热式MEMS流量传感器的设计及测试

摘要

根据已有的热式MEMS气体微流量传感器芯片的各部分热敏电阻热串扰现象严重,造成很大的测量误差,改进设计了一种MEMS热式流量传感器,将加热电阻和上下游测温电阻采用悬臂梁隔离结构,并相互隔离,有效的避免了热膜流量传感器各部分热敏电阻间相互热串扰现象.基于改进的MEMS热式流量传感器,设计了流量传感器的测试系统,包括恒温差电路、桥式测量电路及放大、滤波电路,所采集的流量信号经过滤波放大后输入AD模块进行模数转换,最后经过单片机处理,利用单片机与计算机串口通信功能,在不同流速下打印出不同的电压值;通过Matlab对所测出的数据进行拟合,完成对传感器性能的检测.测量结果表明:在一定的流量范围内,该流量传感器具有测量精度高、响应速率快、输出信号平滑等特点,能够广泛应用于工业、医疗领域的流量测量.%The thermal resistance thermal crosstalk of various parts for original thermal MEMS gas micro-flow sensor chip has been serious,which causes a large measurement error.A kind of MEMS thermal flow sensor has been improved and designed.The heating resistor and the upstream & downstream temperature measurement resistors have been separated by the cantilever beam and isolated from each other,which effectively avoids the thermal crosstalk between the thermal resistors of the hot film flow sensor.On basis of the improved MEMS thermal flow sensor,the testing system of the flow sensor has been designed,including the constant temperature difference circuit,bridge measurement circuit & amplification,and filter circuit.The collected flow has been input into the AD module for analog-digital conversion after being filtered and amplified.Finally,through the single-chip processing,by use of communication function between single-chip and computer serial,the different voltage values have been printed at different flow rates.The fitting has been conducted to the measured data by Matlab to complete the detection of the sensor performance.The measurement results show that the flow sensor has the characteristics of high measurement precision,fast response rate and smooth output signal in a certain flow range,which can be widely used in industrial and medical field measurement.