Novel PDMS leaky waveguide with self-assembled gold nano-particles for ssDNA detection

This paper presents a novel method to fabricate gold nano-particle (NP) coated PDMS waveguides for localized surface plasmon resonance (LSPR) detection of biosamples. In the presented method, PDMS optical waveguide is firstly cast in a Teflon tubing to form a cylindrical leaky waveguide structure. The de-molded PDMS optical waveguide is then modified with PDDA molecules and deposited a layer of 13 nm gold nano particle for inducing LSPR effect. The fabricated LSPR sensor is finally connected to multi-mode optic fibers for guiding the detection light. The measured sensitivity of the PDMS waveguide based LSPR sensor for detecting diluted glycerol solutions is 7.25 AU/RIU or 325.97 nm/RIU, respectively. Experimental results of a label-free detection of DNA hybridization show that the presented PDMS waveguide based LSPR sensor has a good linear response and has a detection limit of about 10 pM, confirming the detection performance of the developed PDMS waveguide-based LSPR sensor.