Capturing molecules with plasmonic nanotips in microfluidic channels by dielectrophoresis

Abstract

Over the last decades, different concepts have been established for the use of plasmonic nanostructures in sensing applications. One challenge in this context lies in delivering the analyte of interest to the location of the nanostructures and selectively attaching it to their surfaces. Here we present a method for the collection and concentration of molecules on arrays of metallic nanocones, making use of the high electric field gradients at the nanotips. For this purpose, the nanocones are integrated into a microfluidic channel and used as nanoelectrodes. By applying an AC voltage, dielectrophoresis is used to capture molecules from the channel region near the nanocones. Simulations of the dielectrophoretic forces in the channel are presented as well as experimental proof of the proposed method. After attachment of the molecules, optical read-out techniques can directly be performed on the plasmonic nanostructures.

Recent strategies toward microfluidic‐based surface‐enhanced Raman spectroscopy

“…Another example is introduction of sheath-flow liquid focusing the sample solution to the SERS substrate [85]. An elegant way of sample capturing is the use of dielectrophoretic field generated at the substrate as described by Schäfer et al using plasmonic substrate of gold nanotips for creation of dielectrophoretic field for selective molecule capturing [86].…”

Photoinduced Temperature Gradients in Sub‐Wavelength Plasmonic Structures: The Thermoplasmonics of Nanocones

“…[34][35][36] Some of these modeling studies [21,[33][34][35][36] have observed temperature inhomogeneities in conical structures with dimension over the diffraction limit (µm-long tips), where the inhomogeneities are usually considered negligible to affect the addressed applications. [22,24] Similarly, recent sensing applications [30,37] based on arrays of ≈100 nm-long nanocones [38][39][40] have leveraged on the excitation of the characteristic EM hotspots of the nanocones while the study of their associated thermoplasmonic response was not addressed.…”

Enhancement of dielectrophoresis using fractal gold nanostructured electrodes

“…In a recent study, carbon nanotubes have been grown on flat electrodes to increase capture of titanium dioxide (TiO 2 ) nanoparticles using DEP . In another study, nanometer sized cones were used to trap BSA molecules using DEP .…”