Thick polystyrene-coated quartz crystal microbalance as a basis of a cost effective immunosensor

The use of a commercial quartz crystal microbalance for a disposable low cost and reliable immunosensor is presented. By thick polystyrene coating, the oxidation problem of the commercial quartz crystal electrode is avoided and the coating provides a physical adsorption scheme to immobilise antigens or antibodies. The coating doesn't contribute significantly to the damping effect. This is important for applications in liquids. Using the modified quartz, the physical adsorption of protein is well achieved. The frequency decrease caused by specific reactions between insulin, anti-insulin antibody, and anti-mouse IgG antibody is presented as an example. A frequency shift caused by non-specific reactions is not detected.