Monolithic Acoustic Droplet Centrifuge Array for Enhancing Point-of-Care Detection of Trace MicroRNAs

MicroRNAs (miRNAs) are considered as critical biomarkers for early tumor diagnosis, yet conventional detection methods are limited in sample throughput, sensitivity, automation, and broader applicability. A promising approach for achieving a point-of-care detection platform involves the integration of physical pretreatment and biological sensing within a single microfluidic chip. Herein, we introduce a monolithic acoustic droplet centrifuge module featuring nine miniaturized units, which enables the efficient enrichment of tumor cells and trace biomarkers within droplet arrays. This design not only streamlines multiple steps in miRNA detection processes but also significantly enhances analytical sensitivity. Such an innovative spiral surface acoustic wave array (SAWA) incorporates a space-efficient architecture that maximizes channel density on miniaturized substrates, enabling parallel high-throughput processing for particle/cell enrichment/separation and droplet centrifugation. We demonstrate that a single SAWA activation signal synchronized the multiple droplets control, enabling simultaneous centrifugation and detection processes of up to nine droplets on a 13 cm² chip. Compared to the routine miRNA detection process using monodispersed particles, our SAWA-based approach improves fluorescence signal sensitivity by enriching functionalized particles, achieving the limit of detection down to 10^-14 mol/L. Therefore, such SAWA platform offers significant potential to advance early cancer diagnostics.