Anemometer for detection of very low speed air flow with three-dimensional directionality

This paper shows measurement of very low speed air flow with a new sensor. This micro-machined sensor contains two monolithically integrated orthogonal cells making it prospective to realize three-dimensional (3D) detection of the direction and velocity of air flow at one point. Each cell (vent) has a five-wire configuration, formed by five resistive beams of platinum (with pitch of 354 μm), sensitive to two direction. It was measured from 16.7 mm/s to 167 mm/s, showing good repeatability and demonstrating its directionality. Velocity distribution was simulated, and results corresponded to the theoretical lower limit of velocity of 50 mm/s due to natural convection, the induced angle dependent offset voltage of which can be taken into account to make a more accurate computation of lower velocity.