A Viscosity Sensor Using AT-Cut Quartz Resonator

A quartz resonator can be modified as a series circuit consisting of an inductance (L-1), a capacitance (C-1), a resistance (R-1) in parallel with a capacitor (C-0). With contacting fluid, the quartz resonator will generate a compression wave in the fluid and cause acoustic energy to radiate away. This effect will result in both a decreases in the resonant frequency of the resonator and an increases in the damping of the resonance; an extra inductance (L-2) and a resistance (R-2) series section will appear in the equivalent circuit. Beside the initial properties of the quartz resonator, the L-2 and R-2 are related to the density and viscosity of the contacting fluid. So the density and viscosity can be measured and calculated by L-2 and R-2. The purpose of this paper is used the property that the fluid loading will cause the shift of resonant frequency and using equivalent circuit method to calculate the viscosity of different sucrose-water mixture.