Findings and methodology are presented for a project with the goal of developing automated sperm recognition software for use with a device for automated sample handling and sperm isolation in the analysis of sexual assault evidence samples.
Such automation could significantly reduce the amount of manual labor required in processing sexual assault DNA evidence and facilitate record-keeping. This project builds on previous NIJ-funded work that established the compatibility of optical trapping and fluorescent staining of sperm with STR analysis, and it supported the development of key components of an integrated device for using holographic optical trapping (HOT) for automated isolation of sperm cells from eluted sexual assault evidence swabs. This report on the current project indicates that the hardware challenges encountered proved to be more important than researchers had anticipated. These challenges and how they were addressed to the satisfaction of the researchers are discussed. The researchers were then able to proceed with acquiring good bright-field images of eluted sperm, and they developed image-analysis software techniques for identifying sperm and distinguishing it from other particles that might be found on a sexual assault evidence swab, such as yeast; however, researchers were unable to make further progress in image-analysis work or attempt DNA quantitation through image analysis. This was because the research and development program was terminated prior to the end of the funding period. This was due to business decisions that resulted in a significant reduction in resources and personnel available to support the project. This report presents recommendations for future researchers who may pursue similar work. A priority recommendation is to design and produce a new, integrated hardware system designed for the sperm-isolation application. 26 figures, 5 tables, and 32 references