieved.Therefore,preliminary processing experiments and capacitance test experiments verify the sensor’s feasibility.