A smartphone virus scanner with a difference

A virus scanner for a smartphone might not sound too exciting at first, but the device developed by researchers at the University of Tokyo doesn’t search for the latest malware; it scans biological samples for real viruses.

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. Although designed to be highly accurate at counting viruses, these tools are just too cumbersome for many situations — particularly due to certain economic and geographic factors, and especially when rapid diagnosis is required.

With this in mind, Tokyo researcher Yoshihiro Minagawa decided to create and test an alternative miniaturised system that makes use of low-cost components and a smartphone. Described in the journal Lab on a Chip, the system could help to tackle the spread of diseases.

“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.”

The device is about the size of a brick, with a slot on top in which you place a smartphone such that its camera looks through a small lens to the inside of the device. On the screen through a custom-made smartphone app you would see what may at first glance look like a starry night sky, except those stars would in fact be individual viruses.

Images are clearer with microscopes (right), but smartphones (left) continually improve. Image© 2019 Minagawa et al.

Viruses are held in place on a clear surface in tiny cavities lit with an 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 femtolitres (quadrillionths of a litre) — it would take over 10 million of these to hold a single human tear.

“This is now possible because smartphones and their embedded cameras have become sufficiently advanced and more affordable,” Minagawa said.

The virus-containing cavities are 4.5 µm across and 9 µm apart. Image© 2019 Minagawa et al.

“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.

“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 system was tested with viruses but could also detect other biological markers, with Minagawa saying, “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 maximise its usefulness to those on the front line of disease prevention, helping to save lives.”

Top image: The device without a smartphone (left) and with a smartphone attached (right). Image© 2019 Rohan Mehra, Division for Strategic Public Relations.

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