Portable, quantitative, real-time isothermal nucleic acid amplification test using microfluidic device-coupled UV-LED photodiode detector

We report a stand-alone, automated, fully quantitative, and portable Microfluidics Integrated LED-Photodiode (MILP) sensing technology as a new molecular diagnostic platform for rapid point-of-care nucleic acid testing in real-time. The all-in-one device integrates a paper-based assay for nucleic acid purification using a polymer-based membrane filter, in-situ isothermal amplification, dual-mode optical detection, and fully quantitative signal analysis by capturing the photovoltaic response using electrical polarity and photocurrent measurements. Highly selective photovoltaic cut-offs may readily recognize test-gene-specific variations quantitatively without requiring further auxiliary instrumentation. The on-cartridge limit of detection (LoD) showed 10 copies/μL, which could diagnose SARS-CoV-2 samples with high clinical sensitivity (95%) and specificity (100%) with reference to real-time PCR-based gold-standard benchmark. Our findings emphasize the test's unique advantages for intensive health surveillance, enabling early disease screening, precise severity assessment, and real-time tracking of disease progression in resource-limited settings without the need for extensive and expensive laboratory infrastructure.