Fabrication and characterization of MEMS-based flow sensors based on hot films

The purpose of this paper is to propose two types of airflow velocity measurement modules, double-chip and single-chip, of MEMS-based flow sensors that consisting of heating resistors and sensing resistors on alumina substrates. In this study, MEMS techniques are used to deposit platinum films on the substrate to form resistors which are to regard as heaters and sensing elements. As air flows through the heater and the sensor, the temperature of the sensing resistor on the hot film decreases and the changes of the local temperature determine the airflow rate. The experimental results show the resistance linearly varies as airflow velocity changes from 5 to 28 ms⁻¹. Finally the experimental data indicate that sensing performance of the single-chip type is better than that of the double-chip type with its higher sensitivity (0.7479 Ω/ms⁻¹) due to the more rapid heat conduction from the heating resistor to the sensing resistor.