New Covid-19 testing method gives results in one second, scientists say

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New Delhi: Scientists have developed a novel sensor system that can detect the novel coronavirus from saliva samples in one second, which is way faster than current Covid-19 diagnostic methods.

Detecting the presence of the coronavirus requires amplifying the number of viral biomarkers, such as the copies of its genetic material. This can be done either using a technique called the polymerase chain reaction (PCR), or amplifying the binding signal for a target biomarker.

The new rapid and sensitive test, described in the Journal of Vacuum Science & Technology B, uses the second method but in a sophisticated way.

The reverse transcription polymerase chain reaction (RT-PCR) test is widely regarded as the “gold standard” for Covid-19 testing. However, some PCR tests may yield results in some hours or few days depending on if the samples are tested on-site or are sent elsewhere for testing.

“The new test could alleviate slow Covid-19 testing turnaround time issues,” said Minghan Xian, an author and a chemical engineering doctoral candidate at the University of Florida.

“Our biosensor strip is similar to commercially available glucose test strips in shape, with a small microfluidic channel at the tip to introduce our test fluid,” said Xian. Within the microfluidic channel, a few electrodes are exposed to the fluid, in this case saliva samples.

One is coated with gold, and Covid-relevant antibodies are attached to the gold surface through a chemical method. During measurement, sensor strips are connected to a circuit board via a connector. A short electrical current gets sent between the gold electrode bonded with Covid antibody and the second electrode. This signal is then returned to the circuit board for analysis.

“Our sensor system, a circuit board, uses a transistor to amplify the electrical signal, which then gets converted into a number on the screen,” said Xian.

“The magnitude of this number depends on the concentration of antigen, the viral protein, present within our test solution,” the researcher said.

While the system’s sensor strips must be discarded after use, the test circuit board is reusable. This can greatly reduce the cost of testing, the researchers said. The technology can not only detect Covid-19 but can also be applied to other diseases, they said.

“By altering the type of antibodies attached to the gold surface, we can repurpose the system to detect other diseases,” said Xian. The results show the potential of this approach for the development of a portable, low-cost, and disposable cartridge sensor system for point-of-care detection of viral diseases, the researchers added.