Digital Microfluidic Chemiluminescence Immunoassay Cartridge for Automated Point-of-Care Protein Detection

Abstract

Point-of-care (POC) detection of protein biomarkers is essential for rapid clinical decision-making. We present a fully automated digital microfluidic chemiluminescence immunoassay (DMF-CLIA) cartridge that supports robust and reproducible assay workflows, including droplet generation, incubation, washing, enzymatic reaction, and chemiluminescence detection. These processes are coordinated through integrated electrical, thermal, magnetic, and optical control. The cartridge consists of a printed circuit board (PCB) bottom plate and an injection-molded polycarbonate top plate, enabling scalable and cost-effective manufacturing. By adapting standard commercial CLIA chemistry, we optimized the workflow through dynamic droplet shuttling during incubation to enhance mixing and promote efficient formation of paramagnetic particle (PMP)-antigen-reporter complexes, and a full resuspension washing protocol that achieved ∼99% PMP retention with low background signal. The DMF-CLIA system quantified cardiac troponin I (cTnI) within 12 min, achieving a limit of detection of 0.01 ng/mL, a linear dynamic range of 0.03–100 ng/mL (R2 = 0.9992), and a coefficient of variation of ∼6% at 0.03 ng/mL, meeting clinical precision criteria at the 99th percentile decision threshold. Overall, this open and flexible architecture enables the straightforward adaptation of commercial immunoassay kits and provides a practical pathway for translating established laboratory assays into decentralized diagnostic settings.