Light-induced foldable materials with 3D-gold nanorod assemblies enable large area plasmonic hot-spot generations

Abstract

Foldable platforms have huge potential in the field of plasmonic engineering thanks to their ability to dynamically reconfigure surface geometries, enabling precise spatial control over nanoscale electromagnetic interactions. Herein, we demonstrate the design and fabrication of light-induced foldable polystyrene (PS) platforms functionalized with plasmonic nanostructures for dynamic control of electromagnetic hot-spot generation and surface-enhanced Raman scattering (SERS) applications. The self-folding behavior of the platforms was actuated via infrared (IR) irradiation, with folding angles modulated by hinge geometry and exposure time. Multi-armed PS platforms were engineered to transform from 2D to 3D configurations, enabling precise spatial localization of analyte molecules through geometric reconfiguration. Plasmonic hot-spot generations were investigated by decorating the platform surfaces with colloidal gold nanoparticles (AuNPs), nanourchins (AuNOs), and nanorods (AuNRs), as well as through the integration of 3D-oriented AuNR assemblies fabricated via the oblique angle deposition method. SERS measurements using methylene blue (MB) demonstrated substantial signal enhancements upon folding, with 3D-AuNR assemblies yielding superior performance due to their anisotropic and ordered architecture. A proof-of-concept application of pesticide detection from a tomato surface validated the integrated platform's capabilities for remote actuation, target collection, and ultrasensitive detection. This work highlights the potential of programmable polymeric actuators as scalable, untethered sensing devices for real-world analytical applications.