A New Capacitive MEMS Flow Sensor for Industrial Gas Transport Monitoring Applications

Abstract

This paper introduces a new MEMS micro cantilever chip for mass flow rate and flow velocity measurement in a harsh environment where combustible gas flows are the working fluid. In such a condition, using thermal flow sensors is hazardous and may threaten a staggering amount of investment and human lives by igniting the gas flow which might lead to an explosion. To overcome these drawback mechanical sensors are more desirables for such environments. Here we have designed a MEMS chip consist of 74 polysilicon micro cantilevers that are operating based on a capacitive detection mode. There are micro cantilevers with 50, 100, 250 and 400 µm in length and same thickness and wideness, 2µm and 50µm, respectively. This sensor is capable of measuring moderate flows up to 200 m/s in a 10 cm diameter pipes based on the current design for bypass. According to experimental results, the sensor output capacitance varied from 3.3445 pF to 3.350 pF for a range of flow between 0 to 30 m/s. We have shown that MEMS flow sensor can meet large size flow measurements in the industry.