Acoustofluidic manipulation of nanoparticles to suppress coffee-ring effects

Acoustic manipulation of particles can be used to facilitate characterization of bionanoparticles relevant to biomedical and pharmaceutical applications. This study introduces acoustofluidic strategies that concentrate nanoparticles using interdisciplinary methods involving fluids, acoustics, and interfacial dynamics. A droplet-based acoustofluidic device combines surface acoustic waves with microgrooves on Polydimethylsiloxane (PDMS) to reduce the coffee-ring effect. It generates acoustic streaming and radiation forces that cause nanoparticle aggregation at the droplet’s center, while microstructures help maintain contact angles and promote uniform deposition. The device's reusability is enhanced as the droplet holder is not permanently bonded with epoxy or plasma. Consequently, the reusability of the device reduces the cost of fabricating piezoelectric devices. These results offer a hybrid framework for acoustic-assisted analyte concentration with potential applications in microarray fabrication, biosensing, pharmaceutical quality control, and process analytical technology.