Beyond traditional SERS: Integrating pH control and renewable screen-printed electrode for EC-SERS detection

Surface-enhanced Raman spectroscopy (SERS) for small, weakly adsorbing pesticides is limited by insufficient analyte enrichment and poor field deployability. To address this limitation, we present a portable electrochemical SERS (EC-SERS) platform that integrates a redox-roughened screen-printed silver electrode (SPE-Ag) with a smartphone-controlled mini-potentiostat. At pH 2, imidacloprid (IMI) is protonated, and applying -1.0 V drives IMI toward plasmonic "hot spots", yielding a 27-fold signal enhancement and a limit of detection (LOD) of 1.5 nM, four orders of magnitude lower than conventional SERS (13.5 μM). The self-fabricated, renewable SPE-Ag tolerates more than 15 adsorption-desorption cycles and exhibits good reproducibility (inter-batch RSD 5.6%), uniformity (intra-chip RSD 5.8%), and stability (90% signal retention over 10 weeks). Spiked samples of Pisum sativum L. and Allium fistulosum L. showed recoveries of 90.65%-103.04%. Overall, this low-cost, portable EC-SERS platform enables rapid screening of pesticide residues in real food matrices, showing strong potential for food safety monitoring.