US scientists develop cheap smartphone-based test kit for Covid

·2-min read
<span>Photograph: Robert Ghement/EPA</span>
Photograph: Robert Ghement/EPA

Doing a test with new technique could cost a 10th of a PCR and has been as reliable in small-scale trial

Scientists have developed a highly sensitive Covid test that relies only on low-tech kit and a smartphone, which could be used as a quicker, cheaper alternative to PCR testing.

The team behind the 25-minute saliva test say it provides a highly reliable platform for testing in the workplace or at home. It requires a basic lab kit that includes a cardboard box, a small hot plate and LED light that can be produced for less than £75. The cost of running a test, including the reagents, is about a 10th of a PCR test and is also cheaper than a lateral flow test. The team’s findings are published in the journal JAMA Network Open.

“As new Covid variants emerge globally, testing and detection remain essential to pandemic control efforts,” said Dr Michael Mahan, of the University of California, Santa Barbara and lead author. “Nearly half the world’s population has a smartphone, and we believe that this holds exciting potential to provide fair and equal access to precision diagnostic medicine.”

Related: Faster than a PCR test: dogs detect Covid in under a second

The test uses a process called Loop-mediated Isothermal Amplification (Lamp) to amplify viral RNA in the saliva and detect specific target genes. The app, which is freely available, uses a smartphone’s camera to measure colour changes indicating a chemical reaction and determines a diagnosis in 25 minutes. When tested in 50 patients with Covid, it matched PCR testing for sensitivity. The same technique was also applied successfully to diagnosing flu infections.

Alexander Edwards, of the University of Reading, said the work demonstrates it is possible to move testing out of the laboratory. “This interesting report is important in showing the accuracy of a relatively simple test for virus in swabs from clinical samples,” he said. “However, many other research groups have already shown that this type of technology and test simplification can work. The challenge remains how to deliver large-scale products based on this type of technology, and to make simple, accessible products that people can make use of.”

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