New paper-based sensor tests for COVID-19 in five minutes

A group of engineers has developed a fast, ultra-sensitive test using a paper electrochemical sensor to detect COVID-19 in less than five minutes.

There are two of the most common types of COVID-19 tests on the market. The first uses the polymerase chain reaction (PCR) and nucleic acid hybridization strategies to identify viral RNA. FDA-approved diagnostic tests use this method. However, they have a major drawback: the time required to complete the test and the need for specialized personnel, and the mandatory access to equipment and reagents.

The second category of tests focuses on the detection of antibodies. However, it can take anywhere from a few days to several weeks after being exposed to the virus to develop antibodies.

In recent years, researchers have made some progress in developing biosensors used at points of care. To create them, the developers used two-dimensional nanomaterials, for example, graphene. It is needed to detect diseases. The main advantages of graphene-based biosensors are their sensitivity and low production costs and fast results.

The biosensor consists of two components: a platform for measuring electrical parameters and probes that detect viral RNA. The researchers first coated filter paper with a layer of graphene nanoplates to create a conductive film to create a platform. They then placed a gold electrode on top of the graphene as a contact pad for electrical readout. Both gold and graphene are susceptible and highly conductive, making this platform ultra-sensitive: it can detect changes in electrical signals.

The team tested the sensor’s performance by testing several volunteers for COVID-19. The sensor confirmed the presence of viral genetic material in less than five minutes. Also, he was able to determine the RNA viral load in these samples. Viral load is an important quantitative indicator of the development of an infection, which is difficult to measure using existing diagnostic methods.

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