Recent advancements in acoustofluidic technology have paved the way for groundbreaking methods in the isolation and detection of small extracellular vesicles (sEVs). This innovative approach addresses the longstanding challenges of rapid and high-sensitivity analysis of low-volume clinical samples, which traditionally require cumbersome preprocessing and large-scale equipment.
By integrating sharp-edge microstructures with acoustically induced vortices, researchers have developed a method for size-selective concentration of target-bound complexes, enabling immediate fluorescence readout. “The acoustofluidic chip leverages localized acoustic streaming to spatially separate microbead-sEV conjugates from unbound nanoparticles, achieving a six-fold signal enhancement for EGFR-positive sEVs in just 20 minutes,” explained study author Tony Jun Huang.
Innovative Design and Functionality
The newly developed platform combines several cutting-edge components: antibody-functionalized microbeads for specific sEV capture, sharp-edge-induced acoustic vortices to concentrate bead-sEV complexes, and on-chip fluorescence quantification via microscopy. “This integrated solution provides a portable, low-cost alternative to traditional methods like Western blotting, eliminating complex preprocessing while processing samples as small as 50 µl,” emphasized the authors.
The device consists of a PDMS microchannel embedded with sharp-edge structures, activated by a piezoelectric buzzer to generate controlled fluid dynamics for targeted sEV isolation and detection. Acoustofluidic devices exploit the interaction between sound waves and microstructures to manipulate particles. Sharp-edge geometries amplify localized acoustic streaming velocities, creating vortices that trap large particles (>1 µm) while allowing nanoparticles (<400 nm) to flow freely.
Mechanics and Validation
According to COMSOL simulations, the synergy between acoustic radiation force (centripetal) and drag force (tangential) enables stable trapping of bead-sEV aggregates at vortex centers. When activated (90 Vpp, 4 kHz), 5-µm beads rapidly concentrate at microstructure tips within 120 seconds, while 400-nm nanoparticles remain dispersed—validated via real-time fluorescence imaging.
To validate its clinical utility, EGFR-positive sEVs from HeLa cells were captured using anti-EGFR-coated beads and loaded into the device. Acoustofluidic enrichment yielded a fluorescence intensity ratio (FIR) of 6.00 ± 0.46, significantly higher than EGFR-negative controls (1.01 ± 0.03, P = 0.010). Specificity was confirmed using anti-CD63 beads (positive control) and IgG beads (negative control).
Implications and Future Directions
The platform’s modular design allows for the switching of biomarkers by simply altering bead surface antibodies, enabling adaptable detection of diverse sEV subpopulations. Compared to Western blotting, which can take over five hours, the device reduces hands-on time to just 20 minutes while maintaining high specificity.
However, current limitations include suboptimal signal uniformity across microstructure tips and restricted multiplexing capacity. Future work will focus on developing parallelized channels for simultaneous multi-marker analysis and integration with downstream molecular profiling. Collectively, this acoustofluidic technology offers a transformative tool for point-of-care sEV-based diagnostics, advancing liquid biopsy applications in cancer and organ health monitoring.
Research and Funding
The research team, comprising Jessica F. Liu, Jianping Xia, Joseph Rich, Shuaiguo Zhao, Kaichun Yang, Brandon Lu, Ying Chen, Tiffany Wen Ye, and Tony Jun Huang, received financial support from the National Institutes of Health, National Science Foundation, and the Shared Materials Instrumentation Facility at Duke University.
Their work, titled “An Acoustofluidic Device for Sample Preparation and Detection of Small Extracellular Vesicles,” was published in the journal Cyborg and Bionic Systems on July 17, 2025, under DOI: 10.34133/cbsystems.0319.
