A Micromachined Gas Flow Sensor With Polydimethylsiloxane Flow Channels

In this paper, the design, fabrication, and response characteristics of the micromachined flow sensor were presented. The flow sensor comprising of two hot wires detects the flow rate by measuring the heat transfer of the two hot wires with mesh-membrane structure, which were supported by double-layer cantilevers and suspended in the flow channel. Polydimethylsiloxane instead of glass was used to fabricate the flow channels and seal the flow sensor at the room temperature, owing to its intrinsic structural economic, simplicity, and reliability. Moreover, the fabrication process of the flow sensor can avoid a high-temperature bonding process, resulting in higher sensitivity. The experimental results have indicated that the proposed flow sensor exhibited a linear response for flow rates up to 10 sccm, and the resolution of the flow sensor was less than 0.1 sccm. The four-cycle experiments suggested a reliability and repeatability of the proposed flow sensor.