This article reports an improved separation method for the isolation of sperm cells from dilute, “large volume” samples that contain female DNA, using bead-assisted acoustic trapping.
In an enclosed glass–PDMS–glass (GPG) resonator, researchers used a three-layer microfluidic architecture to generate “trapping nodes” in ultrasonic standing waves. They investigated the dependence of trapping efficiency on particle concentration for both sperm cells and polymeric beads. After determination of the critical concentration of polymeric beads required to seed the trapping event, sperm cells in dilute solution are trapped as a result of the enhanced secondary radiation force (SRF). Sperm-cell-containing samples with volumes up to 300 μL and cell concentrations as low as ∼10 cells/μL are amenable to effective trapping in the presence of an abundance of female DNA in solution. Complete processing of samples is accomplished with separation of the female and male fractions within 15 min. This project demonstrates that the collected fractions are amenable to subsequent DNA extraction, short tandem repeat PCR, and the generation of STR profiles for the isolated sperm cells. (publisher abstract modified)