Evaluations of ethylene glycol and polyethylene glycol aqueous solutions using a hybrid sensor of surface plasmon resonance and quartz crystal microbalance

Abstract

A hybrid sensor based on surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) was prepared. One of the electrodes of the QCM sensor had a grating structure to enable SPR excitation. The SPR property was investigated through the transmission of the visible-light spectrum. The theoretical calculation showed that the experimental values almost corresponded to the theoretical ones; this suggests that the transmitted light dips were due to SPR. In order to investigate the usefulness of this hybrid sensor, the characteristics of SPR and the oscillation frequency drops of QCM (ΔF QCM) were investigated for aqueous solutions of ethylene glycol (EG) and polyethylene glycols (PEGs) with various degrees of polymerization. The position and slope of the SPR dip wavelength and the ΔF QCM curves depended on the degree of polymerization, suggesting that the sensor can be used to evaluate a solution property and/or discriminate a solute material.