Conferring plasmonic properties in PDMS based substrate with plasma synthesized Ag nanoparticles: assessment and challenges.

Impregnating nanoparticles in classical polymer substrata is one of the interesting strategies which may confer multi-functional and multi-purposed polymer-based structure. The potential applications extend from bio-compatible scaffold for different types of tissue growth [1], antimicrobial or antifouling surface layer [2], or even photocatalytic framework for enhanced reactional sites [3]. Nanoparticles aglomeration remains however a major concern during the fabrication of these “enhanced polymer substrate”. Recent work in our research group have shown promising rapid plasma synthesized Ag and Au nanoparticles with tuneable geometry, with furthermore a safe-by-design process [4]. Intermediate steps involving hazardous nanoparticles powder blending or dilution may be forsaken to incorporate the nanoparticles in polymer substrata. In this work, we incorporated the plasma synthesized Ag nanoparticles within a PDMS based microfluidic circuit. The microfluidic circuit is destined to offer eventual benchwork for fast photo-catalytical or antimicrobial activities evaluation. Optical spectroscopy measurements have been performed where the non-reflected and non-transmitted incident light were analyzed to attest the surface plasmon or localized plasmon band excitation. Contrary to classical analysis where non-transmitted incident light in the plasmon band is assimilated to the general term “plasmon absorption”, we succeeded in distinguishing cases where localized plasmon or propagating surface plasmon mode were excited. Herein the plasmon wavelength (400 – 450nm), the same level of non-transmitted light could be assorted with distinct levels of non-reflected light, giving key information on the migration and aggregates formation of AgNP within the PDMS substrate. The results also confirmed that the AgNP incorporation is subjected to aggregates formation with time.