Precision density and volume contraction measurements of ethanol–water binary mixtures using suspended microchannel resonators

This article reports the thermomechanical characteristics of a suspended microchannel resonator (SMR) that can be exploited to measure the temperature-dependent density and volume contraction of ethanol–water binary mixtures. We found that the resonance frequency of an SMR exhibits non-monotonic temperature dependence due to the interplay between the elastic modulus of the structural material and the mass density of the liquid sample, enabling the precise density measurement at various temperatures. Using this capability, volume contraction of ethanol–water binary mixtures were measured with a ∼0.5 pL sample volume at different temperatures. The obtained volume contraction maximizes at a certain mole fraction and also strongly depends on temperature. The volume contraction rate per temperature broadly changes from positive to negative depending on the ethanol–mole fraction, e.g., 5.25 × 10−3%/°C at 0.042, 1.8 × 10−3%/°C at 0.074 and −16.79 × 10−3%/°C at 0.207 ethanol–mole fraction, respectively.