Scientists at Duke University have developed a way of concentrating nanoparticles inside a small device using only sound waves. This achievement may help introduce portable diagnostics that rely on attaching nanoparticles to biomarkers such as proteins and measuring how many find their targets. Nanoparticles tagged with fluorescent markers to make them easier to see are concentrated in a column by a new acoustic whirlpool device.
There is now a large selection of nanoparticles, and ways to attach them to different biomolecules, but separating them from the sample is still a challenge that typically requires bulky equipment operated by trained technicians.
The new acoustofluidic chip is small enough to be integrated into hand-held devices and uses only five volts for power. From the study abstract in journal ACS Nano:
"Numerical simulations were used to elucidate the mechanism of the single vortex formation and were verified experimentally, demonstrating the focusing of silica and polystyrene particles ranging in diameter from 80 to 500 nm. Moreover, the acoustofluidic chip was used to conduct an immunoassay in which nanoparticles that captured fluorescently labeled biomarkers were concentrated to enhance the emitted signal. With its advantages in simplicity, functionality, and power consumption, the acoustofluidic chip we present here is promising for many point-of-care applications".