Known by most of us for giving cruise ships full of people horrible diarrhea, norovirus is highly contagious, so it's best detected early. With that in mind, scientists have developed a smartphone-based system that can do the job instantly, on the spot.
Although it already is possible to detect norovirus in water or food samples, processing those samples typically involves what's known as a polymerase chain reaction – this must be managed by trained personnel in a lab, and it takes several hours. Led by Dr. Jeong-Yeol Yoon, a research team at the University of Arizona set out to develop something much quicker and more mobile.
Their system utilizes a small paper "chip" etched with microfluidic channels, along with an app on a smartphone that's equipped with an inexpensive microscope lens and LED light source. Users start by adding a drop of water to one end of the chip, and a liquid containing tiny, fluorescent polystyrene beads to the other. Each bead is attached to an antibody against norovirus.
Capillary action causes the water and the bead solution to flow into the middle of the chip, where they mix. If any norovirus particles are present, several of the beads will bind to each one. Unlike the particles and the antibodies themselves, the resulting clumps of beads are large enough to be imaged by the smartphone microscope. This allows the app to count them, and thus determine the concentration of norovirus in the water.
"You don't have to be a scientist or an engineer to run the device," says Yoon. "Analysis will be done automatically by the smartphone app, so all you have to worry about is loading a sample of water onto the chip."
Sources: University of Arizona, American Chemical Society via EurekAlert