Single step, mould-free fabrication of polymer optical waveguides for localized surface plasmon resonance based sensing platform

Novel U-shaped, polymer optical waveguides are demonstrated as localized surface plasmon resonance (LSPR) based sensors for various biosensing applications. Commercially available materials like polyester overhead projector sheets (OHP), poly (methyl methacrylate) (PMMA) and acrylonitrile butadiene styrene (ABS) were effectively deployed as core materials for fabrication of optical waveguides, due to their malleability and excellent combination of optical and mechanical properties. Single-step fabrication of waveguides has been achieved using simple tools like 3D printer and laser cutting technology, rather than utilizing moulds or clean room facilities. Resilient and repeatable bio-functionalization of waveguides with successful immobilizing of gold nanoparticles (GNP) was obtained on the waveguide surface. The sensor response for each of the fabricated polymer waveguides was characterized by evaluating the bulk refractive index (RI) sensitivity. Highest refractive index sensitivity of 14.79.A/RIU was obtained for GNP immobilized PMMA waveguides. A biosensing application using an affinity based labelled assay was demonstrated on PMMA waveguides. Limit of detection (LOD) of 0.25 mu g/mL was achieved with a non-specific response of only 5.3%. The proposed LSPR based polymer optical waveguide sensor is inexpensive, robust and provides a platform for point of care detection system.