Dual-enhanced fluorescent biosensors using metal-coated piezoelectric nanoimprinted substrates

The integration of piezoelectric polymers with metallic nanostructures provides new opportunities for developing highly responsive fluorescent sensing devices. In this work, we show that nanoimprinted poly(vinylidene fluoride) thin films coated with a thin gold layer can amplify the fluorescence signal of Cy3-labelled DNA and improve detection sensitivity. Signal enhancement is assigned to both the surface plasmon resonance of the nanofeatures as well as to the piezoelectric-based enhancement of fluorescence when a mechanical pressure is applied to the substrate. Our study also reveals that moderate mechanical force maximises the piezoelectricity-based enhancement, while larger forces degrade the substrate. This highly sensitive platform was shown to possess good selectivity as evaluated through exposure to non-complementary sequences, as well as good reusability through ozone UV cleaning. The work highlights the potential of hybrid metal-coated and nanoimprinted piezoelectric substrates as a promising platform for highly sensitive and selective biosensors.