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 H ₂ O ₂ as a coreactant. However, H ₂ O ₂ 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 H ₂ O ₂ 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·mL ⁻¹ , detection limit: 0.8 fg·mL ⁻¹ ) with excellent reproducibility and reliability in 25% fetal bovine serum, highlighting the platform’s potential for sensitive, coreactant-free multi-analyte POC diagnostics.