French researchers have developed a new COVID-19 test that can deliver results on a smartphone within 10 minutes and doesn't require processing in a lab.

Scientists from the universities of Lille and Marseille and the French National Center for Scientific Research (CNRS) say initial trials of the prototype test, called CorDial-1, on 300 samples showed a 90 percent accuracy rate compared with a Polymerase Chain Reaction (PCR) test, the most reliable commonly-used method of detecting COVID-19.

The prototype test can deliver results three times faster than cheap (and debated) rapid lateral flow antigen tests, and can be used outside the laboratory, according to the team developing it, while PCR testing is expensive to perform, can typically take at least six hours to show results and needs lab conditions.

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It also comes in the form of a nifty device the size of a large USB stick which is plugged into a smartphone to display the results.

"Somebody has to take a nasal swab of you, you will put the sample directly on the electrode, you can put the telephone on the table, you can have a coffee, some ice cream, even a shower and ten minutes later you come back," explained Sabine Szunerits, nano-medicine and biosensor specialist at the University of Lille and one of the CorDial project leaders.

The innovative CorDial-1 test uses completely different technology in the form of an electrochemical test which uses tiny antibody fragments called nanobodies from animals. They are derived from camelids – a group that includes camels, dromedaries, llamas and alpacas – because they are more stable than antibodies from other animals.

For the rapid COVID-19 test, the nanobodies are grafted onto the surface of an electrode to become an electrochemical biosensor. When those nanobodies come into contact with the "spike" protein of the COVID-19 virus, they interact to produce a change in the electrical current across the electrode. 

This change is then measured by the device and displayed in real time on the smartphone screen as a signal on a graph.

"You start up your mobile phone, a signal will appear, and depending on the height of the signal, you can say if you're COVID-19 positive or negative," Szunerits explained. 

The CorDial project is partly funded by the European Union through a grant of $2.8 million, and the scientists behind it hope that soon after the next phase of running a three-month trial on more than 1,000 people, it can then be manufactured and distributed for wider use.

"It could be mass-produced very quickly, and has obvious application in hospitals and airports but also for family doctors and pharmacists," David Devos, a pharmacology professor at the University of Lille and one of the project leaders, told local media.

According to the project website, the researchers say the current prototype using a nasal swab could be very useful in medical settings and could be provided in a matter of weeks. "CorDial makes it possible to respond to the need for rapid diagnosis in emergency care situations (admissions, hospitalizations, invasive procedures and surgical)," they explained.

But the test could also be useful in airports, schools and other social settings to help with safe reopening once it is mass-produced. Scientists are also developing a test that could use saliva samples instead of nasal ones, which would make it much easier and more convenient for self-testing at home.

The researchers say it could also have wider uses beyond the COVID-19 pandemic. "For the moment, we are on COVID-19 because it is an emergency," Rabah Boukherroub of the CNRS in Lille told local media. "But this can be applied to other viruses, bacteria or environmental analyzes. After COVID-19 anything is possible," he added.

Christophe Demaille, lead researcher in molecular electrochemistry at the University of Paris, who is not involved in the project, said tests that rely on electrical signals are highly portable, and the project shows great promise to make testing easier.

"I am confident it will be usable anywhere," he said of the CorDial project.

Video editor: Pedro Duarte