Highly Efficient Coreactant-Free Electrochemiluminescence Sensing Platform Using Novel Microfabricated Multiplexed Entwined Spiral Microelectrodes for Point-of-Care Applications

Luminol-based Electrochemiluminescence (ECL) generates weak signals in neutral media and typically requires H2O2 as a coreactant. However, H2O2 instability and the need for on-site addition hinder real-time diagnostic applications. Compact integrated sensing platforms are ideal for point-of-care (POC) testing due to portability, low sample requirements, and multiplexing. However, as sensor dimensions decrease, the low light emission issue in ECL becomes severe. We introduce a novel fully integrated miniaturized silicon device consisting of three sensors comprised of unique entwined micro-spiral electrodes in a generator-collector configuration. This enables highly sensitive, coreactant-free multiplexed sensing at physiological pH by accelerating in-situ reactive oxygen species production and boosting ECL intensity. Systematic optimization of electrode geometry (gaps and widths) yields an 11-fold improvement in ECL signal compared to a single-electrode setup, as well as excellent reproducibility and stability. In addition to Trolox and H2O2 detection, the platform demonstrates multiplex immunosensing through selective functionalization of the collector electrodes with chitosan nanocomposites, followed by Protein A/G-assisted immobilization of anti-IgG antibodies with peptide-based antifouling. The immunosensors exhibit high analytical performance (linear range: 0.001-100 pg{middle dot}mL-1, detection limit: 0.8 fg{middle dot}mL-1) with excellent reproducibility and reliability in 25% fetal bovine serum, highlighting the platforms potential for sensitive, coreactant-free multi-analyte POC diagnostics.