In order to see how many viruses are present in a patient's biological fluid sample, bulky and costly devices such as fluorescence microscopes are typically used – not a good solution for developing nations or remote locations. That's why scientists have developed an inexpensive smartphone-connected gadget that does the job.

The battery-powered tool was designed by a team at the University of Tokyo, led by Yoshihiro Minagawa.

It's about the size and shape of a brick, and has a receptacle on top which a third-party smartphone is slotted into. Additionally, tiny droplets of a patient's biological fluids are placed in an array of micro-cavities within the device.

Any viruses that are present get stained with a dye that's added to the sample. When an LED inside the device subsequently illuminates each cavity, that dye fluoresces, causing the viruses to appear as bright spots against a dark background. The phone's camera lens lines up with a magnifying lens built into the device, allowing users to see (and count) those lit-up viruses via an app on the screen.

When tested on biological fluids containing the influenza virus, the device detected about 60 percent as many individual viruses as a fluorescence microscope. While that's not perfect, Minagawa claims that it's certainly sufficient to determine if a patient has the flu, plus it delivers results much more quickly than a microscope would. Additionally, his team's gadget is reportedly 100 times more sensitive than a commercially-available rapid influenza test kit, plus it can detect other types of viruses.

"This is now possible because smartphones and their embedded cameras have become sufficiently advanced and more affordable," he says. "I now hope to bring this technology to those who need it the most. We also wish to add other biomarkers such as nucleic acids — like DNA — to the options of things the device can detect. This way we can maximize its usefulness to those on the front line of disease prevention, helping to save lives."

A paper on the technology was recently published in the journal Lab on a Chip.

Similar devices, which also utilize smartphones to detect disease biomarkers, have been developed by scientists at the University of South Florida, Columbia University and Sandia National Laboratories, among other places.

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