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 films. In this study, MEMS techniques are used to deposit a platinum layer on the substrate to form resistors which is to regard as heater and sensing elements. As air flows through the heater and 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 variations as airflow velocity changes from 0 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 due to its faster response and higher sensitivity.