Caltech Researchers Develop Graphene-Based COVID Test and Sensor Technology

February 13, 2021 by Stephanie Leonida

Caltech researchers develop a multiplexed test with a sensor that can rapidly detect and diagnose COVID-19 infection, the SARS-CoV-2 RapidPlex.

The California Institute of technology (Caltech) researchers have developed a standalone unit that uses a test to combine multiple data to help detect and diagnose individuals suspected of being infected with COVID-19. The device integrates a multiplexed test along with a low-cost sensor which could be used for the at-home diagnosis of a COVID-19 infection. 

The researchers say that only a small volume of saliva or blood needs to be used in order to receive a rapid analysis and result within 10 minutes. Additionally, the design and usability of this technology means that there is no need for medical professionals to be involved to use it. 


The SARS-CoV-2 RapidPlex. Image used courtesy of Caltech 
The SARS-CoV-2 RapidPlex. Image used courtesy of Caltech 

COVID-19 has been able to spread all across the world and generate new strains with even more potency concerning the level of transmissibility. The coronavirus can infect individuals and cause mild to severe symptoms, or in other individuals, cause no symptoms at all to develop. 

These individuals can quite easily pass on the virus to colleagues when going to work, to family members within the home, or when meeting someone outdoors without knowing it. To slow the progress of the pandemic it has been increasingly important to develop tests that can rapidly detect the viral infection in asymptomatic carriers. Current testing methods can take hours or even days to generate a definitive result. They can also involve complicated, costly equipment. 


The Graphene-Based COVID-Detecting Sensor

The new sensor was developed within the lab of Assistant Professor, Wei Gao, in the Andrew and Peggy Cherng Department of Medical Engineering. Previous work by Gao and his research team was centered on the development of wireless sensors that could monitor health conditions such as gout. Stress levels could also be measured with these devices through the detection of specific biological components in blood, sweat, or saliva. Previous models of the sensor, now adapted to detect COVID-19, were impregnated with antibodies for the hormone cortisol. This hormone is associated with stress and uric acid, which can cause gout at high concentrations. 

Gao’s latest sensor, the SARS-CoV-2 RapidPlex, is made up of graphene structures along with antibodies and proteins that help with the detection of coronavirus. An antibody is a large Y-shaped protein that is produced by the immune system to identify and neutralize foreign matter entering the body such as viruses and bacteria. In particular, antibodies recognize a specific molecule of a particular pathogen (such as coronavirus), known as an antigen. The graphene structures of the sensor have very small pores that take up a large surface area. This enables accurate detection of low levels of certain compounds and matter such as the antigens of coronavirus. Data collected with the RapidPlex can be wirelessly transmitted to a mobile user interface. 


Image used courtesy of Caltech 
Image used courtesy of Caltech 


In a news release from October last year, Gao commented: "This is the only telemedicine platform I've seen that can give information about the infection in three types of data with a single sensor.” Gao added: "In as little as a few minutes, we can simultaneously check these levels, so we get a full picture about the infection, including early infection, immunity, and severity."


Potential and Push for At-Home Detection

Although the RapidPlex sensor has been reported to be highly accurate, the results are preliminary. The pilot study involved the testing of a small number of blood and saliva samples in the Gao lab. The next stage is to complete a large-scale test with real-world patients and to test the sensor over a long period, for functionality. After testing patients with COVID-19 in hospitals, Gao plans to study the suitability of the RapidPlex for use at-home. 

"Our ultimate aim really is home use," said Gao. "In the following year, we plan to mail them to high-risk individuals for at-home testing. And in the future, this platform could be modified for other types of infectious disease testing at home,” Gao added.