Design of a novel disposable piezoelectric co-polymer diaphragm based biosensor unit

Piezoelectric biosensors represent an economic alternative suitable for the detection of a variety of biomolecules. However, the difficulty of forming diverse structures and shapes using conventional piezoelectric ceramic and quartz crystals has so far limited their potential applications. Piezoelectric polymers and their co-polymers are considered as the favourable choice in the fabrication of different types of sensors due to their low cost, light weight and ease in forming delicate shapes. This paper demonstrates a disposable and simple piezoelectric diaphragm sensing platform consisting of a flexible co-polymer thin film and plastic sample holder. To test this platform, protein A was immobilized to form a bridge between goat immunoglobulin G (IgG) probe molecules and the gold electrode on the surface of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] film. The designed polyetheretherketone sample holders were applied to fix the piezoelectric co-polymer films. The apparatus was successfully used as an immunosensor and had the added advantage that the co-polymer thin film could be replaced. Optimum concentration of goat IgG probe molecules for fabricating the immunosensors was determined to be 3 mg/mL. The P(VDF-TrFE)-based immunosensor of this type shows a good reproducibility and a broad dynamic detection range.