Exploratory Data Analysis of Bulk Fluid Viscosity Measurements by Means of Quartz Cyrstal Microbalance Impedance Analysis

Quartz Crystal Microbalance (QCM) is a mass sensitive biosensor, which can also be used in liquid medium to study viscoelastic modeling of thin films and bulk fluids. The most informative technique in evaluation of QCM measurements is impedance analysis as it describes the electrical behavior of the resonator in detail. Resistance, reactance, conductance, susceptance, phase angle and absolute impedance are impedance parameters that have been used to analyze QCM data. The aim of this study is to apply exploratory data analysis (EDA) methods on understanding the relationship of these parameters with bulk fluid viscosity using glycerol concentration. According to the results, phase angle and reactance are significantly less correlated to viscosity changes compared to other parameters (Pearson Correlation Coefficients, PCC) and explained variance of the dataset is above $90 \%$ with 3 components (Principal Component Analysis). This indicates conventional modeling of viscosity using a single (frequency change only, $\Delta \text{f}$) or two parameters ($\Delta \text{f}$ and $\Delta \text{D}$) might be inadequate in explaining the viscosity change.