Poly(2-Hydroxyethyl methacrylate-co-N,N-dimethylacrylamide)-Coated Quartz Crystal Microbalance Sensor: Membrane Characterization and Proof of Concept.

Application-oriented hydrogel properties can be obtained by modifying the synthesis conditions of the materials. The purpose of this study is to achieve customized properties for sensing applications of hydrogel membranes based on poly(2-hydroxyethyl methacrylate), HEMA and N,N-dimethylacrylamide, DMAa. Copolymer p(HEMA-co-DMAa) hydrogels were prepared by varying the DMAa monomer ratio from 0-100% in 20% increments. Hydrogel membranes were characterized by attenuated infrared spectroscopy. Swelling and sorption were evaluated using cation solutions. Copolymers were also synthesized on the gold surface of quartz crystal microbalances (QCM) as coating membranes. A proof of concept was conducted for approaching the design and development of QCM sensors based on P(DMAa-co-HEMA)-membranes. Results showed that the water and ion adsorption capacity of hydrogel membranes increased with higher DMAa content. Membranes are not selective to a specific location but did show different transport features with each cation. The QCM coated with the selected membrane presented linear relationships between resonance frequency and ions concentration in solution (10-120 ppm). As a consequence, hydrogel membranes obtained are promising for the development of future biosensing devices.