This VCU professor’s invention speeds up how sexual assault DNA evidence is processed

The device could one day play a key role in reducing the nation’s backlog of untested rape kits and expedite crime solving.
Tracey Dawson Cruz, Ph.D., professor and chair of the Department of Forensic Science, shows the plastic microchip developed by her team that is inserted into the device to prepare a sample for DNA analysis

An automated device being developed in a lab in the Department of Forensic Science at Virginia Commonwealth University can process sexual assault DNA evidence faster and at a much lower cost than existing methods.

The device — invented by Tracey Dawson Cruz, Ph.D., professor and chair of the Department of Forensic Science in the College of Humanities and Sciences, in collaboration with James P. Landers, Ph.D., at the University of Virginia — could one day speed up evidence processing in crime solving and help address the nation’s backlog of untested rape kits, estimated to be in the hundreds of thousands.

“Our goal is [to provide] a tabletop device that is less than a shoebox in size and that will make the front-end steps of forensic DNA examiners’ workflow much faster and hands-free,” Dawson Cruz said. “The idea is that by making the bench work faster, it will free up their time to do data analysis, which is where the bottlenecks are in forensic DNA labs.”

By automating several steps needed to prepare DNA evidence for analysis, the device reduces the overall processing time from 5-6.5 hours down to 90 minutes. It reduces forensic examiners’ hands-on time from 2.5-3.5 hours to just 10 minutes.

The device is also significantly cheaper than traditional methods. Conventional lab equipment costs roughly $12,000, while the team’s third-generation prototype’s hardware cost is around $1,550.

Tracey Dawson Cruz in her lab
Tracey Dawson Cruz, Ph.D., professor and chair of the Department of Forensic Science, has been developing the technology since 2011. (Photo by VCU Innovation Gateway)

The average cost of processing a DNA sample using conventional methods is $6.04. The estimated cost per sample using the new device is $3.38.

“These [plastic microchips] are cheaper than the tubes that we typically work with in a lab,” Dawson Cruz said. “The materials cost is 30 cents a sample.”

To use the device, an analyst cuts a swab containing DNA evidence and places it on a disposable layered plastic microchip about the size of a credit card. The microchip, which has several channels and chambers, is inserted into the device, which then spins the microchip, using centrifugal force for cell separation, DNA extraction and DNA amplification. It will eventually be capable of processing six to eight samples simultaneously.

Dawson Cruz and her lab have been working on the device since 2011. Her lab invented the microchip and its architecture, as well as the chemistry that occurs inside the device. At UVA, Landers, an expert in microfluidics and microanalytics, and his lab led the engineering of the instrument and continue to help with troubleshooting.

“This was a perfect unmet need to which our centrifugal microfluidics expertise could be applied,” said Landers, a professor of chemistry, mechanical engineering and pathology. “The ‘move fluids by spinning’ concept reduces both cost and size.”

prototype of automated device in development at VCU by Tracey Dawson Cruz
The prototype device, currently in its third generation, uses centrifugal force to spin the plastic microchip in a precise way to process a DNA sample for analysis. (Photo by Brian McNeill)

The device’s development has been supported with funding from the U.S. Department of Justice and from VCU Innovation Gateway’s Commercialization Fund, which is dedicated to the advancement of VCU inventions.

VCU Innovation Gateway is marketing the invention to potential industry partners who could license the patented technology and bring it to market, where it one day could be put into use in the nation’s roughly 400 accredited forensic crime labs.

“VCU Innovation Gateway has been working with and supporting Tracey for almost four years, and we are very impressed with the progress she has made in developing and testing the device,” said Magdalena K. Morgan, Ph.D., assistant director of VCU Innovation Gateway and a manager of the technology. “We truly believe that once the microchip reaches the market, it will have a great impact on lives of sexual assault victims.”

The device received early product feedback from North Carolina State University’s Technology Entrepreneurship and Commercialization program. The program assembled a team that included engineers, a biologist, a computer scientist and an M.B.A. student with startup experience. The team conducted market research and analytics and met with legal, financial, technological, regulatory and end-user stakeholders. That team’s work, Dawson Cruz said, has helped support the device’s development and marketing to industry.

“Over the course of two years, they go through the process that a potential investor would go through,” Dawson Cruz said. “They shop the market, they do business analytics on the technology, and over each semester they whittle down [several potential technologies] so that by the end of the two years they’re left with a single technology that they pitch. We were lucky enough with our team to be that one that made it through the entire two-year process.”

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