Acoustic Differential Extraction
This project highlights the use of acoustic forces in a valveless microfluidic device to trap sperm cells in the presence of female epithelial DNA obtained from sexual assault evidence.The device is comprised of two layers: a printed circuit board layer containing microtransducers, and a glass fluidic layer. An ultrasonic frequency tuned specifically to the transducer characteristics and channel dimensions is applied to the device, and an acoustic standing wave is set up within the microchannel, producing a trapping zone at a pressure node. This method exploits the density, volume, and compressibility differences between sperm cells and free DNA from epithelial cell lysate to create a force strong enough to retain the sperm cells at these nodes, while allowing the free DNA to pass through the device. Laminar flow valving is implemented to direct the two fractions to separate outlets.