Decoration of Nanoenabled Optoplasmonic Sensors on Flexible Micropatterned Surfaces

Metal nanoparticles, such as gold or silver, with varying shapes, sizes, surface properties, and assemblages, show plasmonic properties, such as localized surface plasmon resonance, which has been widely employed for the point-of-care sensing of various disease markers in the biofluids. The present study focuses on the development of a refractive index (RI) sensor decorated on a micropatterned flexible substrate. A soft lithography technique has been employed for the replica molding of the patterns present on a compact disk surface onto a flexible polydimethyl siloxane (PDMS) substrate. Furthermore, plasmonic gold nanoparticles (AuNPs) are immobilized on the same to infuse plasmonic signals on the micropatterned surface. A comparative analysis between the flat, 1-D stripe-patterned, and 2-D box-patterned surfaces shows the potential of the micropatterned surfaces in displaying a larger variation in the plasmonic signals in the presence of an analyte in the surrounding medium. The UV-visible characterization of the micropatterned substrate discloses a larger variation in the absorbance and a larger shift in the wavelength in the presence of different concentrations of bioanalytes in the surrounding media. For example, a significant increase in absorbance was observed when different bovine serum albumin (BSA) concentrations were dispensed in the surroundings of this surface, indicating the substrate’s potential to sense critical biomarkers. Computational fluid dynamic (CFD) simulations have been performed to emulate and explain the experimental observations. The proposed nanoenabled micropatterned optoplasmonic sensor (n-
$\mu $
OS) shows a significant potential to translate into point-of-care devices with a significantly higher localized surface plasmon resonance (LSPR) sensitivity.