Micro Coriolis Mass Flow Sensor with Large Channel Diameter by Wet Etching of Silicon

In this paper, a new Coriolis mass flow and density sensor is presented. The fabrication process of the sensor is based on existing Surface Channel Technology (SCT) but uses selective wet etching to realize the channels, which results in suspended microfluidic channels with a relatively large cross- sectional area. Thanks to the large cross-sectional area of the channel, the flow range of the sensor is expanded from 1.2 g/h to more than 50 g/h (water) compared to the standard SCT based Coriolis sensor, while keeping the pressure drop lower than 1 bar. The fabricated channels have a semi-elliptical cross-sectional area with a width of 200 μm and a depth of 70 μm. The channel wall is made of a stack of thin films with a total thickness of $2.5\ \mu\mathrm{m}$. Water and isopropyl alcohol (IP A) were used for mass flow measurements to demonstrate that the Coriolis mass flow sensor is indeed sensitive to mass flow.