Thursday , January 21 2021

How graphene sensors can help collect fast COVID test results

SARS-CoV-2 RapidPlex. Image credit: SARS-CoV-2 RapidPlex: Graphene-based multiplexed telemedicine platform for fast and cheap diagnosis and monitoring of COVID-19, ‘ Matter, [DOI: 10.1016/j.matt.2020.09.027]

Researchers from CalTech have developed a stand-alone cheap COVID-19 test that can provide results in 10 minutes at home, even for people who have no symptoms.

Diagnosis is a major battle in the war against COVID-19, a virus that has affected our way of life and has so far cost nearly 2 million lives. Now a research team from the Calfornia Institute of Technology (CalTech) could deal a big blow in this battle.

The team designed a stand-alone electronic unit – the SARS-CoV-2 RapidPlex – that is highly adapted to COVID’s specific biochemical labels. This could allow on-site testing, identifying the presence of the virus within 10 minutes. This gives it a great advantage over current methods, which can take hours or even days to achieve a result.

The unit even makes a diagnosis for people who show no symptoms at the time of testing. This could make a significant difference in the fight against the virus, which is easily spread by asymptomatic vectors.

What makes the SARS-CoV-2 RapidPlex unit even more impressive is the fact that it consists of a combination of inexpensive sensors, which potentially makes it quite economical to manufacture. In addition, the unit processes the collected data and reports its results on the user’s smartphone, making it adaptable and portable. Crucially, this means that the unit can be operated without the need for a medical professional, which means that users can apply the test in their homes.

One of the reasons the unit is so effective is that it can electrochemically identify three important molecular biomarkers. Namely, the virus itself, the antibody of the immune response created to fight it, and the protein associated with inflation, the detection of which may indicate the severity of the infection.

Consequently, the SARS-CoV-2 RapidPlex unit can detect COVID-19 from extremely low levels of specific components in body fluids such as blood, saliva, and even sweat.

This is the only telemedicine platform I have seen that can provide infection information in three types of data with a single sensor. In just a few minutes, we can check these levels at the same time, so we get a complete picture of the infection, including early infection, immunity, and severity.

Wei Gao, Lead Researcher and Assistant Professor, Department of Medical Engineering, CalTech

Researchers discuss their potential discovery in a paper published in the journal Matter¹.

Graphene sensors catch COVID-19 biomarkers

One of the keys to the efficiency of the SARS-CoV-2 RapidPlex unit is its sensors and the material that coats them. The unit’s sensor array has four graphene electrodes, a silver / silver-chlorine electrode and an anti-electrode graphene, all laser engraved on a polyimide substrate.

Antigens and antibodies are immobilized on laser engraved micropores etched into graphene electrodes. In addition to incorporating these molecules, micropores mean that the sensors have a large surface area, which means that even when working with minuscular samples, the proteins used in SARS-CoV-2 RapidPlex deliver enough material to detect the presence of COVID-19.

The surface of the sensor also benefits from the use of graphene which has a large surface area due to the fact that it consists of a single layer of carbon atoms. Graphene also allows electrons to move through and through it quite smoothly. This high-charge mobility gives the unit high sensitivity and the ability to switch sensor strategies.

Graphene gives another benefit to the devices that use it; the fact that it is both cheap and plentiful. Together with the fact that both phases of laser engraving are involved in the process of creating sensors containing SARS-CoV-2 RapidPlex fast and cost-effective, this means that the unit should be both economical and mass-productive.

The result is a convenient tool for fast, accurate and phase-specific detection of COVID-19 infection.

Moving SARS-CoV-2 RapidPlex from the laboratory

Currently, SARS-CoV-2 RapidPlex is in the phase of laboratory testing of its development. Although they showed impressive results that Gao says indicate high sensitivity, they were produced with small samples. Thus, the unit must now be proven by larger samples.

The CalTech team will now test SARS-CoV-2 RapidPlex with real-world samples collected directly from patients, rather than on laboratory-prepared samples obtained from patients who have already had a positive or negative test.

All of this means moving SARS-CoV-2 RapidPlex from labs to hospitals and monitoring it, starting “at home” testing.

Our ultimate goal is truly home use. Next year, we plan to send them to high-risk individuals for testing at home. And in the future, this platform could be modified for other types of infectious disease testing at home.

Wei Gao, Lead Researcher and Assistant Professor, Department of Medical Engineering, CalTech


¹ Gao. W., Torrente-Rodríguez. RM, Lukas. H., and others, [2020],, SARS-CoV-2 RapidPlex: Graphene-based multiplexed telemedicine platform for fast and cheap diagnosis and monitoring of COVID-19, ‘ Matter, [DOI: 10.1016/j.matt.2020.09.027]

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