Droplet as a Mechanical Coupling for a Vibrational System and its Application in Fluid Property Sensing

This paper reports a coupled oscillator structure as a viscosity-density sensor. A liquid droplet serves as a mechanical coupling between the two mechanical plates. One plate is actuated. The other plate is passive and vibrates due to energy transferred through the droplet. The frequency response of the plates is measured for different glycerol water mixtures (GWM). Actuated plate velocity is shown to vary linearly, with the density ranging from 996 kg/m
³
to 1214 kg/m
³
. The Q-factor of the passive plate’s first mode decreases with viscosity. Using a small volume of fluid provides a higher Q-factor enabling functionality over a larger viscosity range of 0.89mPa.s to 67mPa.s.