NCJ Number
252007
Date Published
November 2017
Length
86 pages
Annotation
Findings and methodology are presented for a three-phase project that developed a prototype system for the rapid, effective processing of sexual assault evidence that involves the identification of the DNA of individuals in a mixture sample, thus facilitating the reduction of the backlog of sexual assault kits awaiting testing.
Abstract
Phase I of the project involved a proof-of-principle effort involving a high-risk approach called acoustic differential extraction (ADE). This is a method that exploits acoustic energy to trap and isolate intact sperm cells in the midst of female cell lysate. Phase II consisted of research that focused on instrument/micro fluidic device engineering and piezo-transducer (PZT) physics that addressed forensically relevant samples. This led to Phase III, which involved the development of the SONIC system (Sex Offender Nodal Isolation of Cells), which is a microfluidic system that couples the basic chemistry in current differential extraction (DE) with the direct isolation of sperm cells with acoustic trapping. The SONIC system is composed of a microfluidic chip that is used for isolation of the male fraction from a sample, along with the hardware that facilitates the microfluidic under the control of a customized software. The prototype uses a laptop graphical user interface in which the user can input the necessary information for executing acoustic trapping. With this system, researchers have achieved the isolation of adequate male fraction from mock samples in which the female to male DNA ratio is as high as 100:1. The system is ready for placement in forensic labs for testing. Extensive figures and 60 references