Aqueous liquids have a wide range of applications in many fields. Basic physical properties like the density and the viscosity have great impacts on the functionalities of a given ionic liquid. For the millions kinds of existing liquids, only a few have been systematically measured with the density and the viscosity using traditional methods. However, these methods are limited to measure the density and the viscosity of an ionic liquid simultaneously especially in processing micro sample volumes. To meet this challenge, we present a new theoretical model and a novel method to separate density and viscosity measurements with single quartz crystal microbalance (QCM) in this work. The agreement of experimental results and theocratical calculations shows that the QCM is capable to measure the density and the viscosity of ionic liquids.

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In time-interleaved analog-to-digital converter (ADC) architecture, offset mismatch, gain mismatch, and timing error between channels degrade the performance of time-interleaved ADCs. This paper focuses on the timing error, and proposes a simple calibration algorithm based on Hilbert transform estimate and then correct the timing error. With a cosine input, it could efficiently and accurately estimate the timing error. Fractional delay filters are developed to correct the timing errors. This simplifies the design and decreases the cost. Numerical simulations are used to verify the proposed estimation and correction algorithm.

As an ultra-sensitivity sensor, a quartz crystal microbalance (QCM) could be used to quantitatively characterize the relation between QCM parameters and the characteristics of viscoelastic films. When a QCM coated with a viscoelastic thin film is in the gas phase, based on the constructive equation of the quartz crystal and ignoring the capacitance effect, the equivalent Butterworth–Van Dyke (BVD) model of the QCM and the explicit expression for its frequency shift are derived. The “extra mass effect” deduced by the complex modulus is also obtained. It is found that the tendency of the BVD model in this work agrees well with that of Voinova’s model, although both are derived in different ways. Meanwhile, it can be seen that the two above-mentioned models exhibit different characteristics when compared with Sauerbrey’s model and Arnau’s model. The BVD model will help analyze the properties of viscoelastic films in the gas phase.

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