Thermal Anemometer Using a Micro-Air-Bridge Heater with Chip Scale Wind Tunnel

Abstract

We developed a thermal anemometer using a novel sensor chip fabricated by the silicon micromachining technique. A chip scale wind tunnel on the sensor chip allowed the fluid to flow from the front to back side. Since conventional sensors using a micro-air-bridge heater were placed parallel to air flow, the heat transfer from the heater was influenced by turbulence generated from a chip edge or other micro structures. We expected that the chip scale wind tunnel bound air flow to keep regularity of heat transfer. By using the sensor chip, we produced a prototype thermal anemometer, and measured characteristics. The anemometer could measure wind velocity in the range of 0∼35m/sec. The directivity to wind direction was very symmetric at 5, 10, 15 and 20m/sec.