Online fluid-monitoring using an electromechanical cantilever

The parameters viscosity and density of a fluid or liquid may give information on its condition and consistence. In many industrial applications this information is essential and should be available throughout the whole process. Conventional viscometers and hydrometers are mostly bulky and slow in response time. Microacoustic liquid sensors based on the piezoelectric effect could overcome these problems. For Newtonian liquids a variety of devices using the transversal shear effect or surface acoustic waves is already in the market. They are operated at very high frequencies and relatively small amplitudes of vibration resulting in a small decay length into the contacting viscous fluid. For non-Newtonian liquids or emulsions an electromechanical cantilever resonating at lower frequencies with much higher deflections may be better suited. In this work, a trimorph-type cantilever is investigated by measurements and finite-element simulations. It is shown that the cantilever could be feasible for the online monitoring of fluids or liquids.