Norovirus causes about 20 million cases of food poisoning in the U.S. every year. Diarrhea and vomiting are the most common symptoms. Thanks in part to these symptoms, infected people shed billions of virus particles. And if 10 of those particles somehow make their way into another person, via, let’s say, water or food contamination, that second person can also get sick. Norovirus is most famous for burning its way through cruise ships and other close quarters, but it can also strike municipal water systems, schools, and restaurants. Jeong-Yeol Yoon and his colleagues from the University of Arizona are working on an easy, inexpensive, and extremely sensitive way to detect norovirus using a cell phone and mostly off-the-shelf parts. The system starts with a paper microfluidics chip. Potentially contaminated water is added
to the chip. Then, fluorescent beads that are covalently linked to antibodies against norovirus are added. The two liquids mix. If norovirus is present, virus particles will
bind to multiple antibodies, each attached to its own fluorescent bead. This amplifies the signal. To see that signal, Yoon and his colleagues turned an off-the-shelf cell phone into a fluorescence microscope by adding a light microscope, a light source, and a couple filters. They also wrote software to analyze images of the microfluidics chip, count the number of illuminated pixels, and convert that into a count of norovirus particles. The device could be deployed on cruise ships and other areas where labs are inaccessible; but they could also be used to quickly test, for example, hundreds of water wells onsite rather than taking samples and carting them back to the lab to do more expensive and time-consuming analysis. Yoon is presenting these research findings at the American Chemical Society’s Fall National Meeting and Exposition in San Diego.