Large-Scale, Lithography-Free Production of Transparent Nanostructured Surface for Dual-Functional Electrochemical and SERS Sensing.

Journal: ACS Sensors
Published:
Abstract

In this work, we present a dual-functional sensor that can perform surface-enhanced Raman spectroscopy (SERS) based identification and electrochemical (EC) quantification of analytes in liquid samples. A lithography-free reactive ion etching process was utilized to obtain nanostructures of high aspect ratios distributed homogeneously on a 4 in. fused silica wafer. The sensor was made up of three-electrode array, obtained by subsequent e-beam evaporation of Au on nanostructures in selected areas through a shadow mask. The SERS performance was evaluated through surface-averaged enhancement factor (EF), which was ∼6.2 × 105, and spatial uniformity of EF, which was ∼13% in terms of relative standard deviation. Excellent electrochemical performance and reproducibility were revealed by recording cyclic voltammograms. On nanostructured electrodes, paracetamol (PAR) showed an improved quasi-reversible behavior with decrease in peak potential separation (ΔEp ∼ 90 mV) and higher peak currents (Ipa/Ipc ∼ 1), compared to planar electrodes (ΔEp ∼ 560 mV). The oxidation potential of PAR was also lowered by ∼80 mV on nanostructured electrodes. To illustrate dual-functional sensing, quantitative evaluation of PAR ranging from 30 μM to 3 mM was realized through EC detection, and the presence of PAR was verified by its SERS fingerprint.

Authors
Kuldeep Sanger, Onur Durucan, Kaiyu Wu, Anil Thilsted, Arto Heiskanen, Tomas Rindzevicius, Michael Schmidt, Kinga Zór, Anja Boisen