PICTURE: When connected to the accompanying electronics, the sensor can wirelessly transmit data to the user’s mobile phone via Bluetooth. see more
One feature of the COVID-19 virus that makes it so difficult to retain is that a person who has not yet shown signs of infection can easily spread it to others. The virus carrier could feel perfectly well and go about his daily business – taking the virus with him to work, to the home of a family member, or to public gatherings.
Therefore, a crucial part of the global effort to stop the spread of the pandemic is the development of tests that can quickly identify infections in people who do not yet have symptoms.
Now Caltech researchers have developed a new type of multiplexed test (a test that combines multiple types of data) with a low-cost sensor that can enable a home diagnosis of COVID infection by rapid analysis of small amounts of saliva or blood, without medical intervention, in less than 10 minutes.
The research was conducted in the laboratory of Wei Gao, assistant professor of medical engineering Andrew and Peggy Cherng. Prior to that, Gao and his team developed wireless sensors that can monitor conditions such as gout as well as stress levels, by detecting extremely low levels of specific compounds in blood, saliva or sweat.
Gao sensors are made of graphene, a carbon-shaped sheet metal. The laser-engraved plastic sheet creates a 3D graphene structure with tiny pores. These pores create a large surface area of the sensor, which makes it sensitive enough to detect with great accuracy the compounds that are present only in very small quantities. In this sensor, graphene structures are associated with antibodies, molecules of the immune system that are sensitive to certain proteins, such as those on the surface of the COVID virus, for example.
Previous versions of the sensor were impregnated with antibodies to the hormone cortisol, which is associated with stress, and uric acid, which in high concentrations causes gout. The new version of the sensor, which Gao called the SARS-CoV-2 RapidPlex, contains antibodies and proteins that allow it to detect the presence of the virus itself; antibodies that the body makes to fight the virus; and chemical markers of inflammation indicating the severity of COVID-19 infection.
“This is the only telemedicine platform I’ve seen that can provide infection information in three types of data with a single sensor,” Gao says. “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 weight.”
Established COVID testing technologies typically take hours or even days to achieve results. These technologies also require expensive, complex equipment, while Gao’s system is simple and compact.
So far, the device has only been tested in a laboratory with a small number of blood and saliva samples obtained in medical research from people who are positive or negative for COVID-19. Although preliminary results show that the sensor is very accurate, a larger test must be performed with real patients, not laboratory samples, Gao warns, in order to definitely determine its accuracy.
Now that the pilot study is now complete, Gao plans next time to test how long the sensors last with regular use and start them with hospitalized patients with COVID-19. After in-hospital testing, he would like to study the suitability of the tests for home use. After testing, the device will need to obtain regulatory approval before it can be widely used at home.
“Our ultimate goal is really home use,” he says. “Next year, we plan to send them to high-risk people for testing at home. And in the future, this platform could be modified for other types of testing for infectious diseases at home.”
The paper describing the research, titled “SARS-CoV-2 RapidPlex: A Multiplexed Telemedicine Platform for Fast and Cheap Graphene-Based COVID-19 Diagnosis and Monitoring,” has been published online and will appear in the December issue of Matter magazine. Co-authors are former postdoctoral student in medical engineering Rebeca M. Torrente-Rodríguez, graduate students of medical engineering Heather Lukas, Jiaobing Tu (MS ’20), Jihong Min (MS ’19), Yiran Yang (MS ’18) and Changhao Xu ’20); and Harry B. Rossiter of Harbor-UCLA Medical Center.
Funding for the research was provided by the National Institutes of Health; Tobacco-Related Disease Research Program, California state agency aimed at reducing tobacco use; Merkin Institute for Translational Research; and the Translational Research Institute for Space Health.
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