Development of Screen-Printable Nafion Dispersion for Electrochemical Sensor

A modified Nafion dispersion for direct screen printing was developed and characterized. Commercial Nafion solution was neutralized to its sodium form and the solvent was replaced by a screen-printing-compatible solvent. The modified Nafion dispersion has optimized rheological properties including shear-thinning behavior, thixotropy, and moderate yield stress. The elemental composition and chemical states of the modified Nafion were characterized by X-ray photoelectron spectroscopy (XPS). The chemical state and composition of the modified Nafion remained the same as those of commercial Nafion. The crystallinity of the cured membranes of both Nafion dispersions was evaluated by X-ray diffraction spectroscopy (XRD). It was found that the modified Nafion has lower crystallinity as compared to the commercial Nafion, and the degree of crystallinity increases with an increase in the curing temperature. The modified material was screen printed onto a commercial sensor as a cation-exchange membrane for the detection of lead Pb(II) in buffer solutions. The sensor showed good linearity in the range of 5 mu g/L to 500 mu g/L, with a detection limit of 2 mu g/L for Pb(II) by square-wave anodic stripping voltammetry. This work demonstrates the possibility of printing Nafion on a large scale in a wide range of fields, such as printed electrochemical sensors.