Power-free passive preconcentration cassette in lateral flow assays for enhanced sensitivity.

UNLABELLED: Lateral flow assays (LFAs) are widely used for point-of-care diagnostics because of their simplicity and affordability. However, their sensitivity remains insufficient for detecting low-abundance biomarkers, which limits their applicability in early disease detection and in resource-constrained environments. This study investigates whether a power-free passive preconcentration cassette (PPC) can enhance LFA sensitivity without compromising usability. A PPC that integrates seamlessly with commercial LFA housings was developed to enhance detection sensitivity without compromising usability. The PPC employs a Nafion-coated pin array to enable ion-selective transport during capillary-driven flow, creating a localized enrichment zone. Geometric optimization of the pin-array architecture revealed a hybrid design that balances ionic polarization with flow uniformity. When applied to PPC-LFAs for influenza A and hepatitis C detection, the platform achieved approximately a fourfold improvement in sensitivity while maintaining specificity and stable fluidic performance. This ion-selective, self-powered preconcentration strategy provides a broadly applicable, instrument-free means of improving LFA sensitivity, making it especially suitable for decentralized and self-administered diagnostic applications. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s13534-026-00598-5.