Researchers at the University of Arizona are designing a Covid-19 testing method that relies on a smartphone microscope to analyse saliva samples and deliver results in about 10 minutes.

The research team, led by biomedical engineering professor Jeong-Yeol Yoon, aims to bring a system that has the speed of antigen tests and accuracy of RT-PCR tests.

For this, the researchers are adapting an inexpensive method that they originally created to detect norovirus - the microbe famous for spreading on cruise ships - using a smartphone microscope. They plan to use the method in conjunction with a saline swish-gargle test developed by Michael Worobey, head of the UArizona Department of Ecology and Evolutionary Biology and associate director of the University of Arizona BIO5 Institute.

The team’s latest research using water samples is published today in Nature Protocols. “We’ve outlined it so that other scientists can basically repeat what we did and create a norovirus-detecting device,” said Lane Breshears, a biomedical engineering doctoral student in Yoon’s lab.

He added: “Our goal is that if you want to adapt it for something else, like we’ve adapted it for Covid-19, that you have all the ingredients you need to basically make your own device.”

The researcher explained that the basis of the technology, described in a 2019 paper published in the journal ACS Omega, is relatively simple. Users introduce antibodies with fluorescent beads to a potentially contaminated water sample. If enough particles of the pathogen are present in the sample, several antibodies attach to each pathogen particle.

Under a microscope, the pathogen particles show up as little clumps of fluorescent beads, which the user can then count. The process - adding beads to the sample, soaking a piece of paper in the sample, then taking a smartphone photograph of it under a microscope and counting the beads - takes about 10 to 15 minutes the authors noted.

Moreover, according to the researchers, it is smaller and cheaper than other tests, with the components costing about $45. The researchers plan to partner with testing facilities at the University of Arizona to fine-tune their method as they adapt it for Covid-19 detection.