The current leading method to assess the presence of viruses and other biological markers of disease is effective but large and expensive, according to researchers at the University of Tokyo in Japan. The current system is also prohibitively difficult for use in many situations, especially due to certain economic and geographic factors, they said.

The researchers have created and tested an alternative miniaturized system that makes use of low-cost components and a smartphone. The researchers said they hope the system could aid those who tackle the spread of diseases.

The virus scanner is a portable, low-cost, battery-powered device and is the brainchild of Yoshihiro Minagawa from the University of Tokyo. It was tested with viruses but could also detect other biological markers, the university said.

"I wanted to produce a useful tool for inaccessible or less-affluent communities that can help in the fight against diseases such as influenza," Minagawa said. "Diagnosis is a critical factor of disease prevention. Our device paves the way for better access to essential diagnostic tools."

Current state-of-the-art tools for detecting and counting viruses and other biomarkers, such as fluorescence microscopes, are generally large, expensive, slow and difficult to use, the University of Tokyo said. Although highly accurate at counting viruses, these tools are just too cumbersome for many situations, especially when rapid diagnosis is required.

"Given two equal samples containing influenza, our system detected about 60% of the number of viruses as the fluorescence microscope, but it's much faster at doing so and more than adequate to produce good estimates for accurate diagnoses," Minagawa added. "What's really amazing is that our device is about 100 times more sensitive than a commercial rapid influenza test kit, and it's not just limited to that kind of virus."

The device is about the size of a brick and has a slot on top in which a smartphone can be placed such that its camera looks through a small lens to the inside of the device. On the screen through a custom-made smartphone app, a user would see a "starry" field representing individual viruses, the university explained.

Viruses are held in place on a clear surface in tiny cavities lit with a light-emitting diode (LED). The surface and fluid surrounding it were designed so that only when a cavity has a virus inside does incident light — the light that directly hits the surface — from the LED redirect up to the camera, manifesting in a bright pixel in an otherwise dark void. Each cavity is 48 femtoliters (quadrillionths of a liter); it would take more than 10 million of these cavities to hold a single human tear.

"This is now possible because smartphones and their embedded cameras have become sufficiently advanced and more affordable. I now hope to bring this technology to those who need it the most," Minagawa said. "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."

The device was described in the journal Lab on a Chip.