Development of Micromachined Thermal Flow Sensor with Thermopiles

Abstract

This paper describes an ultra compact and high sensitivity fluidic sensor suitable for measuring flow velocity and direction with the operating principle of detecting flow-induced temperature gradient on the surface. This flow sensor is fabricated utilizing surface micromachining technologies on a silicon substrate. The flow sensor has high sensitivity of flow velocities as high as 0.01m/s. Polycrystalline silicon (poly-Si) film heater and poly-Si/Aluminum thermocouples are adopted on a dielectric thin film membrane thermally isolated from the substrate.