Fully integrated micro coriolis mass flow sensor operating at atmospheric pressure

This paper discusses the design and realization of a micromachined micro Coriolis flow sensor with integrated electrodes for both electrostatic actuation and capacitive readout. The sensor was realized using semicircular channels just beneath the surface of the silicon wafer. The channels have thin silicon nitride walls to minimize the channel mass with respect to the mass of the moving fluid. A comb-shaped electrode design is used to prevent squeezed film damping so that the sensor can operate at atmospheric pressure, thus eliminating the need for vacuum packaging. The new sensor chip no longer requires large external magnets and the size of the chip itself has been reduced to 7.5 x 7.5 mm2.