Electrically Controlled Enrichment of Analyte for Ultrasensitive SERS-Based Plasmonic Sensors

Abstract

Recently, sensors using surface-enhanced Raman scattering (SERS) detectors combined with superhydrophobic/superhydrophilic analyte concentration systems showed the ability to reach detection limits below the femto-molar level. However, a further increase in the sensitivity of these sensors is limited by the impossibility of the concentration systems to deposit the analyte on an area of less than 0.01 mm2. This article proposes a fundamentally new approach to the analyte enrichment, based on the effect of non-uniform electrostatic field on the evaporating droplet. This approach, combined with the optimized geometry of a superhydrophobic/superhydrophilic concentration system allows more than a six-fold reduction of the deposition area. Potentially, this makes it possible to improve the detection limit of the plasmonic sensors by the same factor, bringing it down to the attomolar level.

Multifunctional superhydrophobic platform for control of water microdroplets by non-uniform electrostatic field

“…The working area used directly for manipulating droplets is located on the upper surface of the substrate. An array of micropillars with multimodal roughness is created on it by laser structuring [21][22][23] . This makes it possible to achieve superhydrophobic properties of working area with a contact angle θ~155°.…”

Multifunctional Superhydrophobic Platform for Control of Water Microdroplets by Non-Uniform Electrostatic Field

“…The working area used directly for manipulating droplets is located on the upper surface of the substrate. An array of micropillars with multimodal roughness is created on it by laser structuring [21][22][23]. This makes it possible to achieve superhydrophobic properties of working area with a contact angle θ~155 • [24,25].…”

Plasma‐Etched Nanograss Surface without Lithographic Patterning to Immobilize Water Droplet for Highly Sensitive Raman Sensing

“…However, typical state‐of‐the‐art superhydrophobic surfaces are slippery with low sliding angles for droplets. Therefore, they need to be positioned using lithographic patterning processes [ 18,19,21 ] (i.e., optical lithography, [ 22 ] e‐beam lithography, [ 6 ] laser writing, [ 23 − 25 ] laser printing, [ 26 ] and particle assembly) [ 27 ] to locate the droplets, which renders the fabrication process complex, expensive, and time‐consuming. Although most superhydrophobic surfaces are slippery, sticky (adhesive) superhydrophobic surfaces have also been reported.…”