Patent ID: 8408073

Claim:
A method of determining at least one property of a gas-containing fluid comprising at least a first gas in at least a first fluid, the method comprising: providing a freestanding tube portion supported above a surface of a substrate so as to be capable of vibrating in a plane normal to the surface of the substrate, the freestanding tube portion having a continuous internal passage, a fluid inlet portion of the internal passage through which the gas-containing fluid enters the freestanding tube portion, and a fluid outlet portion of the internal passage through which the gas-containing fluid exits the freestanding tube portion; flowing the gas-containing fluid through the internal passage of the freestanding tube portion; generating a drive signal to vibrate the freestanding tube portion at a resonant frequency thereof and avoid alternative vibration modes of the freestanding tube portion, wherein the resonant frequency is proportional to the density of the gas-containing fluid, the Coriolis effect causes the freestanding tube portion to twist about an axis of symmetry thereof while being vibrated at the resonant frequency, and the freestanding tube portion exhibits a degree of twist that varies with the mass flow rate of the gas-containing fluid; sensing deflections of the freestanding tube portion relative to the substrate and producing an output corresponding to the sensed deflections; and assessing the drive signal and the output to determine at least the volume of the first gas in the gas-containing fluid.