Smartphone COVID-19 Test Image
Researchers image a sample using a smartphone microscope. (Credit: University of Arizona)

A COVID-19 testing method uses a smartphone microscope to analyze saliva samples and deliver results in about 10 minutes. The researchers aim to combine the speed of existing nasal swab antigen tests with the high accuracy of nasal swab PCR, or polymerase chain reaction, tests.

Traditional methods for detection of norovirus or other pathogens are often expensive, involve a large suite of laboratory equipment or require scientific expertise. The smartphone-based norovirus test consists of a smartphone, a simple microscope and a piece of microfluidic paper — a wax-coated paper that guides the liquid sample to flow through specific channels. It is smaller and cheaper than other tests, with the components costing about $45.

The basis of the technology 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.