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.
Highlights
Performance plasmonic sensors may be significantly increased by a targeted deposition of analyte molecules on the surface of a sensitive element
The analytical and numerical data are in good agreement in the region of small values of d2 and begin to diverge where this diameter becomes comparable to the diameter of the lower electrode d1
If the diameter d2 is chosen near the lower value from this range, electric field lines will be too concentrated near the upper electrode, which can lead to a local electrical breakdown of the adjacent air layer
Summary
Biochemistry and medicine require the development of techniques that allow us to carry out express detection substances in their aqueous solutions at an ultra-low concentration [1–7]. Significant attention in these studies is paid to plasmonic sensors [4–13], mainly due to their non-invasiveness and ultra-high sensitivity [11,14–18]. Operation of these types of sensors is based on the phenomenon enhancement of Raman response from analyte molecules near “hot spots” at special nanostructures [19–21]. The analyte molecules are not always located near the enhanced regions
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