Integrated microfluidic dynamic potential-modulated SERS chip with high sensitivity and self-cleaning

Abstract

Surface-enhanced Raman scattering (SERS) technology faces several challenges in real-world applications, including low sensitivity, irreversible contamination of the substrate leading to poor cyclic stability, and difficulties in achieving integration of complex detection processes. To address these challenges, we propose a microfluidic-SERS integrated detection chip with dynamic potential modulation, enabling a complete “detection–self-cleaning–re-detection” closed-loop operation. Firstly, a high-sensitivity core-shell Ag@SiO₂ substrate was prepared using chemical reduction, achieving a detection limit of 10⁻¹² mol/L for Rhodamine 6 G (R6G) (AEF = 5.7 × 10⁹). Plasma surface cleaning was then applied to bond polydimethylsiloxane (PDMS) microfluidic channels with screen-printed electrodes (SPEs), resulting in the construction of a microfluidic-SERS chip with dynamic potential modulation. By applying a positive potential (+2.0 V/10 s), target molecules were desorbed from the metal nanoparticle gaps on the SERS substrate, and a metastable metal oxide layer of a certain thickness was formed. Subsequently, a negative potential (−1.2 V/15 s) was applied to remove part of the metal oxide layer, realizing in-situ regeneration of Raman hotspots and rapidly driving probe molecule enrichment. After eight cycles of detection, the signal strength remained high. Additionally, this platform can precisely identify multi-molecule mixtures (R6G/CV/MG) and has been successfully applied to the detection of uric acid molecules. Its on-site detection capability was further validated in a portable system, providing an innovative solution for rapid detection in complex real-world environments.