Miniature density-viscosity measurement cell utilizing electrodynamic-acoustic resonator sensors

Miniaturized physical sensors for precise density and viscosity measurement are required as supplement or replacement for complex and expensive laboratory instruments. Utilizing miniature mechanical resonators as transducers, one can greatly reduce the necessary liquid volume, measurement time, and complexity of the experimental setup. In this contribution, we describe the development of a miniature, modular measurement setup for a large viscosity range. We devised and fabricated an inexpensive flow-through cell using milling technology of multiple PCB layers and Parafilm or Teflon sealing for easy assembly and disassembly. The mechanical resonator is designed as a suspended plate using electrodynamic Lorentz force excitation and movement induction detection. Quality factor and frequency shift of the resonator are evaluated and related to the density-viscosity product of different test liquids at multiple resonant modes of vibration at low operating frequencies for different temperatures and over a wide range of different viscosities.