A MEMS-based vortex flow sensor for aggressive media

We report for the first time a MEMS-based multi-function flow sensor for aggressive media based on the vortex shedding principle. The flow sensor operates by detecting the frequency of the periodic pressure variations that are induced when fluid in a pipe passes a bluff body. The sensor is a compact, low-cost combined flow and temperature sensor which is suitable for use in chemically harsh environments due to a corrosion-resistant coating allowing direct exposure of the piezo-resistive pressure sensor chip to aggressive media. It is demonstrated that the flow sensor enables accurate flow and temperature measurement over a wide dynamic range that also covers very low flow rates.