title: Separation of sperm and epithelial cells based on the hydrodynamic effect for forensic analysis.
abstract: In sexual assault cases, forensic samples are a mixture of sperm from the perpetrator and epithelial cells from the victim. To obtain an independent short tandem repeat (STR) profile of the perpetrator, sperm cells must be separated from the mixture of cells. However, the current method used in crime laboratories, namely, differential extraction, is a time-consuming and labor-intensive process. To achieve a rapid and automated sample pretreatment process, we fabricated a microdevice for hydrodynamic and size-based separation of sperm and epithelial cells. When cells in suspension were introduced into the device's microfluidic channels, they were forced to flow along different streamlines and into different outlets due to their different diameters. With the proposed microdevice, sperm can be separated within a short period of time (0.5 h for a 50-μl mock sample). The STR profiles of the products in the sperm outlet reservoir demonstrated that a highly purified male DNA fraction could be obtained (94.0% male fraction). This microdevice is of low-cost and can be easily integrated with other subsequent analysis units, providing great potential in the process of analyzing sexual assault evidence as well as in other areas requiring cell sorting.
authors.forename: Weiran
authors.initials: W
authors.lastname: Liu
authors.forename: Weixing
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Biomedical Engineering, Tsinghua University School of Medicine , Beijing 100084, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Liu
authors.affiliation: Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science , Beijing 100038, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Ou
authors.forename: Haoran
authors.initials: H
authors.lastname: Liu
authors.forename: Lan
authors.initials: L
authors.lastname: Xie
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science , Beijing 100038, China.
authors.forename: Caixia
authors.initials: C
authors.lastname: Li
authors.affiliation: Fujian Provincial Key Laboratory of Forensic Science and Technology , Forensic Science Division, Department of Fujian Provincial Public Security, Fuzhou 350003, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Cheng