University of Pennsylvania engineers have developed a rapid, low-cost genetic test for the Zika virus. The $2 testing device, about the size of a soda can, does not require electricity or technical expertise to use. A patient would simply provide a saliva sample. Color-changing dye turns blue when the genetic assay detects the presence of the virus.The engineers demonstrated the design and efficacy of their test in a study published in the journal Analytical Chemistry. It was conducted by Research Assistant Professor Changchun Liu and Professor Haim Bau of the Department of Mechanical Engineering and Applied Mechanics in Penn’s School of Engineering and Applied Science, along with members of the Bau lab, Jinzhao Song and Michael Mauk. They collaborated with Sara Cherry, associate professor of microbiology in Penn’s Perelman School of Medicine, and Brent Hackett, a member of her lab.