Forensic Science and Technology Commons^™

Optical Tweezers As An Effective Tool For Spermatozoa Isolation From Mixed Forensic Samples, Nicole Auka, Michael Valle, Bobby D. Cox, Peter D. Wilkerson, Tracey Dawson Cruz, Joseph E. Reiner, Sarah J. Seashols-Williams

Forensic Science Publications

A single focus optical tweezer is formed when a laser beam is launched through a high numerical aperture immersion objective. This objective focuses the beam down to a diffraction-limited spot, which creates an optical trap where cells suspended in aqueous solutions can be held fixed. Spermatozoa, an often probative cell type in forensic investigations, can be captured inside this optical trap and dragged one by one across millimeter-length distances in order to create a cluster of cells which can be subsequently drawn up into a capillary for collection. Sperm cells are then ejected onto a sterile cover slip, counted, and …