Fully Microfabricated Surface Acoustic Wave Tweezer for Collection of Submicron Particles and Human Blood Cells

Precise manipulationof (sub)-micron particles is keyfor the preparation,enrichment, and quality control in many biomedical applications. Surfaceacoustic waves (SAW) hold tremendous promise for manipulation of (bio)-particlesat the micron to nanoscale ranges. In commonly used SAW tweezers,particle manipulation relies on the direct acoustic radiation effectwhose superior performance fades rapidly when progressing from micronto nanoscale particles due to the increasing dominance of a secondorder mechanism, termed acoustic streaming. Through reproducible andhigh-precision realization of stiff microchannels to reliably actuatethe microchannel cross-section, here we introduce an approach thatallows the otherwise competing acoustic streaming to complement theacoustic radiation effect. The synergetic effect of both mechanismsmarkedly enhances the manipulation of nanoparticles, down to 200 nmparticles, even at relatively large wavelength (300 mu m). Besidesspherical particles ranging from 0.1 to 3 mu m, we show collectionsof cells mixed with different sizes and shapes inherently existingin blood including erythrocytes, leukocytes, and thrombocytes.

Automated summary

Precise manipulation of (sub)-micron particles is crucial in many biomedical applications, and surface acoustic waves (SAW) show great promise for this purpose. In commonly used SAW tweezers, particle manipulation relies on the direct acoustic radiation effect, which becomes less effective for nanoscale particles due to the dominance of a second-order mechanism called acoustic streaming. By utilizing stiff microchannels and precise control, we introduce an approach that combines acoustic streaming with the acoustic radiation effect, resulting in enhanced manipulation of nanoparticles even at relatively large wavelengths.