Patent ID: 7228735
Filing Date: 2007-06-12
Classification: G01F,G01N

Abstract:
1. A fluid sensing device comprising: a micromachined tube comprising a base, a fluid inlet and a fluid outlet in the base, a freestanding portion extending from the base, and a continuous passage within the freestanding portion, the continuous passage being fluidically connected to the fluid inlet and the fluid outlet so as to accommodate a fluid flowing through the micromachined tube; means for vibrating the freestanding portion of the micromachined tube at a resonant frequency thereof; means for sensing movement of the freestanding portion of the micromachined tube; a substrate having a surface to which the base of the micromachined tube is attached, the base of the micromachined tube being spaced apart from the surface of the substrate so as to define a gap therebetween in a direction normal to the surface of the substrate, the freestanding portion of the micromachined tube being suspended over the substrate so as to be spaced apart therefrom, the substrate having first and second passages having openings at the surface of the substrate, the first and second passages being fluidically connected to the fluid inlet and fluid outlet, respectively, of the micromachined tube, whereby the first and second passages of the substrate are fluidically coupled through the continuous passage of the micromachined tube; a bypass passage defined by and between the base of the micromachined tube and the surface of the substrate, the first and second passages of the substrate being fluidically coupled through the bypass passage and thereby enabling a first portion of a fluid flowing from the first passage of the substrate to the second passage of the substrate to flow through the bypass passage while a second portion of the fluid flows through the continuous passage of the micromachined tube; and a fluid-tight sealing material within the gap between the base of the micromachined tube and the surface of the substrate, the sealing material surrounding the openings of the first and second passages of the substrate and the fluid inlet and outlet of the micromachined tube and defining a boundary of the bypass passage in a plane parallel to the surface of the substrate.