COVID-19 can be easily spread to others by a person who has yet to show any signs of infection. The carrier of the virus might feel perfectly well and take the virus with them to work, to the home of a family member, or to public gatherings. An at-home test that can rapidly identify infections in people who are not yet symptomatic could dramatically reduce the number of people exposed.


The RapidPlex test combines multiple kinds of data with a low-cost sensor to enable the at-home diagnosis of a COVID infection through rapid analysis of small volumes of saliva or blood — without the involvement of a medical professional — in less than 10 minutes and send the data to the user’s cellphone. The wireless sensors detect extremely low levels of specific compounds in blood, saliva, or sweat. They are made of graphene, a sheet-like form of carbon. A plastic sheet etched with a laser generates a 3D graphene structure with tiny pores. Those pores create a large amount of surface area on the sensor, which makes it sensitive enough to detect, with high accuracy, compounds that are only present in very small amounts. In the sensor, the graphene structures are coupled with antibodies — immune system molecules that are sensitive to specific proteins like those on the surface of a COVID virus — and proteins that allow it to detect the presence of the virus itself, antibodies created by the body to fight the virus, and chemical markers of inflammation that indicate the severity of the COVID-19 infection.

An artist’s rendering showing how the sensor contains areas that each detect a different indicator of a COVID-19 infection. (Credit: Caltech)


California Institute of Technology (Caltech), Pasadena, CA


Established COVID-testing technologies usually take hours or even days to produce results. Those technologies also require expensive, complicated equipment, whereas the new system is simple and compact.


The device has been tested only in the lab with a small number of blood and saliva samples obtained for medical research purposes from individuals who have tested positive or negative for COVID-19. Though preliminary results indicate that the sensor is highly accurate, a larger-scale test with real-world patients must be performed. Following in-hospital testing, the researchers will study the suitability of the tests for in-home use.

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