Scalable device architectures for acoustofluidic separation, isolation, and enrichment in biomedical research

We report a highly configurable acoustofluidic technology for separation, isolation, and enrichment of micro-/nanoscale objects, operations that are critical to advancing biological and biomedical research. Decoupling motion of target species from non-target mixture constituents opens opportunities for novel studies involving in situ analyses or downstream processing. Acoustic microfluidics provide such precise control by exploiting differences in size and/or particle density and compressibility. Resultant non-contact cell separation minimizes stress on sensitive biological samples. Traditional free-flow acoustophoresis utilizes an ultrasonic standing wave oriented perpendicular to the flow direction so that particle motion is determined by the balance of the acoustophoretic force and viscous drag from the quiescent (in the transverse direction) fluid; the required separation time dictates sample flow rate and channel length, constraining throughput and device size. In contrast, we extend the longitudinal trapping approach to reorient the flow and acoustophoretic separation, eliminating such constraints. Longitudinal standing bulk acoustic wave (LSBAW) devices comprise pillar arrays forming perforated “pseudo walls” that locally augment the pressure field for particle retention at predefined locations. Such structures enable targeted enrichment in an inherently scalable and parallelizable format. Configurations for different applications are discussed, including the possibility for processing throughput exceeding 10 ml/min.