Programmable Acoustic Wetting (PAW) Microfluidics for Protein Biomarker Detections

Non-invasive diagnostics require ultra-sensitive detection of low-abundance protein biomarkers in biofluids such as saliva or urine for early disease detection and monitoring of minimal residual disease (MRD). Many clinically relevant biomarkers associated with cancer,neurological disorders, and early-stage infections circulate at extremely low concentrations, often below 10⁻¹⁶ M and approaching attomolar levels (10⁻¹⁸ M), which remain difficult to detect using conventional immunoassays. Although emerging technologies such as digitalELISA and droplet-based assays have improved sensitivity by confining molecules within small reaction volumes, challenges remain in achieving higher sensitivity, precise fluid control, and efficient multiplexed detection. Here, we propose a microfluidic Programmable Acoustic Wetting (PAW) platform for ultra-sensitive single-molecule protein detection and highthroughput diagnostics. PAW employs acoustic forces to transport microbeads across water–oil interfaces, enabling ultrathin fluidic encapsulation that confines molecules within ~30 fL reaction volumes—approximately 50× smaller than droplet-based ELISA. This extreme molecular confinement increases local biomarker concentration and enables detection sensitivities down to 10⁻¹⁷ M. The platform further integrates multiplexed barcoded microbeads and AI-assisted optical screening to analyze up to 10⁵ beads within 40 minutes with nearly 100% sampling efficiency. We will demonstrate non-invasive detection of key lung cancer biomarkers (e.g., CEA, Cyfra21-1, NSE, SCC, and ProGRP) from saliva samples. Overall, PAW provides a transformative platform for rapid, multiplexed, and ultra-sensitive biomarker detection, advancing non-invasive diagnostics and precision medicine.