A novel two dimensional particle velocity sensor

In this paper we present a two wire, two-dimensional particle velocity sensor. The miniature sensor of size 1.0x2.5x0.525 mm, consisting of only two crossed wires, shows excellent directional sensitivity in both directions, thus requiring no directivity calibration, and is relatively easy to fabricate. The sensor consists of two crossed beams of SiRN with a platinum layer on top. These beams are used both as heaters and sensors. Two currents with equal amplitude are injected in both terminals of one of the beams and are extracted from the terminals of the other beam. A particle velocity component in the direction of a beam will cause it?s temperature, and thus resistance, profile to change asymmetrically. This asymmetry in resistance will give rise to a voltage difference across that beam which is proportional to the particle velocity level. The sensor shows a frequency bandwidth between 20Hz en 10kHz. The two figures of eight are exactly perpendicular to each other as desired, which was difficult to obtain in earlier implementations using parallel beams. Furthermore, the structure consisting of two crossed wires increases the mechanical robustness of the beams resulting in fabrication yields of 94% as opposed to 70% in earlier implementations.