A Method to Compensate the Pressure Sensitivity of Integrated Thermal Flow Sensors

Microelectromechanical systems (MEMS)-based thermal flow sensors are considerably more sensitive to pressure than traditional macroscopic devices. This fact, due to the micrometric dimensions of MEMS sensors, limits the accuracy of the latter when large pressure variations cannot be avoided. In this work, we propose an original pressure compensation method that exploits the same signals produced by the flow sensor to detect the pressure variations and to control the heater power according to a closed loop approach. A first-order model is used to explain the operating principle and optimize the parameters of the feedback loop. A readout interface based on the proposed approach, has been built and applied to MEMS thermal flow sensors. Experimental results are presented to demonstrate the effectiveness of the method.