Design and fabrication of a drag force type air flowmeter with polyoly -silicon piezoresistive iezoresistive iezoresistive layer

In this paper, we designed and investigated a drag force type air flowmeter with reduced temperature effect. For this purpose, poly-silicon was deposited as a piezoresistive layer. Adjusting the doping concentration, the temperature related factor like resistivity can be controlled. In addition, since the gauge factor is larger than other metals, the output signal was improved, and the temperature effect was also minimized. The structure was designed to enhance the air drag force. The two-cantilever structure and the paddle structure were utilized, and the device was perpendicularly placed to the given air flow. The flowmeter measured a wide range air flow rate from 0m/s up to 10m/s in the wind tunnel. The basic experiments for repeatability and the short-term stability were performed, and the stable outputs were obtained. The temperature effect was examined, and the output signal of the device showed a quadratic form according to the air flow, which signifies that the device has reduced temperature effect compared to other flowmeters with platinum piezoresistive layer.