Flexible nanoimprinted substrate integrating piezoelectric potential and photonic-plasmonic resonances†

Abstract

Flexible substrates for sensing provide adaptable, lightweight, and highly sensitive platforms for detecting different substances. The flexibility of these substrates allows for seamless integration with complex shapes and dynamic surfaces, enabling monitoring in challenging conditions using methods such as surface-enhanced Raman spectroscopy (SERS). Here we outline a flexible metamaterial array sensor formed from plasmonic silver-coated nanoimprinted piezoelectric polyvinylidene fluoride film. We show that nanoscale array features can be prepared on the surface of the piezoelectric film using a facile nanoimprinting procedure. These nanoimprinted features act as polarization channels that enable plasmonic resonances, enhancing the SERS signal strength and improving reproducibility. We combine this effect with the inherent piezoelectric properties of polyvinylidene fluoride to further enhance the Raman signal strength upon mechanical deformation. Our results demonstrate a significant enhancement of the SERS signal when probed at a wavelength of 532 nm, achieving over an order of magnitude increase in signal strength for a range of analytes. This lightweight and flexible SERS substrate holds significant potential for applications in medical diagnostics, environmental monitoring, and trace detection, offering a highly sensitive and reproducible analytical platform.